diff --git a/.gitignore b/.gitignore
index ca7e6d6..3919206 100644
--- a/.gitignore
+++ b/.gitignore
@@ -435,12 +435,16 @@ FodyWeavers.xsd
 *.msm
 *.msp
 
+# Local change logs, egg-infos from package installation and local notebooks for development and interactive work
 times.md
 docs/traffic_light_examples
 misc/mysql-workbench-community_**
 misc/berths_and_terminals.csv
+
 src/notebooks_metz
 src/server/BreCal.egg-info
 src/lib_brecal_utils/**.egg-info/**
+**.egg-info
+**/.~lock*
 
-
+Ampelfunktion.md
\ No newline at end of file
diff --git a/docs/BremenCalling_Datenmodell.xlsx b/docs/BremenCalling_Datenmodell.xlsx
index 67151a3..7f17806 100644
Binary files a/docs/BremenCalling_Datenmodell.xlsx and b/docs/BremenCalling_Datenmodell.xlsx differ
diff --git a/environment.yml b/environment.yml
new file mode 100644
index 0000000..6f4c81a
--- /dev/null
+++ b/environment.yml
@@ -0,0 +1,51 @@
+name: brecal
+
+channels:
+  - conda-forge
+  - carta
+  - anaconda
+  - defaults
+
+dependencies:
+  - pip
+  - colorama>=0.4.6=pyhd8ed1ab_0
+  - coverage>=7.3.0=py311h459d7ec_0
+  - ipykernel>=6.25.1=pyh71e2992_0
+  - ipython>=8.14.0=pyh41d4057_0
+  - jupyterlab>=4.0.5=pyhd8ed1ab_0
+  - mamba>=1.4.9=py311h3072747_0
+  - conda-forge::matplotlib-base>=3.7.2=py311h54ef318_0
+  - conda-forge::matplotlib>=3.7.2=py311h38be061_0
+  - matplotlib-inline>=0.1.6=pyhd8ed1ab_0
+  - conda-forge::pytest>=7.4.0=pyhd8ed1ab_0
+  - conda-forge::pytest-cov>=4.1.0=pyhd8ed1ab_0
+  - python>=3.11.4=hab00c5b_0_cpython
+  - pytz>=2023.3=pyhd8ed1ab_0
+  - setuptools>=68.0.0=pyhd8ed1ab_0
+  - tqdm>=4.66.1=pyhd8ed1ab_0
+  - typing_extensions>=4.7.1=pyha770c72_0
+  - typing_utils>=0.1.0=pyhd8ed1ab_0
+  - conda-forge::pandas>=2.1.0=py311h320fe9a_0
+  - conda-forge/noarch::flask>=2.3.3=pyhd8ed1ab_0
+  - conda-forge::mysql-connector-python>=8.0.31=py311h0cf059c_2
+  - conda-forge::marshmallow>=3.20.1=pyhd8ed1ab_0
+  - conda-forge::marshmallow-dataclass>=8.5.14=pyhd8ed1ab_0
+  - conda-forge::webargs>=8.3.0=pyhd8ed1ab_0
+  - conda-forge::bcrypt>=4.0.1=py311h46250e7_0
+  
+  - conda-forge::cached-property>=1.5.2=hd8ed1ab_1
+  - conda-forge::cached_property>=1.5.2=pyha770c72_1
+  - conda-forge::dsnparse>=0.2.1=pyhd8ed1ab_0
+  
+  - conda-forge::schedule>=1.2.0=pyhd8ed1ab_0
+  
+  - pip:
+  # pip packages and wheels
+    - pyjwt==2.7.0
+    - flask-jwt-extended
+    - pydapper[mysql-connector-python]
+    - coro-context-manager
+    - -e /home/scope/brecal/src/lib_brecal_utils/.
+    - -e /home/scope/brecal/src/server/.
+
+prefix: /home/scope/anaconda3/envs/brecal
diff --git a/src/BreCalClient/Resources/arrow_down_red.png b/src/BreCalClient/Resources/arrow_down_red.png
index 7132feb..14046cc 100644
Binary files a/src/BreCalClient/Resources/arrow_down_red.png and b/src/BreCalClient/Resources/arrow_down_red.png differ
diff --git a/src/BreCalClient/ShipcallExtraControl.xaml b/src/BreCalClient/ShipcallExtraControl.xaml
new file mode 100644
index 0000000..c81f640
--- /dev/null
+++ b/src/BreCalClient/ShipcallExtraControl.xaml
@@ -0,0 +1,14 @@
+<UserControl x:Class="BreCalClient.ShipcallExtraControl"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
+             xmlns:local="clr-namespace:BreCalClient"
+             mc:Ignorable="d" 
+             d:DesignHeight="100" d:DesignWidth="800">
+    <Grid>
+        <Button x:Name="buttonCloseDropDown" Click="buttonCloseDropDown_Click" Grid.Column="2" Background="Transparent" ToolTip="Close extra info" Margin="1" BorderThickness="0" HorizontalAlignment="Left">
+            <Image Source="./Resources/arrow_up_red.png" />
+        </Button>
+    </Grid>
+</UserControl>
diff --git a/src/BreCalClient/ShipcallExtraControl.xaml.cs b/src/BreCalClient/ShipcallExtraControl.xaml.cs
new file mode 100644
index 0000000..8f76d6f
--- /dev/null
+++ b/src/BreCalClient/ShipcallExtraControl.xaml.cs
@@ -0,0 +1,55 @@
+// Copyright (c) 2023 schick Informatik
+// Description: Extra shipcall info shown in drop down
+// 
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Navigation;
+using System.Windows.Shapes;
+
+namespace BreCalClient
+{
+    /// <summary>
+    /// Interaction logic for ShipcallExtraControl.xaml
+    /// </summary>
+    public partial class ShipcallExtraControl : UserControl
+    {
+        public ShipcallExtraControl()
+        {
+            InitializeComponent();
+        }
+
+        #region events
+
+        public event Action<ShipcallExtraControl>? CloseExtraRequested;
+
+        #endregion
+
+        #region Properties
+
+        /// <summary>
+        /// this is our datasource
+        /// </summary>
+        public ShipcallControlModel? ShipcallControlModel { get; set; }
+
+        #endregion
+
+        private void buttonCloseDropDown_Click(object sender, RoutedEventArgs e)
+        {
+            if (this.CloseExtraRequested != null)
+            {
+                this.CloseExtraRequested(this);
+            }
+        }
+    }
+}
diff --git a/src/brecal.mysql/DBManager.cs b/src/brecal.mysql/DBManager.cs
index d5c5571..4c9c593 100644
--- a/src/brecal.mysql/DBManager.cs
+++ b/src/brecal.mysql/DBManager.cs
@@ -55,4 +55,4 @@ namespace brecal.mysql
         }
 
     }
-}
\ No newline at end of file
+}
diff --git a/src/lib_brecal_utils/brecal_utils/__init__.py b/src/lib_brecal_utils/brecal_utils/__init__.py
new file mode 100644
index 0000000..b96d315
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/__init__.py
@@ -0,0 +1,20 @@
+from ._version import __version__
+from brecal_utils.file_handling import get_project_root, ensure_path
+from brecal_utils.test_handling import execute_test_with_pytest, execute_coverage_test
+from brecal_utils.time_handling import difference_to_then
+
+from brecal_utils.validators.time_logic import TimeLogic
+from brecal_utils.validators.validation_rules import ValidationRules
+from brecal_utils.validators.schema_validation import validation_state_and_validation_name
+
+__all__ = [
+	"get_project_root", 
+	"ensure_path", 
+	"execute_test_with_pytest",
+	"execute_coverage_test",
+    "difference_to_then",
+    "TimeLogic",
+    "ValidationRules",
+    "validation_state_and_validation_name",
+]
+
diff --git a/src/lib_brecal_utils/brecal_utils/_version.py b/src/lib_brecal_utils/brecal_utils/_version.py
new file mode 100644
index 0000000..15cf400
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/_version.py
@@ -0,0 +1 @@
+__version__="0.0.1"
\ No newline at end of file
diff --git a/src/lib_brecal_utils/brecal_utils/database/__init__.py b/src/lib_brecal_utils/brecal_utils/database/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/brecal_utils/database/enums.py b/src/lib_brecal_utils/brecal_utils/database/enums.py
new file mode 100644
index 0000000..e038643
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/database/enums.py
@@ -0,0 +1,38 @@
+from enum import Enum
+
+class ParticipantType(Enum):
+    """determines the type of a participant"""
+    NONE = 0
+    BSMD = 1
+    TERMINAL = 2
+    PILOT = 4
+    AGENCY = 8
+    MOORING = 16
+    PORT_ADMINISTRATION = 32
+    TUG = 64
+
+class ShipcallType(Enum):
+    """determines the type of a shipcall, as this changes the applicable validation rules"""
+    INCOMING = 1
+    OUTGOING = 2
+    SHIFTING = 3
+
+class ParticipantwiseTimeDelta():
+    """stores the time delta for every participant, which triggers the validation rules in the rule set '0001'"""
+    AGENCY = 1200.0 # 20 h * 60 min/h = 1200 min
+    MOORING = 960.0 # 16 h * 60 min/h = 960 min
+    PILOT = 960.0 # 16 h * 60 min/h = 960 min
+    PORT_ADMINISTRATION = 960.0 # 16 h * 60 min/h = 960 min
+    TUG = 960.0 # 16 h * 60 min/h = 960 min
+    TERMINAL = 960.0 # 16 h * 60 min/h = 960 min
+
+class StatusFlags(Enum):
+    """
+    these enumerators ensure that each traffic light validation rule state corresponds to a value, which will be used in the ValidationRules object to identify
+    the necessity of notifications.
+    """
+    NONE = 0
+    GREEN = 1
+    YELLOW = 2
+    RED = 3
+
diff --git a/src/lib_brecal_utils/brecal_utils/database/sql_handler.py b/src/lib_brecal_utils/brecal_utils/database/sql_handler.py
new file mode 100644
index 0000000..d50bbbd
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/database/sql_handler.py
@@ -0,0 +1,200 @@
+import numpy as np
+import pandas as pd
+import datetime
+from BreCal.schemas.model import Shipcall, Ship, Participant, Berth, User, Times
+from brecal_utils.database.enums import ParticipantType
+
+class SQLHandler():
+    """
+    An object that reads SQL queries from the sql_connection and stores it in pandas DataFrames. The object can read all available tables
+    at once into memory, when providing 'read_all=True'.
+
+    # #TODO_initialization: shipcall_tug_map, user_role_map & role_securable_map might be mapped to the respective dataframes
+    """
+    def __init__(self, sql_connection, read_all=False):
+        self.sql_connection = sql_connection
+        self.all_schemas = self.get_all_schemas_from_mysql()
+        self.build_str_to_model_dict()
+
+        if read_all:
+            self.read_all(self.all_schemas)
+
+    def get_all_schemas_from_mysql(self):
+        with self.sql_connection.cursor(buffered=True) as cursor:
+            cursor.execute("SHOW TABLES")
+            schema = cursor.fetchall()
+        all_schemas = [schem[0] for schem in schema]
+        return all_schemas
+    
+    def build_str_to_model_dict(self):
+        """
+        creates a simple dictionary, which maps a string to a data object
+        e.g.,
+            'ship'->BreCal.schemas.model.Ship object
+        """
+        self.str_to_model_dict = {
+            "shipcall":Shipcall, "ship":Ship, "participant":Participant, "berth":Berth, "user":User, "times":Times
+        }
+        return
+
+    def read_mysql_table_to_df(self, table_name:str):
+        """determine a {table_name}, which will be read from a mysql server. returns a pandas DataFrame with the respective data"""
+        df = pd.read_sql(sql=f"SELECT * FROM {table_name}", con=self.sql_connection)
+        return df
+
+    def mysql_to_df(self, query):
+        """provide an arbitrary sql query that should be read from a mysql server {sql_connection}. returns a pandas DataFrame with the obtained data"""
+        df = pd.read_sql(query, self.sql_connection).convert_dtypes()
+        df = df.set_index('id', inplace=False) # avoid inplace updates, so the raw sql remains unchanged
+        return df
+    
+    def read_all(self, all_schemas):
+        # create a dictionary, which maps every mysql schema to pandas DataFrames
+        self.df_dict = self.build_full_mysql_df_dict(all_schemas)
+
+        # update the 'participants' column in 'shipcall'
+        self.initialize_shipcall_participant_list()
+        return
+
+    def build_full_mysql_df_dict(self, all_schemas):
+        """given a list of strings {all_schemas}, every schema will be read as individual pandas DataFrames to a dictionary with the respective keys. returns: dictionary {schema_name:pd.DataFrame}"""
+        mysql_df_dict = {}
+        for schem in all_schemas:
+            query = f"SELECT * FROM {schem}"
+            mysql_df_dict[schem] = self.mysql_to_df(query)
+        return mysql_df_dict
+    
+    def initialize_shipcall_participant_list(self):
+        """
+        iteratively applies the .get_participants method to each shipcall.
+        the function updates the 'participants' column.
+        """
+        # 1.) get all shipcalls
+        df = self.df_dict.get('shipcall')
+
+        # 2.) iterate over each individual shipcall, obtain the id (pandas calls it 'name')
+        # and apply the 'get_participants' method, which returns a list
+        # if the shipcall_id exists, the list contains ids
+        # otherwise, return a blank list
+        df['participants'] = df.apply(
+            lambda x: self.get_participants(x.name), 
+            axis=1)
+        return
+    
+    def standardize_model_str(self, model_str:str)->str:
+        """check if the 'model_str' is valid and apply lowercasing to the string"""
+        model_str = model_str.lower()
+        assert model_str in list(self.df_dict.keys()), f"cannot find the requested 'model_str' in mysql: {model_str}"
+        return model_str
+        
+    def get_data(self, id:int, model_str:str):
+        """
+        obtains {id} from the respective mysql database and builds a data model from that.
+        the id should match the 'id'-column in the mysql schema.
+        returns: data model, such as Ship, Shipcall, etc.
+
+        e.g.,
+            data = self.get_data(0,"shipcall")
+            returns a Shipcall object
+        """
+        model_str = self.standardize_model_str(model_str)
+        
+        df = self.df_dict.get(model_str)
+        data = self.df_loc_to_data_model(df, id, model_str)
+        return data
+        
+    def get_all(self, model_str:str)->list:
+        """
+        given a model string (e.g., 'shipcall'), return a list of all
+        data models of that type from the sql
+        """
+        model_str = self.standardize_model_str(model_str)
+        all_ids = self.df_dict.get(model_str).index
+
+        all_data = [
+            self.get_data(_aid, model_str)
+            for _aid in all_ids
+        ]
+        return all_data
+    
+    def df_loc_to_data_model(self, df, id, model_str, loc_type:str="loc"):
+        assert len(df)>0, f"empty dataframe"
+        
+        # get a pandas series from the dataframe
+        series = df.loc[id] if loc_type=="loc" else df.iloc[id]
+
+        # get the respective data model object
+        data_model = self.str_to_model_dict.get(model_str,None)
+        assert data_model is not None, f"could not find the requested model_str: {model_str}"
+
+        # build 'data' and fill the data model object
+        data = {**{'id':id}, **series.to_dict()} # 'id' must be added manually, as .to_dict does not contain the index, which was set with .set_index
+        data = data_model(**data)
+        return data
+    
+    def get_times_for_participant_type(self, df_times, participant_type:int):
+        filtered_series = df_times.loc[df_times["participant_type"]==participant_type]
+        assert len(filtered_series)<=1, f"found multiple results"
+        times = self.df_loc_to_data_model(filtered_series, id=0, model_str='times', loc_type="iloc") # use iloc! to retrieve the first result
+        return times
+    
+    def dataframe_to_data_model_list(self, df, model_str)->list:
+        model_str = self.standardize_model_str(model_str)
+
+        all_ids = df.index
+        all_data = [
+            self.df_loc_to_data_model(df, _aid, model_str)
+            for _aid in all_ids
+        ]
+        return all_data
+
+    def get_participants(self, shipcall_id:id)->list:
+        """
+        given a {shipcall_id}, obtain the respective list of participants.
