Skip to content

exercise-5.md

Latest commit

 

History

History
108 lines (75 loc) · 6.41 KB

exercise-5.md

File metadata and controls

108 lines (75 loc) · 6.41 KB
Raw

Prerequisites • Exercise 0 • Exercise 1 • Exercise 1.1 • Exercise 2 • Exercise 3 • Exercise 4 • Exercise 5 • Exercise 6 • Exercise 7

Exercise 5 - Exclusive Gateways

In this exercise you will add a decision point to the exampleorg_dicProcess: based on the value of the tutorial-input parameter sent with the start Task, the process will either trigger exampleorg_cosProcess or stop right there.

The file you will primarily work in is dic-process.bpmn and DicTask.java.

Solutions to this exercise are found on the branch solutions/exercise-5.

Background reading (documentation links for this exercise)

Exercise Tasks

  1. Open tutorial-process/src/main/resources/bpe/dic-process.bpmn in Camunda Modeler and add an Exclusive Gateway between the DicTask service task and the current end/message-end event.

    Connect two outgoing sequence flows from the gateway:

    • Path A: leads to the Message End Event that sends helloCos (from Exercise 4) → starts exampleorg_cosProcess
    • Path B: leads to a plain End Event → stops exampleorg_dicProcess without contacting COS
    Camunda Modeler instructions
    • Click the DicTask service task → select Append Gateway
    • Draw a sequence flow from the gateway to the existing Message End Event (Path A)
    • Draw another sequence flow from the gateway to a new plain End Event (Path B)

  2. Add a condition expression to each outgoing sequence flow so the BPE knows which path to take at runtime.

    The BPE uses JUEL (Java Unified Expression Language) for conditions. Condition expressions read process variables by name. For a boolean variable called sendToCos, the expressions would be:

    Sequence flow Condition expression Meaning
    Path A (→ COS) ${sendToCos} Take this path when sendToCos is true
    Path B (→ End) ${!sendToCos} Take this path when sendToCos is false

    You can freely choose the variable name — just make sure it matches exactly between the condition expressions here and the process variable you set in step 4.

    Camunda Modeler instructions
    • Click a sequence flow arrow → in the properties panel on the right, find Condition Type → select Expression
    • Enter the expression (e.g. ${sendToCos}) in the Expression field

  3. In the DicTask class, read the tutorial-input string from the start Task and derive a boolean decision from it.

    What: Evaluate whether the input value signals that the COS process should be started.
    Why: The gateway condition reads a process variable — that variable must be set by your Java code before the gateway is reached. This is done in the next step.

    Not sure how to read the tutorial-input parameter?

    Use the TaskHelper together with variables as you did in Exercise 2. The input type code is tutorial-input from CodeSystem http://example.org/fhir/CodeSystem/tutorial. Once you have the string value, decide on a convention — for example, "true" means start COS, anything else means stop.

  4. Store the boolean result as a named process variable using variables.setBoolean(...). The variable name must be identical to the name used in the condition expressions in step 2.

Solution Verification

Maven Build and Automated Tests

Execute a maven build of the dsf-process-tutorial parent module via:

mvn clean install -Pexercise-5

Verify that the build was successful and no test failures occurred.

Process Execution and Manual Tests

To verify the exampleorg_dicProcess and exampleorg_cosProcesses can be executed successfully, we need to deploy them into DSF instances and execute the exampleorg_dicProcess. The maven install build is configured to create a process jar file with all necessary resources and copy the jar to the appropriate locations of the docker dev setup.

  1. Start the DSF FHIR server for the dic.dsf.test organization in a console at location .../dsf-process-tutorial/dev-setup:

    docker compose up dic-fhir

    Verify the DSF FHIR server started successfully at https://dic/fhir.

  2. Start the DSF BPE server for the dic.dsf.test organization in a second console at location .../dsf-process-tutorial/dev-setup:

    docker compose up dic-bpe

    Verify the DSF BPE server started successfully and deployed the exampleorg_dicProcess.

  3. Start the DSF FHIR server for the cos.dsf.test organization in a third at location .../dsf-process-tutorial/dev-setup:

    docker compose up cos-fhir

    Verify the DSF FHIR server started successfully at https://cos/fhir.

  4. Start the DSF BPE server for the cos.dsf.test organization in a fourth console at location .../dsf-process-tutorial/dev-setup:

    docker compose up cos-bpe

    Verify the DSF BPE server started successfully and deployed the exampleorg_cosProcess.

  5. Start the exampleorg_dicProcess by posting a specific FHIR Task resource to the DSF FHIR server of the dic.dsf.test organization using either cURL or the DSF FHIR server's web interface. Check out Starting A Process Via Task Resources again if you are unsure.

    Verify that the exampleorg_dicProcess was executed successfully by the dic.dsf.test DSF BPE server and possibly the exampleorg_cosProcess by the cos.dsf.test DSF BPE server, depending on whether decision of your algorithm based on the input parameter allowed starting the exampleorg_cosProcess.

Prerequisites • Exercise 0 • Exercise 1 • Exercise 1.1 • Exercise 2 • Exercise 3 • Exercise 4 • Exercise 5 • Exercise 6 • Exercise 7