As a Developer I want to apply and deploy basic Camunda DMN

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For the rule engine we'll use Camunda Platform 7.16 on Apache Tomcat 9.0.60.

For development we need:

• [ ] connection Camunda Platform
• [ ] open source Camunda Modeler
• [ ] create DMN model
• [ ] deploy DMN
• [ ] evaluate DMN via REST API

We illustrate the different steps in the comments in this issue.

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connection Camunda Platform

• Link to Apache Tomcat/9.0.60
• Link to Camunda App

Credentials for Camunda App are shared and available to SAP colleagues in the private SAP github. Please check the task complete if connectivity is successful.

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open source Camunda Modeler

Camunda Modeler can be run on Windows, MacOS, and Linux. The corresponding packages can be found on the downloads page.

After installation the application shows this screen. Please check the task complete if installation is successful.

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create DMN model

We make a very simple decision table to determine whether someone is legally old enough to be allowed to make a (sales) transaction as specified in #8

• Select DMN diagriam underneath Camunda Platform 7 in the opening window of Camunda Modeler
• Click on de small blue area left upper Decision 1
• Adjust diagram_1.dmn according to the example below. Make sure you change the Type to integer and boolean respectively. And don't forget to change the Input Variable to Age and the Output Name to LegalAge as well.
• Save File. Please check the task complete if successful.

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deploy DMN

• Click the rocket symbol at the bottom of the gray bar and fill in the required fields (you can skip the Tenant ID). For your convenience, you can copy the REST enpoint here: https://vil-regels.nl:8443/engine-rest
• Hit the Deploy button
• You should see.
• Finally you can check this in the Camunda Cockpit itself.
• Details will show like this. Please check the task complete if deployment is successful.

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evaluate DMN via REST API

We will illustrate this with the POST /decision-definition/key/{key}/evaluate API call via Postman. Detailed REST API refernce can be found here

The {key} four our test can be found in the Camunda Cockpit details page of the deployed DMN. Here, this is Decision_17h4e0q. That might be different with your deployed version of the DMN.

We're ready to configure Postman now:

• Type: POST
• Request url: https://vil-regels.nl:8443/engine-rest/decision-definition/key/Decision_17h4e0q/evaluate
• In the Authorization tab, select Basic Auth and provide the credentials
• In the body we specify the Age variable in JSON style { "variables" : { "Age" : { "value" : "14", "type" : "Integer" } } }
• Hitting the Send button will give you the response [ { "LegalAge": { "type": "Boolean", "value": false, "valueInfo": {} } } ]
• Every API call will be registered in the Camunda Cockpit. In this case I've sent four different requests (see the ID under Decision Instances).
• The top ID was the last call. Selecting it shows the row hitted.

This finalizes the basics of Camunda DMN. Please check the final task complete where applicable.