+        when there are no participants, return a blank list
+
+        returns: participant_id_list, where every element is an int
+        """
+        df = self.df_dict.get("shipcall_participant_map")
+        df = df.set_index('shipcall_id', inplace=False)
+        
+        # the 'if' call is needed to ensure, that no Exception is raised, when the shipcall_id is not present in the df
+        participant_id_list = df.loc[shipcall_id, "participant_id"].to_list() if shipcall_id in list(df.index) else []
+        return participant_id_list
+    
+    def get_times_of_shipcall(self, shipcall)->pd.DataFrame:
+        df_times = self.df_dict.get('times') # -> pd.DataFrame
+        df_times = df_times.loc[df_times["shipcall_id"]==shipcall.id]
+        return df_times
+    
+    def get_times_for_agency(self, non_null_column=None)->pd.DataFrame:
+        """
+        options:
+            non_null_column: 
+                None or str. If provided, the 'non_null_column'-column of the dataframe will be filtered,
+                so only entries with provided values are returned (filters all NaN and NaT entries)
+        """
+        # get all times
+        df_times = self.df_dict.get('times') # -> pd.DataFrame
+
+        # filter out all NaN and NaT entries
+        if non_null_column is not None:
+            df_times = df_times.loc[~df_times[non_null_column].isnull()] # NOT null filter
+
+        # filter by the agency participant_type
+        times_agency = df_times.loc[df_times["participant_type"]==ParticipantType.AGENCY.value]
+        return times_agency
+    
+    def filter_df_by_key_value(self, df, key, value)->pd.DataFrame:
+        return df.loc[df[key]==value]
+    
+    def get_unique_ship_counts(self, all_df_times:pd.DataFrame, query:str, rounding:str="min", maximum_threshold=3):
+        """given a dataframe of all agency times, get all unique ship counts, their values (datetime) and the string tags. returns a tuple (values,unique,counts)"""
+        # get values and optional: rounding
+        values = all_df_times.loc[:, query]
+        if rounding is not None:
+            values = values.dt.round(rounding) # e.g., 'min'
+
+        unique, counts = np.unique(values, return_counts=True)
+        violation_state = np.any(np.greater(counts, maximum_threshold))
+        return (values, unique, counts)
diff --git a/src/lib_brecal_utils/brecal_utils/file_handling.py b/src/lib_brecal_utils/brecal_utils/file_handling.py
new file mode 100644
index 0000000..0b3c171
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/file_handling.py
@@ -0,0 +1,46 @@
+
+
+import os
+
+def get_project_root(root_base_name:str, root_dir:None=None):
+    """
+    given a {root_base_name}, this function searches the parent folders of {root_dir} until
+    the basename matches.
+
+    Example:
+        root_base_name = "brecal"
+        root_dir = "/home/arbitrary_user/brecal/_template/tests"
+
+        returns: "/home/arbitrary_user/brecal"
+
+    arguments:
+        root_base_name:str, base directory name that should be searched for
+        root_dir: defaults to 'None', whereas then the current working directory is selected. Can be an arbitrary path.
+
+    returns: root_dir
+    """
+    if root_dir is None:
+        root_dir = os.getcwd()
+
+    assert root_base_name in root_dir, f"the desired base name MUST be present within the root directory.\nRoot Directory: {root_dir}\nDesired Root Base Name: {root_base_name}"
+    assert root_dir.count(root_base_name)==1, f"found multiple matches for root_base_name" # do not change, as a pytest requires precise wording
+
+
+    while not os.path.basename(root_dir)==root_base_name:
+        root_dir = os.path.dirname(root_dir)
+
+    return root_dir
+
+def ensure_path(path, print_info=0):
+    """
+    Function ensures that a certain directory exists. If it does not exist, it will be created.
+    It further checks if the parent-directory of the file exists and also ensures that.
+    
+    options:
+    print_info: print additional information (debugging)
+    """
+    if not os.path.exists(path):
+        os.makedirs(path)
+        if print_info == 1:
+            print(f"Created directory and subdirectories: {path}")
+    return
diff --git a/src/lib_brecal_utils/brecal_utils/request_status_code.py b/src/lib_brecal_utils/brecal_utils/request_status_code.py
new file mode 100644
index 0000000..c3d72ea
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/request_status_code.py
@@ -0,0 +1,131 @@
+import json
+from abc import ABC, abstractmethod
+from BreCal.schemas.model import obj_dict
+
+
+"""implementation of default objects for http request codes. this enforces standardized outputs in the (response, code, headers)-style"""
+
+def get_request_code(code_id):
+    """convenience function, which returns the desired request code object"""
+    request_code_dict = {
+        200:RequestCode_HTTP_200_OK,
+        201:RequestCode_HTTP_201_CREATED,
+        400:RequestCode_HTTP_400_BAD_REQUEST,
+        403:RequestCode_HTTP_403_FORBIDDEN,
+        404:RequestCode_HTTP_404_NOT_FOUND,
+        500:RequestCode_HTTP_500_INTERNAL_SERVER_ERROR
+    }
+
+    assert code_id in list(request_code_dict.keys()), f"unsupported request code: {code_id}. \nAvailable codes: {request_code_dict}"
+    return request_code_dict.get(code_id)()
+
+class RequestStatusCode(ABC):
+    def __init__(self):
+        return
+    
+    @abstractmethod
+    def __call__(self, data):
+        raise NotImplementedError("any default status code object must be callable")
+    
+    @abstractmethod
+    def status_code(self):
+        raise NotImplementedError("any default status code object should return an integer")
+    
+    @abstractmethod
+    def response(self, data):
+        raise NotImplementedError("the response method should return a binary json object. typically, json.dumps is used")
+
+
+    def headers(self):
+        return {'Content-Type': 'application/json; charset=utf-8'}
+    
+
+class RequestCode_HTTP_200_OK(RequestStatusCode):
+    def __init__(self) -> None:
+        super().__init__()
+
+    def __call__(self, data):
+        return (self.response(data), self.status_code(), self.headers())
+    
+    def status_code(self):
+        return 200
+    
+    def response(self, data):
+        return json.dumps(data, default=obj_dict)
+    
+
+class RequestCode_HTTP_201_CREATED(RequestStatusCode):
+    def __init__(self) -> None:
+        super().__init__()
+
+    def __call__(self, data):
+        return (self.response(data), self.status_code(), self.headers())
+    
+    def status_code(self):
+        return 201
+    
+    def response(self, new_id):
+        return json.dumps({"id":new_id})
+
+
+class RequestCode_HTTP_400_BAD_REQUEST(RequestStatusCode):
+    def __init__(self) -> None:
+        super().__init__()
+
+    def __call__(self, data):
+        return (self.response(data), self.status_code(), self.headers())
+    
+    def status_code(self):
+        return 400
+    
+    def response(self, data):
+        return json.dumps(data)
+
+
+class RequestCode_HTTP_403_FORBIDDEN(RequestStatusCode):
+    def __init__(self) -> None:
+        super().__init__()
+
+    def __call__(self, data):
+        return (self.response(data), self.status_code(), self.headers())
+    
+    def status_code(self):
+        return 403
+    
+    def response(self, message="invalid credentials"):
+        result = {}
+        result["message"] = message
+        return json.dumps(result)
+    
+
+class RequestCode_HTTP_404_NOT_FOUND(RequestStatusCode):
+    def __init__(self) -> None:
+        super().__init__()
+
+    def __call__(self, data):
+        return (self.response(data), self.status_code(), self.headers())
+    
+    def status_code(self):
+        return 404
+    
+    def response(self, message="no such record"):
+        result = {}
+        result["message"] = message
+        return json.dumps(result)
+
+
+class RequestCode_HTTP_500_INTERNAL_SERVER_ERROR(RequestStatusCode):
+    def __init__(self) -> None:
+        super().__init__()
+
+    def __call__(self, data):
+        return (self.response(data), self.status_code(), self.headers())
+    
+    def status_code(self):
+        return 500
+    
+    def response(self, message="credential lookup mismatch"):
+        result = {}
+        result["message"] = message
+        return json.dumps(result)
+    
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/__init__.py b/src/lib_brecal_utils/brecal_utils/stubs/__init__.py
new file mode 100644
index 0000000..0516049
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/stubs/__init__.py
@@ -0,0 +1,5 @@
+
+def generate_uuid1_int():
+    """# TODO: clarify, what kind of integer ID is used in mysql"""
+    from uuid import uuid1
+    return uuid1().int>>64
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/berth.py b/src/lib_brecal_utils/brecal_utils/stubs/berth.py
new file mode 100644
index 0000000..a335c18
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/stubs/berth.py
@@ -0,0 +1,27 @@
+import datetime
+from brecal_utils.stubs import generate_uuid1_int
+from BreCal.schemas.model import Berth
+
+def get_berth_simple():
+    berth_id = generate_uuid1_int() # uid?
+
+    # Note: #TODO: name, participant_id & lock state are arbitrary
+    name = "Avangard Dalben"
+    participant_id = 1 # e.g., Avangard
+    lock = False
+
+    created = datetime.datetime.now()
+    modified = created+datetime.timedelta(seconds=10)
+    deleted = modified+datetime.timedelta(seconds=3)
+
+    berth = Berth(
+        berth_id, 
+        name, 
+        participant_id, 
+        lock, 
+        created, 
+        modified, 
+        deleted, 
+    )
+    return berth
+
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/notification.py b/src/lib_brecal_utils/brecal_utils/stubs/notification.py
new file mode 100644
index 0000000..765eea4
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/stubs/notification.py
@@ -0,0 +1,49 @@
+import datetime
+from brecal_utils.stubs import generate_uuid1_int
+from BreCal.schemas.model import Notification
+
+
+def get_notification_simple():
+    """creates a default notification, where 'created' is now, and modified is now+10 seconds"""
+    notification_id = generate_uuid1_int() # uid?
+    times_id = generate_uuid1_int() # uid?
+    acknowledged = False
+    level = 10
+    type = 0
+    message = "hello world"
+    created = datetime.datetime.now()
+    modified = created+datetime.timedelta(seconds=10)
+
+    notification = Notification(
+        notification_id,
+        times_id,
+        acknowledged,
+        level,
+        type,
+        message,
+        created, 
+        modified
+    )
+    return notification
+
+def get_notification_in_the_past(created_delta_seconds, modified_delta_seconds, acknowledged=False):
+    """
+    creates a notification of the past, where the 
+        'created' date is {created_delta_seconds} seconds ago
+        'modified' date is {modified_delta_seconds} seconds ago
+
+    for example, if datetime.datetime.now() returns 
+        now = datetime.datetime(2023, 9, 15, 7, 25, 50, 733644)), then calling this function
+        as get_notification_modified_in_the_past(2*60, 1*60) provides
+            'created':datetime.datetime(2023, 9, 15, 7, 23, 50, 733644) (two minutes ago)
+            'modified':datetime.datetime(2023, 9, 15, 7, 24, 50, 733644) (one minute ago)
+
+    optionally, one can also overwrite the 'acknowledged' attribute
+    returns notification
+    """
+    notification = get_notification_simple()
+    notification.created = datetime.datetime.now()-datetime.timedelta(seconds=created_delta_seconds)
+    notification.modified = datetime.datetime.now()-datetime.timedelta(seconds=modified_delta_seconds)
+    notification.acknowledged = acknowledged
+    return notification
+
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/participant.py b/src/lib_brecal_utils/brecal_utils/stubs/participant.py
new file mode 100644
index 0000000..697a011
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/stubs/participant.py
@@ -0,0 +1,32 @@
+import datetime
+from brecal_utils.stubs import generate_uuid1_int
+from BreCal.schemas.model import Participant
+
+def get_participant_simple():
+    participant_id = generate_uuid1_int()
+
+    # #TODO: role_type and flags are arbitrary
+    name = "Max Mustermann"
+    street = "Musterstrasse 1"
+    postal_code = "12345"
+    city = "Bremen"
+    role_type = 1 # integer
+    flags = 0 # integer. unclear
+
+    created = datetime.datetime.now()
+    modified = created+datetime.timedelta(seconds=10)
+    deleted = modified+datetime.timedelta(seconds=3)
+
+    participant = Participant(
+        participant_id, 
+        name,
+        street,
+        postal_code,
+        city,
+        role_type,
+        flags,
+        created,
+        modified,
+        deleted
+    )
+    return participant
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/roles.py b/src/lib_brecal_utils/brecal_utils/stubs/roles.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/ship.py b/src/lib_brecal_utils/brecal_utils/stubs/ship.py
new file mode 100644
index 0000000..61468c3
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/stubs/ship.py
@@ -0,0 +1,38 @@
+import datetime
+from brecal_utils.stubs import generate_uuid1_int
+from BreCal.schemas.model import Ship
+
+def get_ship_simple():
+    ship_id = generate_uuid1_int()
+    name = "african halcyon".upper() # 'Schiffe_sample_format.xlsx' uses .upper() for every ship
+    imo = 9343613 # assert str(len(imo))==7
+    callsign = 1234567 # up to 7 characters. assert str(len(callsign))<=7
+    participant_id = generate_uuid1_int()
+    length = 177.13 # assert 0>length<=500
+    width = 28.4 # assert 0>width<=500
+    is_tug = False
+    bollard_pull = None # only if is_tug
+    participant_id = None # only if is_tug
+    eni = "01234567" # Alternative to IMO. Dynamic assertion? assert len(str(eni))==8
+
+    created = datetime.datetime.now()
+    modified = created+datetime.timedelta(seconds=10)
+    deleted = modified+datetime.timedelta(seconds=3)
+
+    ship = Ship(
+        ship_id, 
+        name, 
+        imo, 
+        callsign, 
+        participant_id,
+        length, 
+        width, 
+        is_tug, 
+        bollard_pull, 
+        eni, 
+        created, 
+        modified, 
+        deleted
+    )
+    return ship
+
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/shipcall.py b/src/lib_brecal_utils/brecal_utils/stubs/shipcall.py
new file mode 100644
index 0000000..6762692
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/stubs/shipcall.py
@@ -0,0 +1,81 @@
+import datetime
+from brecal_utils.stubs import generate_uuid1_int
+from BreCal.schemas.model import Shipcall
+from dataclasses import field
+
+def get_shipcall_simple():
+    # only used for the stub
+    base_time = datetime.datetime.now()
+
+    shipcall_id = generate_uuid1_int()
+    ship_id = generate_uuid1_int()
+
+    eta = base_time+datetime.timedelta(hours=3, minutes=12)
+    role_type = 1
+    voyage = "987654321"
+    etd = base_time+datetime.timedelta(hours=6, minutes=12) # should never be before eta
+
+    arrival_berth_id = generate_uuid1_int()
+    departure_berth_id = generate_uuid1_int()
+
+    tug_required = False
+    pilot_required = False
+
+    flags = 0 # #TODO_shipcall_flags. What is meant here? What should be tested?
