VWS4LS Order Driven Production

The bidding process demonstrator was developed in the research project Asset Administration Shell for the Wiring Harness (VWS4LS). which was funded by the German Federal Ministry of Education and Research. A detailed description of the results of the various subprojects can be found here (German only).

The demonstrator shows an order driven production with the help of proactive Asset Administration Shells (AAS) and Business Pocess Model Notation (BPMN).

The architecture of the demonstrator is shown in Fig. 1. On the left side you can see the abstract architeture¹ of a proactive AAS with a passive and an active part. The right side shows the technical implementation. The exchange of I4.0-messages between several AAS is realized by an AAS submodel called Message Participant. In this submodel an operation with the name newMessage is implemented which follows the message structure of VDI 2193²,³. To start the bidding process an additional user defined operation is specified in the Service Requester's AAS. Further details can be found in the published paper on the bidding process⁴.

Fig. 1: Architecture of proactive AAS

According to the architecture on the right in Fig. 1, the demonstrator consists of the following software components:

Blue coloured: Basyx components AAS-Registry, AAS-Repository and the AAS-GUI. Orange coloured: Flowable-UI White coloured: Node-Red server Green coloured: Single flows implemented in Node-Red server

To set up and run the demonstrator, two options exist.

• Option 1: Run the demonstrator with existing program code.
• Option 2: Expand the code of the demonstrator

Option 2 can be implemented after the instructions of option 1 have been executed.

Option 1: Run the demonstrator with existing programm code

Set up environment

Docker

A Docker Engine should be installed on your computer.

Download the Flowable Docker image:

docker pull ghcr.io/vws4ls/vws4ls-bidding-process/deploy-flowable:latest

Node-Red

The bidding process contains an algorithm to determine the feasible scope of the Service Provider. For this the capability matching algorithm is needed which uses own developed nodes in Node-Red. To set up the Node-Red environment follow the steps in the capability matching repository.

Run the demonstrator

Download program code

Clone or download the zip file with the program code.

Switch to the folder deploy in your local folder.

Change the the variable basyx.externalurl in the file application.properties to the IP adress of your computer. The port can be left as it is.

Start a command line in the deploy folder and type the following command:

docker compose up -d

If all docker containers are started correctly you can reach the single software applications under the following adresses:

Basyx-UI: http://localhost:3000/ Node-Red: http://localhost:1880/ Flowable: http://localhost:8081/flowable-ui/

The default credentials for Flowable are as follows:

Name: admin
Password: test

Hint: The credentials are used in the http-request invoked by the Node-Red server. If the credentials will be changed than this reuquest-nodes needs to be changed accordingly.

Initialize Flowable and Node-Red

When the containers are started for the first time, Node-Red and Flowable must be initialized. For this go to the directory deploy/config and do the following steps.

Import Node-Red flows Import the four flows from the directory deploy/config/node-red into your Node-Red server.

Import Flowable apps Go to the Apps tab in Flowable and import the two zip folders from the directory deploy/config/flowable into Flowable (see Fig. 2).

Fig. 2: Import of Flowable Apps

Then publish the apps. Therfore, click on one app, for example the Service Requester, and click on Publish (see Fig. 3). Do the same for the Service Provider. After the import process, the associated Processes and Forms can be seen in the tabs of the same name (see Fig. 4 and Fig. 5).

Fig. 3: Publish of Flowable Apps

Fig. 4: Processes in Flowable

Fig. 5: Forms in Flowable

The same process is shown in the video which is stored in the directory videos/Init_FlowableApps.mp4.

Start a bidding process

To start a bidding process at least one Service Requester AAS and Service Provider AAS, which need to implement the Message Participant Submodel, must be stored in the AAS-Repository. For this example AAS are stored in the directoy deploy/aasx.

The following video shows how the software applications work together. Therfore one selection strategy is implemented that selects the best proposal regarding the process duration. To have a more automated bidding process and a very manual bidding process the strategy could be called in two kinds. The first kind is called "timeManual" and shows the whole bidding process with all user tasks which are implemented in the business process models. The second kind is called "time" and skips some of the user tasks.

Both kinds are shown in the video which is stored in the directory videos/Example_Process.mp4.

Option 2: Expand the code of the

The demonstrator was developed for a special use case. If you want to change something you have to change the code of the Flowable delegates. To do so, you have to follow the instructions of option 2.

Detailed information of implementing delegates in Flowable can be found here.

Build and start

Build jar files

A dedicated development container is used for this, defined by the docker-compose.yml file in the main directory of the bidding process.

Start a command line in the main directory and type the following commands to build all necessary jar files:

docker compose build
docker compose run sdk
cd /src/FlowableDelegates
mvn package

This will generate jar files in the corresponding target folders, like target/FlowableDelegates-1.0-SNAPSHOT.jar.

Build containers

Next, the docker images of the deploy folder need to be build. These use the previously generated jar files, which need to be copied:

Type in the opend command line following commands:

cd deploy
./build.sh

Start demonstrator

Finally, the containers can be started:

cd deploy
docker compose up -d

Then make the same steps as described in the section Start a bidding process

Footnotes

1. A. Belyaev und C. Diedrich, “Specification Demonstrator I4.0-Language v3.0,” Otto-von-Guericke-University Magdeburg, IFAT-LIA, Magdeburg, July 2019. ↩

2. VDI/VDE, “VDI/VDE 2193-1: Language for I4.0 components - Structure of messages,” April 2020 ↩

3. VDI/VDE, “VDI/VDE 2193-2: Language for I4.0 components - Interaction protocol for tendering procedures,” January 2020 ↩

4. ↩