..
    Licensed under the MIT License.
    For details on the licensing terms, see the LICENSE file.
    SPDX-License-Identifier: MIT

    Copyright 2023-2024 (c) Fraunhofer IOSB (Author: Florian Düwel)





============================
Service Specific Assignment
============================


The `Demonstration Scenario <https://github.com/swap-it/demo-scenario>`_ defines a structure SWAP_Order that must be handed over to each service to be executed.
For the Service Specific Assignment, a Device Registry is required, as well as an external assignment agent. The assignment agent will be locally registered in the execution engine for a single service,
so that it is considered only there. The remaining assignment steps are accomplished with the default assignment strategy of the execution engine.

To register the local assignment agent, an *AssignmentAgent* structure is defined in the PFDL for the *Gluing* service and is handed over to the execution engine as service input argument.


PFDL Definition
================


.. code-block:: python

    Struct SWAP_Order
        order_id:number
        stand:Stand_Segment
        segments: Light_Segment[]
        number_light_segments: number
    End

    Struct Stand_Segment
                stand_shape:string
                stand_height:number
                stand_id:string
    End

    Struct Light_Segment
                color: string
                diameter: number
                segment_id:string
    End

    Struct AssignmentAgent
            agent:string
    End

    Task productionTask
                manufacture_light_segments
                    In
                        SWAP_Order
                        {
                            "order_id":1000,
                            "stand":{
                                "stand_shape":"plate",
                                "stand_height":3,
                                "stand_id": "Default"
                            },
                            "segments":
                            [
                            {
                                "color": "red",
                                "diameter": 5,
                                "segment_id": "Default"
                            },
                            {
                                "color": "green",
                                "diameter": 5,
                                "segment_id": "Default"
                            }
                            ],
                            "number_light_segments": 5
                        }
    End

    Task manufacture_light_segments
                In
                    order: SWAP_Order
                Parallel Loop i To order.number_light_segments
                    manufacture_light_segment
                        In
                            order
                        Out
                            order:SWAP_Order
                Loop i To order.number_light_segments
                    Gluing
                        In
                            AssignmentAgent
                            {
                                "agent":"opc.tcp://localhost:10000"
                            }
                            order
                        Out
                            order:SWAP_Order
    End

    Task manufacture_light_segment
                In
                    order: SWAP_Order
                GetPartsFromWarehouse
                    In
                        order
                    Out
                        order: SWAP_Order
                Coating
                    In
                        order
                    Out
                        order: SWAP_Order
                Out
                    order
    End



Process Execution
=================
To execute the above-defined PFDL-process, a small `python script <https://github.com/FraunhoferIOSB/swap-it-execution-engine/blob/main/Tutorial/service_specific_assignment.py>`_
is required to set up the execution engine and the docker environment:

.. code-block:: python

    import time, os, sys
    #add directories to the system path
    sys.path.append(os.path.join(os.path.dirname(__file__), "../."))
    sys.path.append(os.path.join(os.path.dirname(__file__), "../tests/test_helpers/."))
    #import the main function
    from main import main
    #import the docker environment
    from util.start_docker_compose import DockerComposeEnvironment

    if __name__ == '__main__':
        #configure the required docker environment
        env = DockerComposeEnvironment(["Device_Registry", "Service_Server", "Dashboard", "Assignment_Agent"])
        #start the docker environment
        env.run_docker_compose("./Tutorial/docker-compose.yaml")
        #wait until the server started
        time.sleep(10)
        #run the execution engine
        main()
        #shut down the docker environment
        env.stop_docker_compose()


Here, we first need to add the root directory of the repository to the system path to import the main function of the execution engine. Beside, we can re-use the
docker-environment from the test section.

For this Tutorial, the terminal command must be extended with three of the optional arguments. First, a global Device Registry is set with the argument *"device_registry_url"="opc.tcp://localhost:8000"*. Besides,
each service server registers itself in the Device Registry with the URI from the docker compose environment, so that the URI returned from the
Device Registry must ab adjusted, to replace the docker-internal URI with a docker-external URI. Here, the optional argument *"custom_url"="opc.tcp://localhost:"* is added, so that each server from the
docker-environment can be reached from outside. In addition to that,
we will set another argument, to increase the number of default clients for the execution engine's control interface. Here, the argument *"number_default_clients"=5* is provided, so that the execution
engine starts with a set of 5 control interface clients. The assignment agent argument *"assignment_agent_url"="opc.tcp://localhost:10000"* is not provided, since the assignment should be accomplished with the default behavior. However,
it is also possible to define a global assignment agent, which can be locally replaced for single services


The process can then be executed from the command line with:

.. code-block:: python

    python Tutorial/service_specific_assignment.py "opc.tcp://localhost:4840" "Tutorial/PFDL/service_specific_assignment.pfdl" "dashboard_host_address"="http://localhost:8080" "device_registry_url"="opc.tcp://localhost:8000" "custom_url"="opc.tcp://localhost:" "number_default_clients"=5

so that we can execute the process and map it on the `SWAP-IT Dashboard <https://github.com/iml130/swap-it-dashboard>`_. In case that the log messages of the execution
engine should be captured, the command line argument can be simply adjusted to:

.. code-block:: python

    python Tutorial/service_specific_assignment.py "opc.tcp://localhost:4840" "Tutorial/PFDL/service_specific_assignment.pfdl" "dashboard_host_address"="http://localhost:8080" "log_info"=True "device_registry_url"="opc.tcp://localhost:8000" "custom_url"="opc.tcp://localhost:"