+    pier_side = False # whether a ship will be fixated on the pier side. en: pier side, de: Anlegestelle. From 'BremenCalling_Datenmodell.xlsx': gedreht/ungedreht
+    bunkering = False # #TODO_bunkering_unclear
+    replenishing_terminal = False # en: replenishing terminal, de: Nachfüll-Liegeplatz
+    replenishing_lock = False # en: replenishing lock, de: Nachfüllschleuse
+
+    draft = 0.12 # #TODO_draft_value: clarify, what 'draft' means and what kind of values are to be expected
+
+    # tidal window: built in a way, where ETA and ETD are in-between the window
+    # #TODO_tidal_window_source: are these windows taken from a database or provided by the user? How do they know this?
+    tidal_window_from = base_time+datetime.timedelta(hours=2, minutes=12)
+    tidal_window_to = base_time+datetime.timedelta(hours=7, minutes=12)
+    rain_sensitive_cargo = False
+    recommended_tugs = 2 # assert 0<recommended_tugs<={threshold}. E.g., 20 should not be exceeded.
+    anchored = False
+    moored_lock = False # de: 'Festmacherschleuse', en: 'moored lock'
+
+    canceled = False
+    evaluation = None
+    evaluation_message = ""
+    created = datetime.datetime.now()
+    modified = created+datetime.timedelta(seconds=10)
+
+    participants = [generate_uuid1_int(), generate_uuid1_int(), generate_uuid1_int(), generate_uuid1_int()] # field(default_factory=[generate_uuid1_int(), generate_uuid1_int(), generate_uuid1_int(), generate_uuid1_int()]) # list
+
+    shipcall = Shipcall(
+        shipcall_id, 
+        ship_id, 
+        role_type,
+        eta, 
+        voyage, 
+        etd, 
+        arrival_berth_id, 
+        departure_berth_id, 
+        tug_required, 
+        pilot_required, 
+        flags, 
+        pier_side, 
+        bunkering, 
+        replenishing_terminal, 
+        replenishing_lock, 
+        draft, 
+        tidal_window_from, 
+        tidal_window_to, 
+        rain_sensitive_cargo, 
+        recommended_tugs, 
+        anchored, 
+        moored_lock, 
+        canceled, 
+        evaluation,
+        evaluation_message, 
+        created, 
+        modified, 
+        participants, 
+    )
+    return shipcall
+
+
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/times_agency.py b/src/lib_brecal_utils/brecal_utils/stubs/times_agency.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/times_full.py b/src/lib_brecal_utils/brecal_utils/stubs/times_full.py
new file mode 100644
index 0000000..8f9e0b1
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/stubs/times_full.py
@@ -0,0 +1,67 @@
+"""
+this stub creates an example time object, where the times of every role are present.
+users will thereby be able to modify these values
+"""
+import datetime
+from brecal_utils.stubs import generate_uuid1_int
+from BreCal.schemas.model import Times
+
+def get_times_full_simple():
+    # only used for the stub
+    base_time = datetime.datetime.now()
+
+    # note 1: eta and etd should never individually be in reverse order. assert etd>eta (for berth) & lock
+    # note 2: times are currently computed as a sequence of (eta_berth -> lock_time -> etd_berth -> zone_entry). The deltas are arbitrary
+    times_id = generate_uuid1_int()
+
+    eta_berth = base_time+datetime.timedelta(hours=1, minutes=12)
+    eta_berth_fixed = False
+
+    lock_time = eta_berth+datetime.timedelta(hours=0, minutes=50)
+    lock_time_fixed = False
+
+    etd_berth = lock_time+datetime.timedelta(hours=0, minutes=45)
+    etd_berth_fixed = False
+
+    zone_entry = etd_berth+datetime.timedelta(hours=0, minutes=15)
+    zone_entry_fixed = False
+
+    operations_start = zone_entry+datetime.timedelta(hours=1, minutes=30)
+    operations_end = operations_start+datetime.timedelta(hours=4, minutes=30)
+
+    remarks = "" # assert len(remarks)<{max_len_threshold}
+
+    participant_id = generate_uuid1_int()
+    shipcall_id = generate_uuid1_int()
+
+    berth_id = generate_uuid1_int()
+    berth_info = ""
+    pier_side = True
+    participant_type = None
+
+    created = datetime.datetime.now()
+    modified = created+datetime.timedelta(seconds=10)
+
+    times = Times(
+        id=times_id, 
+        eta_berth=eta_berth, 
+        eta_berth_fixed=eta_berth_fixed, 
+        etd_berth=etd_berth, 
+        etd_berth_fixed=etd_berth_fixed,
+        lock_time=lock_time,
+        lock_time_fixed=lock_time_fixed,
+        zone_entry=zone_entry,
+        zone_entry_fixed=zone_entry_fixed,
+        operations_start=operations_start,
+        operations_end=operations_end,
+        remarks=remarks, 
+        participant_id=participant_id,
+        berth_id=berth_id,
+        berth_info=berth_info,
+        pier_side=pier_side,
+        participant_type=participant_type,
+        shipcall_id=shipcall_id,
+        created=created,
+        modified=modified,
+    )   
+    return times
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/times_mooring.py b/src/lib_brecal_utils/brecal_utils/stubs/times_mooring.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/times_pilot.py b/src/lib_brecal_utils/brecal_utils/stubs/times_pilot.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/times_portauthority.py b/src/lib_brecal_utils/brecal_utils/stubs/times_portauthority.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/times_terminal.py b/src/lib_brecal_utils/brecal_utils/stubs/times_terminal.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/brecal_utils/stubs/user.py b/src/lib_brecal_utils/brecal_utils/stubs/user.py
new file mode 100644
index 0000000..12b8d2c
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/stubs/user.py
@@ -0,0 +1,35 @@
+import bcrypt
+import datetime
+from brecal_utils.stubs import generate_uuid1_int
+from BreCal.schemas.model import User
+
+
+def get_user_simple():
+    user_id = generate_uuid1_int()
+    participant_id = generate_uuid1_int() # should be taken from the database
+
+    first_name = "Max"
+    last_name = "Mustermann"
+    user_name = "maxm123"
+    user_email = "max.mustermann@brecal.de"
+    user_phone = "0173123456" # formatting?
+    password_hash = bcrypt.hashpw("123456".encode('utf-8'), bcrypt.gensalt( 12 )).decode('utf8')
+    api_key = bcrypt.hashpw("apikey123".encode('utf-8'), bcrypt.gensalt( 12 )).decode('utf8')
+
+    created = datetime.datetime.now()
+    modified = created+datetime.timedelta(seconds=10)
+
+    user = User(
+        user_id, 
+        participant_id, 
+        first_name, 
+        last_name, 
+        user_name, 
+        user_email,
+        user_phone,
+        password_hash,
+        api_key,
+        created,
+        modified
+    )
+    return user
\ No newline at end of file
diff --git a/src/lib_brecal_utils/brecal_utils/test_handling.py b/src/lib_brecal_utils/brecal_utils/test_handling.py
new file mode 100644
index 0000000..3757f0d
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/test_handling.py
@@ -0,0 +1,84 @@
+
+def execute_test_with_pytest(filepath):
+	"""
+	creates a subprocess to use 'pytest' on a script. Every function inside the filepath
+	will be tested individually. The function returns verbose information about the outcome.
+	
+	filepath:
+		can either be an individual .py file or a root directory, which contains multiple files
+	"""
+	import os
+	import pytest
+	from subprocess import Popen, PIPE
+	
+	assert os.path.exists(filepath), f"cannot find file {filepath}"
+
+	with Popen(['pytest',
+				'-v', 
+				'-W ignore::DeprecationWarning',
+				'-vv',
+				'--durations=0',
+				'--tb=short',  # shorter traceback format
+				str(filepath)], stdout=PIPE, bufsize=1, 
+			   universal_newlines=True) as p:
+		for line in p.stdout:
+			print(line, end='')
+	return
+	
+def execute_coverage_test(tests_path, coverage_path, cov_report_dst_dir=None, cov_fail_under_rate=80, is_test=0):
+	"""
+	creates a subprocess to use 'coverage' on a script. Every function inside the file
+	will be tested individually. The function returns verbose information about the outcome.
+	
+	this function needs two inputs:
+		tests_path, a path that locates each test that should be executed
+			e.g.: "/home/scope_sorting/brecal/src/lib_brecal_utils/tests"
+			
+		coverage_path, a path where the code is stored, which should be analyzed for coverage
+			e.g.: "/home/scope_sorting/brecal/src/lib_brecal_utils/brecal_utils"
+			
+	optional:
+		cov_report_dst_dir, which determines, where the coverage report will be stored. This function then
+		creates & stores an .html and .xml report in that folder. default: None
+		
+		cov_fail_under_rate, an integer which determines, when a coverage test should fail. Default: 80, meaning
+		that at least 80 % of the directory should be tested to pass the test.
+	"""
+	import os
+	import pytest
+	from subprocess import Popen, PIPE
+
+	assert os.path.exists(tests_path), f"cannot find root directory {tests_path}"
+	assert os.path.exists(coverage_path), f"cannot find root directory {coverage_path}"
+	
+	if cov_report_dst_dir is not None:
+		p_open_list_arguments = [
+			'pytest',
+			f"{str(tests_path)}", 
+			"-v",
+			"-vv",
+			"--durations=0",
+			"--cov-report=term",
+			f"--cov-report=html:{cov_report_dst_dir}",
+			f"--cov-report=xml:{cov_report_dst_dir}/coverage.xml",
+			f"--cov-fail-under={cov_fail_under_rate}",
+			f"--cov={str(coverage_path)}", 
+		]
+	else:
+		p_open_list_arguments = [
+			'pytest',
+			f"{str(tests_path)}", 
+			"-v",
+			"-vv",
+			"--durations=0",
+			"--cov-report=term",
+			f"--cov-fail-under={cov_fail_under_rate}",
+			f"--cov={str(coverage_path)}", 
+		]
+
+	with Popen(p_open_list_arguments, stdout=PIPE, bufsize=1,
+			universal_newlines=True) as p:
+		for line in p.stdout:
+			print(line, end='')
+			if is_test:
+				raise KeyboardInterrupt("is_test_interrupt")
diff --git a/src/lib_brecal_utils/brecal_utils/time_handling.py b/src/lib_brecal_utils/brecal_utils/time_handling.py
new file mode 100644
index 0000000..7571a67
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/time_handling.py
@@ -0,0 +1,21 @@
+import datetime
+
+def difference_to_then(event_time, tgt_time=None, make_absolute=False):
+    """
+    measures the difference between {tgt_time} and {event_time}. this function automatically converts the datetime.timedelta object to seconds. 
+    tgt_time defaults to {now}, if it is not specified.
+
+    Note: using divmod(time_diff, interval_duration) may be interesting to determine, how many units of {interval_duration} have passed.
+    e.g.,
+        divmod(time_diff, 3600) returns a float of hours. This will then return a tuple
+
+    options:
+        make_absolute: bool. Whether to return an absolute difference
+
+    Returns: time_diff (float)
+    """
+    tgt_time = tgt_time or datetime.datetime.now()
+    time_diff = tgt_time - event_time
+    if make_absolute:
+        return abs(time_diff.total_seconds())
+    return time_diff.total_seconds()
diff --git a/src/lib_brecal_utils/brecal_utils/validators/__init__.py b/src/lib_brecal_utils/brecal_utils/validators/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/brecal_utils/validators/input_validation.py b/src/lib_brecal_utils/brecal_utils/validators/input_validation.py
new file mode 100644
index 0000000..57200e8
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/validators/input_validation.py
@@ -0,0 +1,165 @@
+
+####################################### InputValidation #######################################
+
+from abc import ABC, abstractmethod
+from BreCal.schemas.model import Ship, Shipcall, Berth, User, Participant
+
+class InputValidation():
+    def __init__(self):
+        self.build_supported_models_dictionary()
+        return
+    
+    def build_supported_models_dictionary(self):
+        self.supported_models = {
+            Ship:ShipValidation(),
+            Shipcall:ShipcallValidation(),
+            Berth:BerthValidation(), 
+            User:UserValidation(), 
+            Participant:ParticipantValidation(),
+        }
+        return
+    
+    def assert_if_not_supported(self, dataclass_object):
+        assert type(dataclass_object) in self.supported_models, f"unsupported model. Found: {type(dataclass_object)}"
+        return
+    
+    def verify(self, dataclass_object):
+        self.assert_if_not_supported(dataclass_object)
+
+        # determine the type of the dataclass object. The internal dictionary 'supported_models' matches the dataclass object
+        # to the respective validation protocol
+        validator = self.supported_models.get(type(dataclass_object))
+
+        # check the object based on the rules within the matched validator
+        input_validation_state = validator.check(dataclass_object)
+        return input_validation_state
+
+
+class DataclassValidation(ABC):
+    """parent class of dataclas validators, which determines the outline of every object"""
+    def __init__(self):
+        return
+    
+    def check(self, dataclass_object) -> (list, bool):
+        """
+        the 'check' method provides a default style, how each dataclass object is validated. It returns a list of violations 
+        and a boolean, which determines, whether the check is passed successfully
+        """
+        all_rules = self.apply_all_rules(dataclass_object)
+        violations = self.filter_violations(all_rules)
+        input_validation_state = self.evaluate(violations)
+        return (violations, input_validation_state)
+    
+    @abstractmethod
+    def apply_all_rules(self, dataclass_object) -> list:
+        """
+        the 'apply_all_rules' method is mandatory for any dataclass validation object. It should execute all validation rules and
+        return a list of tuples, where each element is (output_boolean, validation_name)
+        """
+        all_rules = [(True, 'blank_validation_rule')]
+        return all_rules
+    
+    def filter_violations(self, all_rules):
+        """input: all_rules, a list of tuples, where each element is (output, validation_name), which are (bool, str). """
+        # if output is False, a violation is observed
+        violations = [result[1] for result in all_rules if not result[0]]
+        return violations
+    
+    def evaluate(self, violations) -> bool:
+        input_validation_state = len(violations)==0
+        return input_validation_state
+
+
+
+class ShipcallValidation(DataclassValidation):
+    """an object that validates a Shipcall dataclass object"""
+    def __init__(self):
+        super().__init__()
+        return
+    
+    def apply_all_rules(self, dataclass_object) -> list:
+        """apply all input validation rules to determine, whether there are violations. returns a list of tuples (output, validation_name)"""
+        raise NotImplementedError()
+        return all_rules
+
+
+from brecal_utils.validators.schema_validation import ship_bollard_pull_is_defined_or_is_not_tug, ship_bollard_pull_is_none_or_in_range, ship_callsign_len_is_seven_at_maximum, ship_eni_len_is_eight, ship_imo_len_is_seven, ship_length_in_range, ship_participant_id_is_defined_or_is_not_tug, ship_participant_id_is_none_or_int, ship_width_in_range
+# skip: ship_max_draft_is_defined_or_is_not_tug, ship_max_draft_is_none_or_in_range, 
+class ShipValidation(DataclassValidation):
+    """an object that validates a Ship dataclass object"""
+    def __init__(self):
+        super().__init__()
+        return
+    
+    def apply_all_rules(self, dataclass_object) -> list:
+        """apply all input validation rules to determine, whether there are violations. returns a list of tuples (output, validation_name)"""
+        # skip: ship_max_draft_is_defined_or_is_not_tug, ship_max_draft_is_none_or_in_range, 
+        """
+        #TODO_ship_max_draft
+        with pytest.raises(AttributeError, match="'Ship' object has no attribute 'max_draft'"):
+            assert ship_max_draft_in_range(ship)[0], f"max draft of a ship must be between 0 and 20 meters"
+            assert ship_max_draft_is_none_or_in_range(ship)[0], f"the max_draft should either be undefined or between 0 and 20 meters"
+        """
+
+        # list comprehension: every function becomes part of the loop and will be executed. Each function is wrapped and provides (output, validation_name)
+        all_rules = [
+            # tuple: (output, validation_name)
+            check_rule(dataclass_object)
+
+            for check_rule in [
+                ship_bollard_pull_is_defined_or_is_not_tug, 
+                ship_bollard_pull_is_none_or_in_range, 
+                ship_callsign_len_is_seven_at_maximum, 
+                ship_eni_len_is_eight, 
+                ship_imo_len_is_seven, 
+                ship_length_in_range, 
+                ship_participant_id_is_defined_or_is_not_tug, 
+                ship_participant_id_is_none_or_int, 
+                ship_width_in_range
+            ]
+        ]
+        return all_rules
+
+class BerthValidation(DataclassValidation):
+    """an object that validates a Berth dataclass object"""
+    def __init__(self):
+        super().__init__()
+        return
+    
+    def apply_all_rules(self, dataclass_object) -> list:
+        """apply all input validation rules to determine, whether there are violations. returns a list of tuples (output, validation_name)"""
+        raise NotImplementedError()
+        return all_rules
+
+class UserValidation(DataclassValidation):
+    """an object that validates a User dataclass object"""
+    def __init__(self):
+        super().__init__()
+        return
+    
+    def apply_all_rules(self, dataclass_object) -> list:
+        """apply all input validation rules to determine, whether there are violations. returns a list of tuples (output, validation_name)"""
+        raise NotImplementedError()
+        return all_rules
+
+from brecal_utils.validators.schema_validation import participant_postal_code_len_is_five
+class ParticipantValidation(DataclassValidation):
+    """an object that validates a Participant dataclass object"""
+    def __init__(self):
+        super().__init__()
+        return
+    
+    def apply_all_rules(self, dataclass_object) -> list:
+        """apply all input validation rules to determine, whether there are violations. returns a list of tuples (output, validation_name)"""
+
+        # list comprehension: every function becomes part of the loop and will be executed. Each function is wrapped and provides (output, validation_name)
+        all_rules = [
+            # tuple: (output, validation_name)
+            check_rule(dataclass_object)
+
+            for check_rule in [
+                participant_postal_code_len_is_five,
+            ]
+        ]
+        return all_rules
+    
diff --git a/src/lib_brecal_utils/brecal_utils/validators/schema_validation.py b/src/lib_brecal_utils/brecal_utils/validators/schema_validation.py
new file mode 100644
index 0000000..384b2f6
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/validators/schema_validation.py
@@ -0,0 +1,139 @@
+# wrapper: every validation function returns a tuple of (validation_state, validation_name)
+# example: validate_ship_eni_length might return the tuple (True, 'ship_eni_length')
+# thereby, one could always know, which test causes an issue
+
+####################################### general functions #######################################
+
+def validation_state_and_validation_name(validation_name):
+    """
+    can wrap arbitrary functions, so they return (output, validation_name)-tuples
+    usage example:
+        @validation_state_and_validation_name("ship_eni_length")
+        def validate_ship_eni_length(ship):
+            return length_matches_exactly(ship.eni,8)
+    """
+    def wrapper(validation_fct):
+        def decorated_fct(*args, **kwargs):
+            return (validation_fct(*args, **kwargs), validation_name)
+        return decorated_fct
+    return wrapper
+
+def value_in_range(query_value, start_range, end_range):
+    """determines, whether the query_value is greater than start_range, but smaller than end_range. Returns bool"""
+    return start_range<query_value<end_range
+
+def length_is_at_maximum(query_value, max_len):
+    """determines, whether the query_value's length is l<={max_len}. Returns bool"""
+    return len(str(query_value))<=max_len
+
+def length_matches_exactly(query_value, length_value):
+    """determines, whether the query_value's length is exactly l=={length_value}. Returns bool"""
+    return len(str(query_value)) == length_value
+
+
+
+
+####################################### dataclass specifics #######################################
+
+### Ship dataclass (BreCal.schema.model.Ship) ###
+
+@validation_state_and_validation_name("ship_bollard_pull_none_or_value_in_range")
+def ship_bollard_pull_is_none_or_in_range(ship):
+    """a ship should either have its bollard_pull between 0 and 500, or have an undefined bollard_pull (when not a tug)"""
+    return (ship.bollard_pull is None) or (value_in_range(ship.bollard_pull, 0, 500))
+
+@validation_state_and_validation_name("ship_max_draft_none_or_value_in_range")
+def ship_max_draft_is_none_or_in_range(ship):
+    """a ship should either have its max_draft between 0 and 20, or have an undefined max_draft (when not a tug)"""
+    return (ship.max_draft is None) or (value_in_range(ship.max_draft, 0, 20))
+
+@validation_state_and_validation_name("ship_participant_id_none_or_int")
+def ship_participant_id_is_none_or_int(ship):
+    """a ship should either have its participant_id defined (integer when ship is a tug), or have an undefined participant_id (when not a tug)"""
+    return isinstance(ship.participant_id, int) or (ship.participant_id is None)
+
+
+@validation_state_and_validation_name("ship_length")
+def ship_length_in_range(ship):
+    """ship length-values should be valid. between 0 and 500 meters is plausible. returns bool"""
+    return value_in_range(ship.length, 0, 500)
+
+@validation_state_and_validation_name("ship_width")
+def ship_width_in_range(ship):
+    """ship length-values should be valid. between 0 and 500 meters is plausible. returns bool"""
+    return value_in_range(ship.width, 0, 500)
+
+@validation_state_and_validation_name("ship_eni_length")
+def ship_eni_len_is_eight(ship):
+    """eni-no. are standardized. They should have exactly eight characters. returns bool"""
+    return length_matches_exactly(ship.eni,8)
+
+@validation_state_and_validation_name("ship_imo_length")
+def ship_imo_len_is_seven(ship):
+    """IMO-numbers are standardized. They should have exactly seven characters. returns bool"""
+    return length_matches_exactly(ship.imo,7)
+
+@validation_state_and_validation_name("ship_callsign_length")
+def ship_callsign_len_is_seven_at_maximum(ship):
+    """the ship's callsign should have l<=7 characters. returns bool"""
+    return length_is_at_maximum(ship.callsign, 7)
+
+
+def ship_is_not_tug_or_key_is_defined(is_tug, key_):
+    """ # base function
+    function that checks, if a Ship dataclass is either
+        a) not a tug
+        b) has a defined value of {key_}
+    can be used for max_draft, participant_id and bollard_pull
+    """
+    return (not is_tug) or (key_ is not None)
+
+@validation_state_and_validation_name("ship_bollard_pull_dynamically_mandatory")
+def ship_bollard_pull_is_defined_or_is_not_tug(ship):
+    """
+    there are two valid cases for the bollard_pull:
+        a) bollard_pull is undefined (None), if the ship is not a tug
+        b) bollard_pull is defined, if the ship is a tug
+    if the ship is a tug, a separate function validates in addition, if the value is in an accepted range
+
+    returns bool
+    """
+    return ship_is_not_tug_or_key_is_defined(ship.is_tug, ship.bollard_pull)
+
+@validation_state_and_validation_name("ship_max_draft_dynamically_mandatory")
+def ship_max_draft_is_defined_or_is_not_tug(ship):
+    """
+    there are two valid cases for the max_draft:
+        a) max_draft is undefined (None), if the ship is not a tug
+        b) max_draft is defined, if the ship is a tug
+    if the ship is a tug, a separate function validates in addition, if the value is in an accepted range
+
+    returns bool
+    """
+    return ship_is_not_tug_or_key_is_defined(ship.is_tug, ship.max_draft)
+
+# #TODO_ship_tug_participant_id: is this semantically correct? Will the participant_id be entered or automatically filled?
+@validation_state_and_validation_name("ship_max_draft_dynamically_mandatory")
+def ship_participant_id_is_defined_or_is_not_tug(ship):
+    """
+    there are two valid cases for the max_draft:
+        a) participant_id is undefined (None), if the ship is not a tug
+        b) participant_id is defined, if the ship is a tug
+
+    returns bool
+    """
+    return ship_is_not_tug_or_key_is_defined(ship.is_tug, ship.participant_id)
+
+
+
+### Participant dataclass (BreCal.schema.model.Participant) ###
+
+@validation_state_and_validation_name("participant_postal_code_length")
+def participant_postal_code_len_is_five(participant):
+    """
+    validates, that a postal code has 5 characters. returns bool
+
+    # #TODO_postal_code_length_validation: might make sense to request postal_code<=5 characters
+    # is the 5-character requirement true when international ships arive?
+    """
+    return length_matches_exactly(participant.postal_code, 5)
diff --git a/src/lib_brecal_utils/brecal_utils/validators/time_logic.py b/src/lib_brecal_utils/brecal_utils/validators/time_logic.py
new file mode 100644
index 0000000..b80384e
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/validators/time_logic.py
@@ -0,0 +1,91 @@
+import datetime
+import numpy as np
+import pandas as pd
+
+class TimeLogic():
+    def __init__(self):
+        return
+    
+    def time_delta(self, src_time, tgt_time, unit:str="m"):
+        """
+        in brief, this function measures tgt_time - src_time
+
+        if the tgt_time is in the future, it is a positive value (tgt_time > src_time)
+        if the tgt_time is in the past, it is a negative value (tgt_time < src_time)
+
+        returns the delta between tgt_time and src_time as a float of minutes (or the optionally provided unit)
+
+        options:
+            unit: str, which defaults to 'm' (minutes). 'h' (hours) or 's' (seconds) are also common units. Determines the unit of the output time delta
+        """
+        # convert np.datetime64
+        if isinstance(src_time, pd.Timestamp):
+            src_time = src_time.to_datetime64()
+
+        if isinstance(tgt_time, pd.Timestamp):
+            tgt_time = tgt_time.to_datetime64()
+
+        if isinstance(src_time, datetime.datetime):
+            src_time = np.datetime64(src_time)
+
+        if isinstance(tgt_time, datetime.datetime):
+            tgt_time = np.datetime64(tgt_time)
+
+        delta = tgt_time - src_time
+        minute_delta = delta / np.timedelta64(1, unit)
+        return minute_delta
+    
+    def time_delta_from_now_to_tgt(self, tgt_time, unit="m"):
+        return self.time_delta(datetime.datetime.now(), tgt_time=tgt_time, unit=unit)
+    
+    def time_inbetween(self, query_time:datetime.datetime, start_time:datetime.datetime, end_time:datetime.datetime) -> bool:
+        """
+        checks, whether the query time is inbetween the start & end time. Returns a bool to indicate that.
+
+        Example:
+            a = datetime.datetime(2017, 5, 16, 8, 21, 10)
+            b = datetime.datetime(2017, 5, 17, 8, 21, 10)
+            c = datetime.datetime(2017, 5, 18, 8, 21, 10)
+
+            is b between a and c? -> yes. Returns True
+            is c between a and b? -> no. Returns False
+
+        returns bool
+        """
+        assert isinstance(query_time, datetime.datetime)
+        assert isinstance(start_time, datetime.datetime)
+        assert isinstance(end_time, datetime.datetime)
+
+        return start_time <= query_time <= end_time
+    
+    def time_inbetween_absolute_delta(self, query_time:datetime.datetime, start_time:datetime.datetime, end_time:datetime.datetime) -> tuple:
+        """
+        similarly to self.time_inbetween, this function compares a query_time with the provided start and end time.
+        however, this function instead returns timedelta objects, which show the difference towards start and end
+
+        this function applies abs() to return only absolute deviations. Thereby, -23 becomes +23
+
+        returns: tuple(absolute_start_delta, absolute_end_delta)
+        """
+        return (abs(query_time-start_time), abs(query_time-end_time))
+    
+    def compare_query_is_inbetween_list(self, query_time, list_of_other_times) -> list:
+        list_of_bools = [
+            self.time_inbetween(query_time, time_elem_begin, time_elem_end)
+            for (time_elem_begin, time_elem_end) in list_of_other_times
+        ]
+        return list_of_bools
+    
+    def query_time_any_inbetween(self, query_time, list_of_other_times):
+        """
+        given a query_time element, the element will be compared to every element in a list, where each
+        element is a tuple of (start_time, end_time)
+        """
+        if len(list_of_other_times)==0:
+            # the time is not inbetween, if the provided list is empty
+            return False
+        
+        list_of_bools = self.compare_query_is_inbetween_list(query_time, list_of_other_times)
+        return np.any(list_of_bools), list_of_bools
+
+    
diff --git a/src/lib_brecal_utils/brecal_utils/validators/validation_rule_functions.py b/src/lib_brecal_utils/brecal_utils/validators/validation_rule_functions.py
new file mode 100644
index 0000000..39a34c7
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/validators/validation_rule_functions.py
@@ -0,0 +1,763 @@
+import inspect
+import types
+from brecal_utils.database.enums import ParticipantType, ShipcallType, ParticipantwiseTimeDelta
+import numpy as np
+import pandas as pd
+from brecal_utils.validators.time_logic import TimeLogic
+from brecal_utils.database.enums import StatusFlags
+#from brecal_utils.validators.schema_validation import validation_state_and_validation_name
+
+
+class ValidationRuleBaseFunctions():
+    """
+    Base object with individual functions, which the {ValidationRuleFunctions}-child refers to.
+    This parent class provides base functions and helps to restructure the code in a more comprehensible way.
+    """
+    def __init__(self, sql_handler):
+        self.sql_handler = sql_handler
+        self.time_logic = TimeLogic()
+
+    def check_time_delta_violation_query_time_to_now(self, query_time:pd.Timestamp, key_time:pd.Timestamp, threshold:float)->bool:
+        """
+        # base function for all validation rules in the group {0001} A-L
+
+        measures the time between NOW and query_time. 
+        When the query_time lays in the past, the delta is negative
+        when the query_time lays in the future, the delta is positive
+
+        returns a violation state depending on whether the delta is
+            Violation, if: 0 >= delta > threshold
+
+        When the key time is defined (not None), there is no violation. Returns False
+
+        options:
+            query_time: will be used to measure the time difference of 'now' until the query time
+            key_time: will be used to check, whether the respective key already has a value
+            threshold: threshold where a time difference becomes crucial. When the delta is below the threshold, a violation might occur
+        """
+        # rule is not applicable -> return 'GREEN'
+        if key_time is not None:
+            return False
+        
+        # otherwise, this rule applies and the difference between 'now' and the query time is measured
+        delta = self.time_logic.time_delta_from_now_to_tgt(tgt_time=query_time, unit="m")
+
+        # a violation occurs, when the delta (in minutes) exceeds the specified threshold of a participant
+        # to prevent past-events from triggering violations, negative values are ignored
+        # Violation, if 0 >= delta >= threshold
+        violation_state = (delta >= 0) and (delta<=threshold)
+        return violation_state
+    
+    def check_participants_agree_on_estimated_time(self, shipcall, query, df_times, applicable_shipcall_type)->bool:
+        """
+        # base function for all validation rules in the group {0002} A-C
+
+        compares, whether the participants agree on the estimated time (of arrival or departure), depending on
+        whether the shipcall type is incoming, outgoing or shifting.
+
+        No violations are observed, when
+            - the shipcall belongs to a different type than the rule expects
+            - there are no matching times for the provided {query} (e.g., "eta_berth")
+            
+        Instead of comparing each individual result, this function counts the amount of unique instances.
+        When there is not only one unique value, there are deviating time estimates, and a violation occurs
+
+        returns: violation_state (bool)
+        """
+        # shipcall type filter: consider only shipcalls, where the type matches
+        if shipcall.type != applicable_shipcall_type.value:
+            violation_state = False
+            return violation_state
+
+        # filter by participant types of interest (agency, mooring, portauthority/administration, pilot, tug)
+        participant_types = [ParticipantType.AGENCY.value, ParticipantType.MOORING.value, ParticipantType.PORT_ADMINISTRATION.value, ParticipantType.PILOT.value, ParticipantType.TUG.value]
+        df_times = df_times.loc[df_times["participant_type"].isin(participant_types),:]
+
+        # exclude missing entries
+        df_times.loc[~df_times[query].isnull(),:]
+
+        # when there are no entries left (no entries are provided), skip
+        if len(df_times)==0:
+            violation_state = False
+            return violation_state
+
+        # there should only be one eta_berth, when all participants have provided the same time
+        # this equates to the same criteria as checking, whether
+        #    times_agency.eta_berth==times_mooring.eta_berth==times_portadministration.eta_berth==times_pilot.eta_berth==times_tug.eta_berth
+        unique_times = len(pd.unique(df_times.loc[:,query]))
+        violation_state = unique_times!=1
+        return violation_state
+    
+    def check_unique_shipcall_counts(self, query:str, rounding="min", maximum_threshold=3)->bool:
+        """
+        # base function for all validation rules in the group {0005} A&B
+
+        compares how many unique times are found for the provided {query} (e.g., "eta_berth")
+        This function rounds the results, counts the unique values and returns a boolean state, whether the {maximum_threshold} is exceeded
+        """
+        # filter the df: keep only times_agents
+        # filter out all NaN and NaT entries
+        times_agency = self.sql_handler.get_times_for_agency(non_null_column=query)
+
+        # get values and optionally round the values
+        (values, unique, counts) = self.sql_handler.get_unique_ship_counts(all_df_times=times_agency, query=query, rounding=rounding, maximum_threshold=maximum_threshold)
+
+        # when ANY of the unique values exceeds the threshold, a violation is observed
+        violation_state = np.any(np.greater(counts, maximum_threshold))
+        return violation_state
+
+
+class ValidationRuleFunctions(ValidationRuleBaseFunctions):
+    """
+    an accumulation object that makes sure, that any validation rule is translated to a function with default naming convention and 
+    return types. Each function should return a ValidationRuleState enumeration object and a description string to which validation rule
+    the result belongs. These are returned as tuples (ValidationRuleState, validation_name)
+    Each rule should have the same input arguments (self, shipcall, df_times, *args, **kwargs)
+
+    The object makes heavy use of calls from an SQLHandler object, which provides functions for dataframe access and filtering.
+    
+    each validation_name is generated by calling the function inside a method
+        validation_name = inspect.currentframe().f_code.co_name # validation_name then returns the name of the method from where 'currentframe()' was called.
+
+    # example:
+    #def validation_rule_fct_example(self, shipcall, df_times):
+        #validation_name = inspect.currentframe().f_code.co_name
+        #return (ValidationRuleState.NONE, validation_name)
+    """
+    def __init__(self, sql_handler):
+        super().__init__(sql_handler)
+        return 
+    
+    def get_validation_rule_functions(self):
+        """return a list of all methods in this object, which are all validation rule functions."""
+        return [self.__getattribute__(mthd_) for mthd_ in dir(self) if ('validation_rule_fct' in mthd_) and (isinstance(self.__getattribute__(mthd_), types.MethodType))]
+    
+    def validation_rule_fct_missing_time_agency_berth_eta(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-A
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-A:
+            - Checks, if times_agency.eta_berth is filled in. 
+            - Measures the difference between 'now' and 'shipcall.eta'.
+        """
+        # check, if the header is filled in (agency)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value])]) != 1:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        query_time = shipcall.eta
+        key_time = times_agency.eta_berth
+        threshold = ParticipantwiseTimeDelta.AGENCY
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_agency_berth_etd(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-B
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-B:
+            - Checks, if times_agency.etd_berth is filled in. 
+            - Measures the difference between 'now' and 'shipcall.etd'.
+        """
+        # check, if the header is filled in (agency)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value])]) != 1:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        query_time = shipcall.etd
+        key_time = times_agency.etd_berth
+        threshold = ParticipantwiseTimeDelta.AGENCY
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_mooring_berth_eta(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-C
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-C:
+            - Checks, if times_mooring.eta_berth is filled in. 
+            - Measures the difference between 'now' and 'times_agency.eta_berth'.
+        """
+        # check, if the header is filled in (agency & MOORING)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.MOORING.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_mooring = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.MOORING.value)
+
+        query_time = times_agency.eta_berth
+        key_time = times_mooring.eta_berth
+        threshold = ParticipantwiseTimeDelta.MOORING
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_mooring_berth_etd(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-D
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-D:
+            - Checks, if times_mooring.etd_berth is filled in. 
+            - Measures the difference between 'now' and 'times_agency.etd_berth'.
+        """
+        # check, if the header is filled in (agency & MOORING)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.MOORING.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_mooring = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.MOORING.value)
+
+        query_time = times_agency.etd_berth
+        key_time = times_mooring.etd_berth
+        threshold = ParticipantwiseTimeDelta.MOORING
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_portadministration_berth_eta(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-F
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-F:
+            - Checks, if times_port_administration.eta_berth is filled in. 
+            - Measures the difference between 'now' and 'times_agency.eta_berth'.
+        """
+        # check, if the header is filled in (agency & PORT_ADMINISTRATION)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.PORT_ADMINISTRATION.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_port_administration = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.PORT_ADMINISTRATION.value)
+
+        query_time = times_agency.eta_berth
+        key_time = times_port_administration.eta_berth
+        threshold = ParticipantwiseTimeDelta.PORT_ADMINISTRATION
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_portadministration_berth_etd(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-G
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-G:
+            - Checks, if times_port_administration.etd_berth is filled in. 
+            - Measures the difference between 'now' and 'times_agency.etd_berth'.
+        """
+        # check, if the header is filled in (agency & PORT_ADMINISTRATION)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.PORT_ADMINISTRATION.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_port_administration = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.PORT_ADMINISTRATION.value)
+
+        query_time = times_agency.etd_berth
+        key_time = times_port_administration.etd_berth
+        threshold = ParticipantwiseTimeDelta.PORT_ADMINISTRATION
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_pilot_berth_eta(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-H
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-H:
+            - Checks, if times_pilot.eta_berth is filled in. 
+            - Measures the difference between 'now' and 'times_agency.eta_berth'.
+        """
+        # check, if the header is filled in (agency & PILOT)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.PILOT.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_pilot = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.PILOT.value)
+
+        query_time = times_agency.eta_berth
+        key_time = times_pilot.eta_berth
+        threshold = ParticipantwiseTimeDelta.PILOT
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+        
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_pilot_berth_etd(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-I
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-I:
+            - Checks, if times_pilot.etd_berth is filled in. 
+            - Measures the difference between 'now' and 'times_agency.etd_berth'.
+        """
+        # check, if the header is filled in (agency & PILOT)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.PILOT.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_pilot = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.PILOT.value)
+
+        query_time = times_agency.etd_berth
+        key_time = times_pilot.etd_berth
+        threshold = ParticipantwiseTimeDelta.PILOT
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+        
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_tug_berth_eta(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-J
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-J:
+            - Checks, if times_tug.eta_berth is filled in. 
+            - Measures the difference between 'now' and 'times_agency.eta_berth'.
+        """
+        # check, if the header is filled in (agency & TUG)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.TUG.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_tug = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.TUG.value)
+
+        query_time = times_agency.eta_berth
+        key_time = times_tug.eta_berth
+        threshold = ParticipantwiseTimeDelta.TUG
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+        
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_tug_berth_etd(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-K
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-K:
+            - Checks, if times_tug.etd_berth is filled in. 
+            - Measures the difference between 'now' and 'times_agency.etd_berth'.
+        """
+        # check, if the header is filled in (agency & TUG)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.TUG.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_tug = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.TUG.value)
+
+        query_time = times_agency.etd_berth
+        key_time = times_tug.etd_berth
+        threshold = ParticipantwiseTimeDelta.TUG
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+        
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_terminal_berth_eta(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-L
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-L:
+            - Checks, if times_terminal.eta_berth is filled in. 
+            - Measures the difference between 'now' and 'times_agency.eta_berth'.
+        """
+        # check, if the header is filled in (agency & terminal)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.TERMINAL.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_terminal = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.TERMINAL.value)
+
+        query_time = times_agency.eta_berth
+        key_time = times_terminal.eta_berth
+        threshold = ParticipantwiseTimeDelta.TERMINAL
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+        
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_missing_time_terminal_berth_etd(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0001-K
+        Type: Local Rule
+        Description: this validation checks, whether there is a missing time. When the difference between an event (e.g., the shipcall eta) is below
+        a certain threshold (e.g., 20 hours), a violation occurs
+
+        0001-K:
+            - Checks, if times_terminal.etd_berth is filled in. 
+            - Measures the difference between 'now' and 'times_agency.etd_berth'.
+        """
+        # check, if the header is filled in (agency & terminal)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.TERMINAL.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # preparation: obtain the correct times of the participant, define the query time and the key time
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_terminal = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.TERMINAL.value)
+
+        query_time = times_agency.etd_berth
+        key_time = times_terminal.etd_berth
+        threshold = ParticipantwiseTimeDelta.TERMINAL
+        violation_state = self.check_time_delta_violation_query_time_to_now(query_time=query_time, key_time=key_time, threshold=threshold)
+        
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+
+    
+    def validation_rule_fct_shipcall_incoming_participants_disagree_on_eta(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0002-A
+        Type: Local Rule
+        Description: this validation checks, whether the participants expect different ETA times
+        Filter: only applies to incoming shipcalls
+        """
+        query = "eta_berth"
+        
+        violation_state = self.check_participants_agree_on_estimated_time(
+            shipcall = shipcall, 
+
+            query=query, 
+            df_times=df_times, 
+            applicable_shipcall_type=ShipcallType.INCOMING
+            )
+        
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.RED, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_shipcall_outgoing_participants_disagree_on_etd(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0002-B
+        Type: Local Rule
+        Description: this validation checks, whether the participants expect different ETA times
+        Filter: only applies to outgoing shipcalls
+        """
+        query = "etd_berth"
+        
+        violation_state = self.check_participants_agree_on_estimated_time(
+            shipcall = shipcall, 
+
+            query=query, 
+            df_times=df_times, 
+            applicable_shipcall_type=ShipcallType.OUTGOING
+            )
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.RED, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_shipcall_shifting_participants_disagree_on_eta_or_etd(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0002-C
+        Type: Local Rule
+        Description: this validation checks, whether the participants expect different ETA or ETD times
+        Filter: only applies to shifting shipcalls
+        """
+        violation_state_eta = self.check_participants_agree_on_estimated_time(
+            shipcall = shipcall, 
+
+            query="eta_berth", 
+            df_times=df_times, 
+            applicable_shipcall_type=ShipcallType.SHIFTING
+            )
+        
+        violation_state_etd = self.check_participants_agree_on_estimated_time(
+            shipcall = shipcall, 
+
+            query="etd_berth", 
+            df_times=df_times, 
+            applicable_shipcall_type=ShipcallType.SHIFTING
+            )
+        
+        # apply 'eta_berth' check
+        # apply 'etd_berth'
+        # violation: if either 'eta_berth' or 'etd_berth' is violated
+        # functionally, this is the same as individually comparing all times for the participants
+        #    times_agency.eta_berth==times_mooring.eta_berth==times_portadministration.eta_berth==times_pilot.eta_berth==times_tug.eta_berth
+        #    times_agency.etd_berth==times_mooring.etd_berth==times_portadministration.etd_berth==times_pilot.etd_berth==times_tug.etd_berth
+        violation_state = (violation_state_eta) or (violation_state_etd)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.RED, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_eta_time_not_in_operation_window(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0003-A
+        Type: Local Rule
+        Description: this validation checks, whether the ETA time is between the provided operations window of the terminal
+
+        query time: eta_berth (times_agency)
+        start_time & end_time: operations_start & operations_end (times_terminal)
+        """
+        # check, if the header is filled in (agency & terminal)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.TERMINAL.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # get agency & terminal times
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY)
+        times_terminal = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.TERMINAL)
+
+        if (times_terminal.operations_end is pd.NaT) or (times_agency.etd_berth is pd.NaT):
+            return (StatusFlags.GREEN, None)
+
+        # check, whether the start of operations is AFTER the estimated arrival time
+        violation_state = times_terminal.operations_start<times_agency.eta_berth
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.RED, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_eta_time_not_in_operation_window(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0003-B
+        Type: Local Rule
+        Description: this validation checks, whether the ETD time is between the provided operations window of the terminal
+
+        query time: eta_berth (times_agency)
+        start_time & end_time: operations_start & operations_end (times_terminal)
+        """
+        # check, if the header is filled in (agency & terminal)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.TERMINAL.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        # get agency & terminal times
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY)
+        times_terminal = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.TERMINAL)
+
+        if (times_terminal.operations_end is pd.NaT) or (times_agency.etd_berth is pd.NaT):
+            return (StatusFlags.GREEN, None)
+
+        # check, whether the end of operations is AFTER the estimated departure time
+        violation_state = times_terminal.operations_end > times_agency.etd_berth
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.RED, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_eta_time_not_in_tidal_window(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0004-A
+        Type: Local Rule
+        Description: this validation checks, whether the ETA time is between the provided tidal window
+
+        query time: eta_berth (times_agency)
+        start_time & end_time: tidal_window_from & tidal_window_to (shipcall)
+        """
+        # check, if the header is filled in (agency)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value])]) != 1:
+            return (StatusFlags.GREEN, None)
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY)
+
+        # requirements: tidal window (from & to) is filled in
+        if (shipcall.tidal_window_from is pd.NaT) or (shipcall.tidal_window_to is pd.NaT) or (df_times.eta_berth is pd.NaT):
+            return (StatusFlags.GREEN, None)
+
+        # check, whether the query time is between start & end time
+        # a violation is observed, when the is NOT between start & end
+        violation_state = not self.time_logic.time_inbetween(query_time=times_agency.eta_berth, start_time=shipcall.tidal_window_from, end_time=shipcall.tidal_window_to)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.RED, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_etd_time_not_in_tidal_window(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0004-B
+        Type: Local Rule
+        Description: this validation checks, whether the ETD time is between the provided tidal window
+
+        query time: eta_berth (times_agency)
+        start_time & end_time: tidal_window_from & tidal_window_to (shipcall)
+        """
+        # check, if the header is filled in (agency)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value])]) != 1:
+            return (StatusFlags.GREEN, None)
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY)
+
+        # requirements: tidal window (from & to) is filled in
+        if (shipcall.tidal_window_from is pd.NaT) or (shipcall.tidal_window_to is pd.NaT) or (df_times.eta_berth is pd.NaT):
+            return (StatusFlags.GREEN, None)
+
+        # check, whether the query time is between start & end time
+        # a violation is observed, when the is NOT between start & end
+        violation_state = not self.time_logic.time_inbetween(query_time=times_agency.etd_berth, start_time=shipcall.tidal_window_from, end_time=shipcall.tidal_window_to)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.RED, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_too_many_identical_eta_times(self, shipcall, df_times, rounding = "min", maximum_threshold = 3, *args, **kwargs):
+        """
+        Code: #0005-A
+        Type: Global Rule
+        Description: this validation rule checks, whether there are too many shipcalls with identical ETA times.
+        """
+        # when ANY of the unique values exceeds the threshold, a violation is observed
+        query = "eta_berth"
+        violation_state = self.check_unique_shipcall_counts(query, rounding=rounding, maximum_threshold=maximum_threshold)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_too_many_identical_etd_times(self, shipcall, df_times, rounding = "min", maximum_threshold = 3, *args, **kwargs):
+        """
+        Code: #0005-B
+        Type: Global Rule
+        Description: this validation rule checks, whether there are too many shipcalls with identical ETD times.
+        """
+        # when ANY of the unique values exceeds the threshold, a violation is observed
+        query = "etd_berth"
+        violation_state = self.check_unique_shipcall_counts(query, rounding=rounding, maximum_threshold=maximum_threshold)
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_agency_and_terminal_berth_id_disagreement(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0006-A
+        Type: Local Rule
+        Description: This validation rule checks, whether agency and terminal agree with their designated berth place by checking berth_id.
+        """
+        # check, if the header is filled in (agency & terminal)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.TERMINAL.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_terminal = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.TERMINAL.value)
+
+        violation_state = times_agency.berth_id!=times_terminal.berth_id
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+    
+    def validation_rule_fct_agency_and_terminal_pier_side_disagreement(self, shipcall, df_times, *args, **kwargs):
+        """
+        Code: #0006-B
+        Type: Local Rule
+        Description: This validation rule checks, whether agency and terminal agree with their designated pier side by checking pier_side.
+        """
+        # check, if the header is filled in (agency & terminal)
+        if len(df_times.loc[df_times["participant_type"].isin([ParticipantType.AGENCY.value, ParticipantType.TERMINAL.value])]) != 2:
+            return (StatusFlags.GREEN, None)
+        
+        times_agency = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.AGENCY.value)
+        times_terminal = self.sql_handler.get_times_for_participant_type(df_times, participant_type=ParticipantType.TERMINAL.value)
+
+        violation_state = times_agency.pier_side!=times_terminal.pier_side
+
+        if violation_state:
+            validation_name = inspect.currentframe().f_code.co_name
+            return (StatusFlags.YELLOW, validation_name)
+        else:
+            return (StatusFlags.GREEN, None)
+
+
diff --git a/src/lib_brecal_utils/brecal_utils/validators/validation_rules.py b/src/lib_brecal_utils/brecal_utils/validators/validation_rules.py
new file mode 100644
index 0000000..3ee7a46
--- /dev/null
+++ b/src/lib_brecal_utils/brecal_utils/validators/validation_rules.py
@@ -0,0 +1,127 @@
+import copy
+import numpy as np
+import pandas as pd
+from brecal_utils.database.enums import StatusFlags
+from brecal_utils.validators.validation_rule_functions import ValidationRuleFunctions
+from BreCal.schemas.model import Shipcall
+
+
+class ValidationRules(ValidationRuleFunctions):
+    """
+    An object that determines the traffic light state for validation and notification. The provided feedback ('green', 'yellow', 'red')
+    determines, whether the state is critical. It uses ValidationRuleState enumerations.
+        In case of a critical validation state, the user's input prompt may be interrupted and the user may be warned.
+        In case of a critical notification state, the respective users will be automatically notified after n seconds. (#TODO_n_seconds_delay)
+    """
+    def __init__(self, sql_handler): # use the entire data that is provided for this query (e.g., json input)
+        super().__init__(sql_handler)
+
+        self.validation_state = self.determine_validation_state()
+        # currently flagged: notification_state initially was based on using one ValidationRules object for each query. This is deprecated.
+        # self.notification_state = self.determine_notification_state() # (state:str, should_notify:bool)
+        return
+    
+    def evaluate(self, shipcall):
+        """
+        1.) prepare df_times, which every validation rule tends to use
+            calling this only once saves a lot of computational overhead
+        2.) apply all validation rules
+        returns: (evaluation_state, violations)
+        """
+        # prepare df_times, which every validation rule tends to use
+        df_times = self.sql_handler.df_dict.get('times') # -> pd.DataFrame
+
+        # filter by shipcall id
+        df_times = self.sql_handler.get_times_of_shipcall(shipcall)
+
+        # apply all validation rules
+        # list of tuples, where each element is (state, msg)
+        evaluation_results = [elem(shipcall, df_times) for elem in self.get_validation_rule_functions()]
+
+        # filter out all 'None' results, which indicate that no violation occured.
+        evaluation_results = [evaluation_result for evaluation_result in evaluation_results if evaluation_result[1] is not None]
+
+        """ # deprecated
+        # check, if ANY of the evaluation results (evaluation_state) is larger than the .GREEN state. This means, that .YELLOW and .RED
+        # would return 'True'. Numpy arrays and functions are used to accelerate the comparison. 
+        # np.any returns a boolean. 
+        #evaluation_state = not np.any(np.greater(np.array([result[0] for result in evaluation_results]), ValidationRuleState.GREEN))
+        """
+        # check, what the maximum state flag is and return it
+        evaluation_state = np.max(np.array([result[0] for result in evaluation_results])) if len(evaluation_results)>0 else 1
+        return (evaluation_state, evaluation_results)
+    
+    def evaluation_verbosity(self, evaluation_state, evaluation_results):
+        """This function suggestions verbosity for the evaluation results. Based on 'True'/'False' evaluation outcome, the returned string is different."""
+        if evaluation_state:
+            return f"OK! The validation was successful. There are no rule violations."
+        else:
+            verbose_string = "These are:" + "\n\t".join(evaluation_results) # every element of the list will be displayed in a new line with a tab
+            return f"FAILED VALIDATION. There have been {len(evaluation_results)} violations. {verbose_string}"
+        
+    def evaluate_shipcall_from_df(self, x):
+        shipcall = Shipcall(**{**{'id':x.name}, **x.to_dict()})
+        evaluation_state, violations = self.evaluate(shipcall)
+        return evaluation_state, violations
+        
+    def evaluate_shipcalls(self, shipcall_df:pd.DataFrame)->pd.DataFrame:
+        """apply 'evaluate_shipcall_from_df' to each individual shipcall in {shipcall_df}. Returns shipcall_df ('evaluation' and 'evaluation_message' are updated)"""
+        results = shipcall_df.apply(lambda x: self.evaluate_shipcall_from_df(x), axis=1).values
+
+        # unbundle individual results. evaluation_state becomes an integer, violation 
+        evaluation_state = [StatusFlags(res[0]).value for res in results]
+        violations = [",".join(res[1]) if len(res[1])>0 else None for res in results]
+
+        shipcall_df.loc[:,"evaluation"] = evaluation_state
+        shipcall_df.loc[:,"evaluation_message"] = violations
+        return shipcall_df
+            
+    def determine_validation_state(self) -> str:
+        """
+        this method determines the validation state of a shipcall. The state is either ['green', 'yellow', 'red'] and signals,
+        whether an entry causes issues within the workflow of users. 
+        
+        returns: validation_state_new (str)
+        """
+        (validation_state_new, description) = self.undefined_method()
+        # should there also be notifications for critical validation states? In principle, the traffic light itself provides that notification. 
+        self.validation_state = validation_state_new
+        return validation_state_new
+    
+    def determine_notification_state(self) -> (str, bool):
+        """
+        this method determines state changes in the notification state. When the state is changed to yellow or red,
+        a user is notified about it. The only exception for this rule is when the state was yellow or red before,
+        as the user has then already been notified. 
+
+        returns: notification_state_new (str), should_notify (bool)
+        """
+        (state_new, description) = self.undefined_method() # determine the successor
+        should_notify = self.identify_notification_state_change(state_new)
+        self.notification_state = state_new # overwrite the predecessor
+        return state_new, should_notify
+    
+    def identify_notification_state_change(self, state_new) -> bool:
+        """
+        determines, whether the observed state change should trigger a notification. 
+        internally, this function maps a color string to an integer and determines, if the successor state is more severe than the predecessor.
+
+        state changes trigger a notification in the following cases:
+            green -> yellow
+            green -> red
+            yellow -> red
+
+            (none -> yellow) or (none -> red)
+            due to the values in the enumeration objects, the states are mapped to provide this function.
+            green=1, yellow=2, red=3, none=1. Hence, critical changes can be observed by simply checking with "greater than". 
+
+        returns bool, whether a notification should be triggered
+        """
+        # state_old is always considered at least 'Green' (1)
+        state_old = max(copy.copy(self.notification_state) if "notification_state" in list(self.__dict__.keys()) else StatusFlags.NONE, StatusFlags.GREEN.value)
+        return state_new.value > state_old.value
+    
+    def undefined_method(self) -> str:
+        """this function should apply the ValidationRules to the respective .shipcall, in regards to .times"""
+        # #TODO_traffic_state
+        return (StatusFlags.GREEN, False) # (state:str, should_notify:bool)
diff --git a/src/lib_brecal_utils/setup.py b/src/lib_brecal_utils/setup.py
new file mode 100644
index 0000000..44b0590
--- /dev/null
+++ b/src/lib_brecal_utils/setup.py
@@ -0,0 +1,13 @@
+from setuptools import find_packages, setup
+
+package_name = "brecal_utils"
+
+exec(open(f'{package_name}/_version.py').read()) # obtains __version__
+setup(
+    name=package_name,
+    packages=find_packages(),
+    version=__version__,
+    description='initializing the library. testing initial imports and relations. the license type is to be determined',
+    author='Max Metz',
+    license='to be determined',
+)
diff --git a/src/lib_brecal_utils/tests/__init__.py b/src/lib_brecal_utils/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/tests/stubs/__init__.py b/src/lib_brecal_utils/tests/stubs/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/tests/stubs/test_stub_objects.py b/src/lib_brecal_utils/tests/stubs/test_stub_objects.py
new file mode 100644
index 0000000..ccd1655
--- /dev/null
+++ b/src/lib_brecal_utils/tests/stubs/test_stub_objects.py
@@ -0,0 +1,60 @@
+import pytest
+
+def test_build_stub_berth():
+    from BreCal.schemas.model import Berth
+    from brecal_utils.stubs.berth import get_berth_simple
+    berth = get_berth_simple()
+    assert isinstance(berth, Berth)
+    return
+
+def test_build_stub_participant():
+    from BreCal.schemas.model import Participant
+    from brecal_utils.stubs.participant import get_participant_simple
+    participant = get_participant_simple()
+    assert isinstance(participant, Participant)
+    return
+
+def test_build_stub_user():
+    from BreCal.schemas.model import User
+    from brecal_utils.stubs.user import get_user_simple
+    user = get_user_simple()
+    assert isinstance(user, User)
+    return
+
+def test_build_stub_ship():
+    from BreCal.schemas.model import Ship
+    from brecal_utils.stubs.ship import get_ship_simple
+    ship = get_ship_simple()
+    assert isinstance(ship, Ship)
+    return
+
+def test_build_stub_shipcall():
+    from BreCal.schemas.model import Shipcall
+    from brecal_utils.stubs.shipcall import get_shipcall_simple
+    shipcall = get_shipcall_simple()
+    assert isinstance(shipcall, Shipcall)
+    return
+
+def test_build_stub_times():
+    from BreCal.schemas.model import Times
+    from brecal_utils.stubs.times_full import get_times_full_simple
+    times = get_times_full_simple()
+    assert isinstance(times, Times)
+    return
+
+def test_build_stub_notification():
+    from BreCal.schemas.model import Notification
+    from brecal_utils.stubs.notification import get_notification_simple
+    notification = get_notification_simple()
+    assert isinstance(notification, Notification)
+
+if __name__=="__main__":
+    test_build_stub_berth()
+    test_build_stub_participant()
+    test_build_stub_berth()
+    test_build_stub_user()
+    test_build_stub_ship()
+    test_build_stub_tug()
+    test_build_stub_shipcall()
+    test_build_stub_times()
+    test_build_stub_notification()
diff --git a/src/lib_brecal_utils/tests/test_import_modules.py b/src/lib_brecal_utils/tests/test_import_modules.py
new file mode 100644
index 0000000..cdbb942
--- /dev/null
+++ b/src/lib_brecal_utils/tests/test_import_modules.py
@@ -0,0 +1,102 @@
+import pytest
+
+def test_import_colorama():
+    """
+    colorama is used for 'pretty print' options, such as colored printing. For example, this is used in pytest-cov to quickly
+    highlight passing and failing tests
+    """
+    import colorama
+    return
+
+def test_import_matplotlib():
+    """matplotlib is used for visualizations (e.g. images and graphs)"""
+    import matplotlib
+    return
+
+def test_import_matplotlib_pyplot():
+    """pyplot as a sub-library of matplotlib, which is used to plot images and graphs"""
+    import matplotlib.pyplot as plt
+    return
+
+def test_import_tqdm_tqdm():
+    """tqdm is a neat utility library for simple display of progress in loops"""
+    from tqdm import tqdm
+    return
+
+def test_import_pandas():
+    """pandas is useful to handle dataframes and read from .csv or .json files, which can be collected into joint DataFrame objects"""
+    import pandas as pd
+    return
+
+def test_import_flask():
+    """flask is a WSGI framework for quick and easy design of web-based applications"""
+    import flask
+    from flask import Flask,  Blueprint, request
+    return
+
+def test_import_flask_specific_objects():
+    """common flask objects, such as the Flask api object, the Blueprint and requests"""
+    from flask import Flask,  Blueprint, request
+    return
+
+
+
+def test_import_mysql_connector():
+    """the 'mysql.connector' Object is used for the BreCal server database"""
+    import mysql.connector
+    return
+
+def test_import_pydapper():
+    """is a library that provides convenient methods for database related work"""
+    import pydapper
+    return
+
+def test_import_webargs():
+    """currently used in ~/brecal/src/server/BreCal/api/berths.py"""
+    import webargs
+    from webargs.flaskparser import parser
+    return
+
+def test_import_mashmallow():
+    """currently used in ~/brecal/src/server/BreCal/api/shipcalls.py"""
+    import marshmallow
+    from marshmallow import Schema, fields
+    return
+
+def test_import_flask_jwt_extended():
+    """currently used in ~/brecal/src/server/BreCal/api/login.py"""
+    import flask_jwt_extended
+    from flask_jwt_extended import create_access_token
+    return
+
+def test_import_pyjwt():
+    """currently used in ~/brecal/src/server/BreCal/services/jwt_handler.py"""
+    import jwt
+    return
+
+def test_import_bcrypt():
+    """currently used in ~/brecal/src/server/BreCal/impl/login.py"""
+    import bcrypt
+    return
+
+def test_import_math():
+    """math.isclose can be interesting to measure differences between two times (e.g., to ignore milliseconds)"""
+    import math
+    math.isclose
+    return
+
+def test_import_datetime():
+    """datetime is the default library for times"""
+    import datetime
+    datetime.datetime.now()
+    return
+
+
+if __name__=="__main__":
+    test_import_colorama()
+    test_import_matplotlib()
+    test_import_matplotlib_pyplot()
+    test_import_tqdm_tqdm()
+    test_import_pandas()
+    test_import_flask()
+
diff --git a/src/lib_brecal_utils/tests/test_test_handling.py b/src/lib_brecal_utils/tests/test_test_handling.py
new file mode 100644
index 0000000..877766e
--- /dev/null
+++ b/src/lib_brecal_utils/tests/test_test_handling.py
@@ -0,0 +1,48 @@
+import unittest
+import pytest
+
+def test_execute_coverage_test():
+    """
+    executes {execute_coverage_test} to check, whether reporting works as expected
+    """
+    import os
+    import brecal_utils
+
+    from brecal_utils.file_handling import get_project_root
+    from brecal_utils.test_handling import execute_coverage_test
+
+    root_dir = brecal_utils.__file__
+    root_dir = get_project_root("lib_brecal_utils", root_dir=root_dir)
+
+    tests_path = os.path.join(root_dir, "tests")
+    coverage_path = os.path.join(root_dir, "brecal_utils")
+    report_path = os.path.join(root_dir, "coverage_reports")
+
+    with pytest.raises(KeyboardInterrupt, match="is_test_interrupt"):
+        execute_coverage_test(tests_path=tests_path, coverage_path=coverage_path, cov_report_dst_dir=report_path, cov_fail_under_rate=0, is_test=1)
+    return
+
+def test_execute_coverage_test_no_report():
+    """
+    executes {execute_coverage_test} to check, whether the function also works without reporting
+    """
+    import os
+    import brecal_utils
+
+    from brecal_utils.file_handling import get_project_root
+    from brecal_utils.test_handling import execute_coverage_test
+
+    root_dir = brecal_utils.__file__
+    root_dir = get_project_root("lib_brecal_utils", root_dir=root_dir)
+
+    tests_path = os.path.join(root_dir, "tests")
+    coverage_path = os.path.join(root_dir, "brecal_utils")
+    report_path = os.path.join(root_dir, "coverage_reports")
+
+    with pytest.raises(KeyboardInterrupt, match="is_test_interrupt"):
+        execute_coverage_test(tests_path=tests_path, coverage_path=coverage_path, cov_report_dst_dir=None, cov_fail_under_rate=0, is_test=1)
+    return
+
+
+if __name__=="__main__":
+    pass
diff --git a/src/lib_brecal_utils/tests/test_time_handling.py b/src/lib_brecal_utils/tests/test_time_handling.py
new file mode 100644
index 0000000..70135d5
--- /dev/null
+++ b/src/lib_brecal_utils/tests/test_time_handling.py
@@ -0,0 +1,50 @@
+import pytest
+
+def test_difference_to_then_tgt_time_none():
+    import math
+    import datetime
+    from brecal_utils import difference_to_then
+
+    difference_in_seconds = 42
+    event_time = datetime.datetime.now() - datetime.timedelta(seconds=difference_in_seconds)
+    event_time_diff = difference_to_then(event_time) # tgt_time = datetime.datetime.now()
+
+    # {difference_to_then} internally creates a .now() time, when the {then_time} is not defined
+    # hence, the difference will never be exactly 42 seconds due to slight latency
+    # math.isclose allows deviations up to 0.05 seconds
+    assert math.isclose(42, event_time_diff, abs_tol=0.05), f"both times are reasonably close"
+    return
+
+def test_difference_to_then_tgt_time_not_none():
+    import math
+    import datetime
+    from brecal_utils import difference_to_then
+
+    difference_in_seconds = 42
+    event_time = datetime.datetime(2000, 1, 1, 0, 0, 0)
+    tgt_time = event_time - datetime.timedelta(seconds=difference_in_seconds)
+    event_time_diff = difference_to_then(event_time, tgt_time)
+
+    # tgt time is -42 seconds, as it is 42 seconds before event_time
+    assert event_time_diff==-42, f"event time difference is incorrect"
+    return
+
+def test_difference_to_then_tgt_time_not_none_make_absolute():
+    import math
+    import datetime
+    from brecal_utils import difference_to_then
+
+    difference_in_seconds = 42
+    event_time = datetime.datetime(2000, 1, 1, 0, 0, 0)
+    tgt_time = event_time - datetime.timedelta(seconds=difference_in_seconds)
+    event_time_diff = difference_to_then(event_time, tgt_time, make_absolute=True) # difference: -42. make_absolute: +42
+
+    # tgt time is -42 seconds, as it is 42 seconds before event_time. However, we are interested in an absolute value
+    assert event_time_diff==42, f"event time difference is incorrect"
+    return
+
+
+if __name__=="__main__":
+    test_difference_to_then()
+
+
diff --git a/src/lib_brecal_utils/tests/validators/__init__.py b/src/lib_brecal_utils/tests/validators/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib_brecal_utils/tests/validators/test_input_validation.py b/src/lib_brecal_utils/tests/validators/test_input_validation.py
new file mode 100644
index 0000000..a962470
--- /dev/null
+++ b/src/lib_brecal_utils/tests/validators/test_input_validation.py
@@ -0,0 +1,63 @@
+import pytest
+
+@pytest.fixture()
+def build_input_validation():
+    from brecal_utils.validators.input_validation import InputValidation
+    iv = InputValidation()
+    return locals()
+
+
+def test_build_input_validation():
+    from brecal_utils.validators.input_validation import InputValidation
+    iv = InputValidation()
+    return
+
+def test_all_models_are_supported(build_input_validation):
+    iv = build_input_validation["iv"]
+
+    from brecal_utils.stubs.ship import get_ship_simple
+    ship = get_ship_simple()
+    iv.assert_if_not_supported(ship)
+
+    from brecal_utils.stubs.shipcall import get_shipcall_simple
+    shipcall = get_shipcall_simple()
+    iv.assert_if_not_supported(shipcall)
+
+    from brecal_utils.stubs.berth import get_berth_simple
+    berth = get_berth_simple()
+    iv.assert_if_not_supported(berth)
+
+    from brecal_utils.stubs.participant import get_participant_simple
+    participant = get_participant_simple()
+    iv.assert_if_not_supported(participant)
+
+    from brecal_utils.stubs.user import get_user_simple
+    user = get_user_simple()
+    iv.assert_if_not_supported(user)
+
+    # placeholder: how to handle times?
+    return
+
+def test_ship_input_validation(build_input_validation):
+    iv = build_input_validation["iv"]
+
+    from brecal_utils.stubs.ship import get_ship_simple
+    ship = get_ship_simple()
+    violations, state = iv.verify(ship)
+    assert state, f"found violations: {violations}"
+    return
+
+def test_participant_input_validation(build_input_validation):
+    iv = build_input_validation["iv"]
+
+    from brecal_utils.stubs.participant import get_participant_simple
+    participant = get_participant_simple()
+    violations, state = iv.verify(participant)
+    assert state, f"found violations: {violations}"
+    return
+
+
+
+if __name__=="__main__":
+    pass
+
diff --git a/src/lib_brecal_utils/tests/validators/test_schema_validation_berth.py b/src/lib_brecal_utils/tests/validators/test_schema_validation_berth.py
new file mode 100644
index 0000000..900cfc6
--- /dev/null
+++ b/src/lib_brecal_utils/tests/validators/test_schema_validation_berth.py
@@ -0,0 +1,14 @@
+import pytest
+from brecal_utils.stubs.berth import get_berth_simple
+
+def test_berth():
+    with pytest.raises(ValueError, match="#TODO: copied from ships."):
+        berth = get_berth_simple()
+        
+        raise ValueError("#TODO: copied from ships.")
+        from brecal_utils.validators.schema_validation import test____
+        ship = get_ship_simple()
+        ship.length = 234
+        assert ship_length_in_range(ship)[0], f"ship length must be between 0 and 500 meters"
+    return
+
diff --git a/src/lib_brecal_utils/tests/validators/test_schema_validation_participant.py b/src/lib_brecal_utils/tests/validators/test_schema_validation_participant.py
new file mode 100644
index 0000000..9c51f60
--- /dev/null
+++ b/src/lib_brecal_utils/tests/validators/test_schema_validation_participant.py
@@ -0,0 +1,28 @@
+import pytest
+from brecal_utils.stubs.participant import get_participant_simple
+
+def test_participant_postal_code_len_is_five():
+    from brecal_utils.validators.schema_validation import participant_postal_code_len_is_five
+
+    participant = get_participant_simple()
+    assert participant_postal_code_len_is_five(participant)[0], f"the postal code should be exactly 5 numbers"
+    return
+
+def test_participant_postal_code_len_is_six_should_assert():
+    from brecal_utils.validators.schema_validation import participant_postal_code_len_is_five
+
+    participant = get_participant_simple()
+    participant.postal_code = "123456"
+    with pytest.raises(AssertionError, match="the postal code should be exactly 5 numbers"):
+        assert participant_postal_code_len_is_five(participant)[0], f"the postal code should be exactly 5 numbers"
+    return
+
+# TODO_postal_code_zero -> assert? Is postal_code mandatory?
+
+
+
+
+if __name__=="__main__":
+    test_participant_postal_code_len_is_five()
+    test_participant_postal_code_len_is_six_should_assert()
+
diff --git a/src/lib_brecal_utils/tests/validators/test_schema_validation_ship.py b/src/lib_brecal_utils/tests/validators/test_schema_validation_ship.py
new file mode 100644
index 0000000..71ddd19
--- /dev/null
+++ b/src/lib_brecal_utils/tests/validators/test_schema_validation_ship.py
@@ -0,0 +1,270 @@
+import pytest
+from brecal_utils.stubs.ship import get_ship_simple
+
+def test_ship_length_valid_range_234_is_valid():
+    from brecal_utils.validators.schema_validation import ship_length_in_range
+    ship = get_ship_simple()
+    ship.length = 234
+    assert ship_length_in_range(ship)[0], f"ship length must be between 0 and 500 meters"
+    return
+
+def test_ship_length_maximum_not_valid_range():
+    from brecal_utils.validators.schema_validation import ship_length_in_range
+    ship = get_ship_simple()
+    ship.length = 500
+    with pytest.raises(AssertionError):
+        assert ship_length_in_range(ship)[0], f"ship length must be between 0 and 500 meters, but is 500"
+    return
+
+def test_ship_length_minimum_not_valid_range():
+    from brecal_utils.validators.schema_validation import ship_length_in_range
+    ship = get_ship_simple()
+    ship.length = 0
+    with pytest.raises(AssertionError):
+        assert ship_length_in_range(ship)[0], f"ship length must be between 0 and 500 meters, but is 0"
+    return
+
+def test_ship_width_valid_range_137_is_valid():
+    from brecal_utils.validators.schema_validation import ship_width_in_range
+    ship = get_ship_simple()
+    ship.width = 137
+    assert ship_width_in_range(ship)[0], f"ship width must be between 0 and 500 meters"
+    return
+
+def test_ship_width_maximum_not_valid_range():
+    from brecal_utils.validators.schema_validation import ship_width_in_range
+    ship = get_ship_simple()
+    ship.width = 500
+    with pytest.raises(AssertionError):
+        assert ship_width_in_range(ship)[0], f"ship width must be between 0 and 500 meters, but is 500"
+    return
+
+def test_ship_width_minimum_not_valid_range():
+    from brecal_utils.validators.schema_validation import ship_width_in_range
+    ship = get_ship_simple()
+    ship.width = 0
+    with pytest.raises(AssertionError):
+        assert ship_width_in_range(ship)[0], f"ship width must be between 0 and 500 meters, but is 0"
+    return
+
+# not tug: values can be None and raise no error
+def test_ship_bollard_pull_is_none_and_not_tug():
+    from brecal_utils.validators.schema_validation import ship_bollard_pull_is_none_or_in_range
+    ship = get_ship_simple()
+    ship.is_tug = False
+    ship.bollard_pull = None
+    assert ship_bollard_pull_is_none_or_in_range(ship)[0], f"the bollard_pull should either be undefined or between 0 and 500 meters"
+    return
+
+def test_ship_participant_id_is_none_and_not_tug():
+    from brecal_utils.validators.schema_validation import ship_participant_id_is_none_or_int
+    ship = get_ship_simple()
+    ship.is_tug = False
+    ship.participant_id = None
+    assert ship_participant_id_is_none_or_int(ship)[0], f"the participant_id should either be undefined or an integer id"
+    return
+
+def test_ship_max_draft_is_none_and_not_tug():
+    from brecal_utils.validators.schema_validation import ship_max_draft_is_none_or_in_range
+    ship = get_ship_simple()
+    ship.is_tug = False
+    ship.max_draft = None
+    assert ship_max_draft_is_none_or_in_range(ship)[0], f"the max_draft should either be undefined or between 0 and 20 meters"
+    return
+
+
+# tug: values must be set, and are set. all tests should be accepted without assertion
+def test_ship_is_tug_bollard_pull_is_not_none():
+    from brecal_utils.validators.schema_validation import ship_bollard_pull_is_none_or_in_range
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.bollard_pull = 311
+    assert ship_bollard_pull_is_none_or_in_range(ship)[0], f"the bollard_pull should either be undefined or between 0 and 500 meters"
+    return
+
+
+def test_ship_is_tug_max_draft_is_not_none():
+    from brecal_utils.validators.schema_validation import ship_max_draft_is_none_or_in_range
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.max_draft = 17
+    assert ship_max_draft_is_none_or_in_range(ship)[0], f"the max_draft should either be undefined or between 0 and 20 meters"
+    return
+
+def test_ship_is_tug_participant_id_is_not_none():
+    from brecal_utils.validators.schema_validation import ship_participant_id_is_none_or_int
+    from brecal_utils.stubs import generate_uuid1_int
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.participant_id = generate_uuid1_int()
+    assert ship_participant_id_is_none_or_int(ship)[0], f"the participant_id should either be undefined or an integer id"
+    return
+
+def test_ship_is_tug_participant_id_is_str_and_fails():
+    from brecal_utils.validators.schema_validation import ship_participant_id_is_none_or_int
+    # note: this is an artificial test case. However, it ensures that operators using the backend cannot create an id incorrectly
+    from brecal_utils.stubs import generate_uuid1_int
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.participant_id = str(generate_uuid1_int())
+    with pytest.raises(AssertionError):
+        assert ship_participant_id_is_none_or_int(ship)[0], f"the participant_id should either be None or int, but is str"
+    return
+
+
+# tug: values must be set, but are not. all tests should raise AssertionError
+def test_ship_is_tug_bollard_pull_but_is_none_fails():
+    from brecal_utils.validators.schema_validation import ship_bollard_pull_is_defined_or_is_not_tug
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.bollard_pull = None
+    with pytest.raises(AssertionError):
+        assert ship_bollard_pull_is_defined_or_is_not_tug(ship)[0], f"the bollard_pull cannot be None, if the ship is a tug"
+    return
+
+def test_ship_is_tug_max_draft_but_is_none_fails():
+    from brecal_utils.validators.schema_validation import ship_max_draft_is_defined_or_is_not_tug
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.max_draft = None
+    with pytest.raises(AssertionError):
+        assert ship_max_draft_is_defined_or_is_not_tug(ship)[0], f"the max_draft cannot be None, if the ship is a tug"
+    return
+
+def test_ship_is_tug_participant_id_but_is_none_fails():
+    from brecal_utils.validators.schema_validation import ship_participant_id_is_defined_or_is_not_tug
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.participant_id = None
+    with pytest.raises(AssertionError):
+        assert ship_participant_id_is_defined_or_is_not_tug(ship)[0], f"the participant_id cannot be None, if the ship is a tug"
+    return
+
+
+# tug: values must be in valid range
+# # sequence: 1.) is valid, 2.) is too small, 3.) is too large
+def test_ship_is_tug_bollard_pull_in_range_311_valid():
+    from brecal_utils.validators.schema_validation import ship_bollard_pull_is_none_or_in_range
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.bollard_pull = 311
+    assert ship_bollard_pull_is_none_or_in_range(ship)[0], f"the bollard_pull must be 0<value<500"
+    return
+
+def test_ship_is_tug_bollard_pull_in_range_minimum_not_valid():
+    from brecal_utils.validators.schema_validation import ship_bollard_pull_is_none_or_in_range
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.bollard_pull = 0
+    with pytest.raises(AssertionError):
+        assert ship_bollard_pull_is_none_or_in_range(ship)[0], f"the bollard_pull must be 0<value<500, but is 0"
+    return
+
+def test_ship_is_tug_bollard_pull_in_range_maximum_not_valid():
+    from brecal_utils.validators.schema_validation import ship_bollard_pull_is_none_or_in_range
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.bollard_pull = 500
+    with pytest.raises(AssertionError):
+        assert ship_bollard_pull_is_none_or_in_range(ship)[0], f"the bollard_pull must be 0<value<500, but is 500"
+    return
+
+def test_ship_is_tug_max_draft_in_range_11_valid():
+    from brecal_utils.validators.schema_validation import ship_max_draft_is_none_or_in_range
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.max_draft = 11
+    assert ship_max_draft_is_none_or_in_range(ship)[0], f"the max_draft must be 0<value<20"
+    return
+
+def test_ship_is_tug_max_draft_in_range_minimum_not_valid():
+    from brecal_utils.validators.schema_validation import ship_max_draft_is_none_or_in_range
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.max_draft = 0
+    with pytest.raises(AssertionError):
+        assert ship_max_draft_is_none_or_in_range(ship)[0], f"the max_draft must be 0<value<20, but is 0"
+    return
+
+def test_ship_is_tug_max_draft_in_range_maximum_not_valid():
+    from brecal_utils.validators.schema_validation import ship_max_draft_is_none_or_in_range
+    ship = get_ship_simple()
+    ship.is_tug = True
+    ship.max_draft = 20
+    with pytest.raises(AssertionError):
+        assert ship_max_draft_is_none_or_in_range(ship)[0], f"the max_draft must be 0<value<20, but is 20"
+    return
+
+# Length tests
+
+def test_ship_eni_len_is_eight_and_passes():
+    from brecal_utils.validators.schema_validation import ship_eni_len_is_eight
+    ship = get_ship_simple()
+    ship.eni = "01234567" # 8 character example
+    assert ship_eni_len_is_eight(ship)[0], f"the eni-no. should have exactly 8 characters"
+    return
+
+def test_ship_eni_len_is_eight_but_has_nine():
+    from brecal_utils.validators.schema_validation import ship_eni_len_is_eight
+    ship = get_ship_simple()
+    ship.eni = "012345678" # 9 character example
+    with pytest.raises(AssertionError):
+        assert ship_eni_len_is_eight(ship)[0], f"the eni-no. should have exactly 8 characters, but has 9 characters"
+    return
+
+def test_ship_callsign_len_is_seven_at_maximum_seven_passes():
+    from brecal_utils.validators.schema_validation import ship_callsign_len_is_seven_at_maximum
+    ship = get_ship_simple()
+    ship.callsign = "0123456" # 7 character example
+    assert ship_callsign_len_is_seven_at_maximum(ship)[0], f"the callsign no. should have at maximum 7 characters"
+    return
+
+def test_ship_callsign_len_is_seven_at_maximum_six_passes():
+    from brecal_utils.validators.schema_validation import ship_callsign_len_is_seven_at_maximum
+    ship = get_ship_simple()
+    ship.callsign = "012345" # 6 character example
+    assert ship_callsign_len_is_seven_at_maximum(ship)[0], f"the callsign no. should have at maximum 7 characters"
+    return
+
+def test_ship_callsign_len_is_seven_at_maximum_eight_fails():
+    from brecal_utils.validators.schema_validation import ship_callsign_len_is_seven_at_maximum
+    ship = get_ship_simple()
+    ship.callsign = "01234567" # 8 character example
+
+    with pytest.raises(AssertionError):
+        assert ship_callsign_len_is_seven_at_maximum(ship)[0], f"the callsign no. should have at maximum 7 characters, but has 8"
+    return
+
+def test_ship_callsign_len_is_seven_at_maximum_zero_passes():
+    from brecal_utils.validators.schema_validation import ship_callsign_len_is_seven_at_maximum
+    ship = get_ship_simple()
+    ship.callsign = "" # 0 character example
+    assert ship_callsign_len_is_seven_at_maximum(ship)[0], f"the callsign no. should have at maximum 7 characters"
+    return
+
+def test_imo_len_is_seven_and_seven_passes():
+    from brecal_utils.validators.schema_validation import ship_imo_len_is_seven
+    ship = get_ship_simple()
+    ship.imo = 1234567 # integer required
+    assert ship_imo_len_is_seven(ship)[0], f"a ship's IMO no. should have exactly 7 characters"
+    return
+
+def test_imo_len_is_seven_and_eight_fails():
+    from brecal_utils.validators.schema_validation import ship_imo_len_is_seven
+    ship = get_ship_simple()
+    ship.imo = 12345678 # integer required
+    with pytest.raises(AssertionError):
+        assert ship_imo_len_is_seven(ship)[0], f"a ship's IMO no. should have exactly 7 characters, but it has 8 character"
+    return
+
+def test_imo_len_is_seven_and_one_fails():
+    from brecal_utils.validators.schema_validation import ship_imo_len_is_seven
+    ship = get_ship_simple()
+    ship.imo = 1 # integer required
+    with pytest.raises(AssertionError):
+        assert ship_imo_len_is_seven(ship)[0], f"a ship's IMO no. should have exactly 7 characters, but is has 1 character"
+    return
+
+
+if __name__=="__main__":
+    pass
diff --git a/src/lib_brecal_utils/tests/validators/test_validation_rule_functions.py b/src/lib_brecal_utils/tests/validators/test_validation_rule_functions.py
new file mode 100644
index 0000000..498dd43
--- /dev/null
+++ b/src/lib_brecal_utils/tests/validators/test_validation_rule_functions.py
@@ -0,0 +1,159 @@
+import pytest
+from brecal_utils.validators.validation_rule_functions import ValidationRuleFunctions
+from brecal_utils.validators.validation_rules import ValidationRules
+from brecal_utils.database.sql_handler import SQLHandler
+
+@pytest.fixture(scope="session")
+def build_sql_proxy_connection():
+    import mysql.connector
+    conn_from_pool = mysql.connector.connect(**{'host':'localhost', 'port':3306, 'user':'root', 'password':'HalloWach_2323XXL!!', 'pool_name':'brecal_pool', 'pool_size':20, 'database':'bremen_calling', 'autocommit': True})
+    sql_handler = SQLHandler(sql_connection=conn_from_pool, read_all=True)
+    vr = ValidationRules(sql_handler)
+    return locals()
+
+def test_build_validation_rule_functions(build_sql_proxy_connection):
+    import types
+    sql_handler = build_sql_proxy_connection["sql_handler"]
+    vr = build_sql_proxy_connection["vr"]
+
+    validation_rule_functions = vr.get_validation_rule_functions()
+    assert isinstance(validation_rule_functions, list), f"must return a list of methods"
+    for vrule in validation_rule_functions:
+        assert isinstance(vrule,types.MethodType), f"every element returned from get_validation_rule_functions must be a method. found: {type(vrule)}"
+    assert len(validation_rule_functions)>0, f"must return at least one method!"
+    return
+
+
+
+
+def test_validation_rule_fct_agency_and_terminal_pier_side_disagreement(build_sql_proxy_connection):
+    """#0006-A validation_rule_fct_agency_and_terminal_pier_side_disagreement"""
+    import pandas as pd
+
+    from brecal_utils.stubs.times_full import get_times_full_simple
+    from brecal_utils.stubs.shipcall import get_shipcall_simple
+    from brecal_utils.database.enums import ParticipantType
+    from brecal_utils.database.enums import StatusFlags
+
+    vr = build_sql_proxy_connection["vr"]
+    shipcall = get_shipcall_simple()
+    t1 = get_times_full_simple()
+    t2 = get_times_full_simple()
+
+    # roles: agency & terminal
+    t1.participant_type = ParticipantType.AGENCY.value
+    t2.participant_type = ParticipantType.TERMINAL.value
+
+    # disagreement
+    t1.pier_side = True
+    t2.pier_side = False
+
+    time_objects = [t1, t2]
+    df_times = pd.DataFrame.from_records([to_.__dict__ for to_ in time_objects])
+    df_times.set_index('id',inplace=True)
+
+    (state, description) = vr.validation_rule_fct_agency_and_terminal_pier_side_disagreement(shipcall, df_times)
+    assert state.value > StatusFlags.GREEN.value, f"a violation must be identified"
+    assert description is not None, f"a violation description must be identified"
+    return
+
+
+def test_validation_rule_fct_agency_and_terminal_pier_side_agreement(build_sql_proxy_connection):
+    """#0006-A validation_rule_fct_agency_and_terminal_pier_side_disagreement"""
+    import pandas as pd
+
+    from brecal_utils.stubs.times_full import get_times_full_simple
+    from brecal_utils.stubs.shipcall import get_shipcall_simple
+    from brecal_utils.database.enums import ParticipantType
+    from brecal_utils.database.enums import StatusFlags
+
+    vr = build_sql_proxy_connection["vr"]
+    shipcall = get_shipcall_simple()
+    t1 = get_times_full_simple()
+    t2 = get_times_full_simple()
+
+    # roles: agency & terminal
+    t1.participant_type = ParticipantType.AGENCY.value
+    t2.participant_type = ParticipantType.TERMINAL.value
+
+    # agreement
+    t1.pier_side = True
+    t2.pier_side = True
+
+    time_objects = [t1, t2]
+    df_times = pd.DataFrame.from_records([to_.__dict__ for to_ in time_objects])
+    df_times.set_index('id',inplace=True)
+
+    (state, description) = vr.validation_rule_fct_agency_and_terminal_pier_side_disagreement(shipcall, df_times)
+    assert state.value == StatusFlags.GREEN.value, f"no violation should be observed"
+    assert description is None, f"no violation should be observed"
+    return
+
+
+
+
+def test_validation_rule_fct_agency_and_terminal_berth_id_disagreement(build_sql_proxy_connection):
+    """#0006-B validation_rule_fct_agency_and_terminal_pier_side_disagreement"""
+    import pandas as pd
+
+    from brecal_utils.stubs.times_full import get_times_full_simple
+    from brecal_utils.stubs.shipcall import get_shipcall_simple
+    from brecal_utils.database.enums import ParticipantType
+    from brecal_utils.database.enums import StatusFlags
+
+    vr = build_sql_proxy_connection["vr"]
+    shipcall = get_shipcall_simple()
+    t1 = get_times_full_simple()
+    t2 = get_times_full_simple()
+
+    # roles: agency & terminal
+    t1.participant_type = ParticipantType.AGENCY.value
+    t2.participant_type = ParticipantType.TERMINAL.value
+
+    # disagreement
+    t1.berth_id = 1
+    t2.berth_id = 2
+
+    time_objects = [t1, t2]
+    df_times = pd.DataFrame.from_records([to_.__dict__ for to_ in time_objects])
+    df_times.set_index('id',inplace=True)
+
+    (state, description) = vr.validation_rule_fct_agency_and_terminal_berth_id_disagreement(shipcall, df_times)
+    assert state.value > StatusFlags.GREEN.value, f"a violation must be identified"
+    assert description is not None, f"a violation description must be identified"
+    return
+
+def test_validation_rule_fct_agency_and_terminal_berth_id_agreement(build_sql_proxy_connection):
+    """#0006-B validation_rule_fct_agency_and_terminal_pier_side_disagreement"""
+    import pandas as pd
+
+    from brecal_utils.stubs.times_full import get_times_full_simple
+    from brecal_utils.stubs.shipcall import get_shipcall_simple
+    from brecal_utils.database.enums import ParticipantType
+    from brecal_utils.database.enums import StatusFlags
+
+    vr = build_sql_proxy_connection["vr"]
+    shipcall = get_shipcall_simple()
+    t1 = get_times_full_simple()
+    t2 = get_times_full_simple()
+
+    # roles: agency & terminal
+    t1.participant_type = ParticipantType.AGENCY.value
+    t2.participant_type = ParticipantType.TERMINAL.value
+
+    # agreement
+    t1.berth_id = 21
+    t2.berth_id = 21
+
+    time_objects = [t1, t2]
+    df_times = pd.DataFrame.from_records([to_.__dict__ for to_ in time_objects])
+    df_times.set_index('id',inplace=True)
+
+    (state, description) = vr.validation_rule_fct_agency_and_terminal_berth_id_disagreement(shipcall, df_times)
+    assert state.value == StatusFlags.GREEN.value, f"no violation should be observed"
+    assert description is None, f"no violation should be observed"
+    return
+
+
+
+
diff --git a/src/lib_brecal_utils/tests/validators/test_validation_rule_state.py b/src/lib_brecal_utils/tests/validators/test_validation_rule_state.py
new file mode 100644
index 0000000..3ea2281
--- /dev/null
+++ b/src/lib_brecal_utils/tests/validators/test_validation_rule_state.py
@@ -0,0 +1,26 @@
+import pytest
+from brecal_utils.database.enums import StatusFlags
+
+def test_validation_rule_state_green_is_1():
+    assert StatusFlags.GREEN.value==1
+    return
+
+def test_validation_rule_state_yellow_is_2():
+    assert StatusFlags.YELLOW.value==2
+    return
+
+def test_validation_rule_state_red_is_3():
+    assert StatusFlags.RED.value==3
+    return
+
+def test_validation_rule_state_order():
+    # Red 3, Yellow 2, Green 1, None 0
+    # red>yellow>green>none
+    assert StatusFlags.RED.value>StatusFlags.YELLOW.value
+    assert StatusFlags.YELLOW.value>StatusFlags.GREEN.value
+    assert StatusFlags.GREEN.value>StatusFlags.NONE.value
+    return
+
+if __name__=="__main__":
+    pass
+
diff --git a/src/server/requirements.txt b/src/server/requirements.txt
index ca817e1..9c7b54f 100644
--- a/src/server/requirements.txt
+++ b/src/server/requirements.txt
@@ -10,4 +10,9 @@ pydapper[mysql-connector-python]
 marshmallow-dataclass
 bcrypt
 jwt
-flask-jwt-extended
\ No newline at end of file
+flask-jwt-extended
+SQLAlchemy
+numpy
+pandas
+
+
diff --git a/src/server/tests/__init__.py b/src/server/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/server/tests/api/__init__.py b/src/server/tests/api/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/server/tests/impl/__init__.py b/src/server/tests/impl/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/server/tests/schemas/__init__.py b/src/server/tests/schemas/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/server/tests/services/__init__.py b/src/server/tests/services/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/server/tests/test_create_app.py b/src/server/tests/test_create_app.py
new file mode 100644
index 0000000..c119bfe
--- /dev/null
+++ b/src/server/tests/test_create_app.py
@@ -0,0 +1,21 @@
+import pytest
+
+def test_create_app():
+    """
+    
+    """
+    import os
+    import sys
+    from brecal_utils import get_project_root
+
+    project_root = get_project_root("brecal")
+    lib_location = os.path.join(project_root, "src", "server")
+    sys.path.append(lib_location)
+
+    from BreCal import create_app
+    os.chdir(project_root) # set the current directory to ~/brecal, so the config is found
+    application = create_app()
+    return
+
+if __name__=="__main__":
+    test_create_app()