Camunda Platform http connector usage example

This example illustrates the invocation of a REST service from a service task in Camunda BPM using the http connector. The example uses a Camunda Spring Boot deployment but should work in the same way on other deployments.

No Java code is required. If you are comfortable with some Java / Spring then the recommended approach is to use a Spring bean instead of the connector, as shown in the example rest-service-task-spring. Spring beans are more flexible, e.g. allow to add custom error handling, and are easier testable.

The service invoked by the example is hosted at reqres.in. Many thanks to Ben Howdle for providing this developer playground.

The project includes two example process models, one with a GET and one with a POST.

The GET example illustrates how to

configure the connector
add the value of a process variable to the url
read a specific field from the REST service's JSON response using Camunda Spin
print the email field extracted from the response to the console using a script on the end event
test the process from jUnit using Camunda BPM Assert

The POST example illustrates how to

configure the connector
add an authorization header fro http basic authentication if needed
add the value of a process variable to the message body (payload)
save the response
print the response to the console using a script on the end event
test the process from jUnit using Camunda BPM Assert

Also see related product documentation

The important parts

GET Example

On the service task set the implementation to "Connector". The set the connector properties (method, headers, url) on the appearing tab as shown. A response of type JSON can be read and navigated using JavaScript or an expression (shown).
BPMN Process

Connector configuration in CAMUNDA Modeler

The prepackaged distribution includes everything needed.

If you are starting form a Spring Boot project, you need to include the dependencies for connect, http-client, Spin and Json:

   <dependencies>
...
    <dependency>
            <groupId>org.camunda.bpm</groupId>
            <artifactId>camunda-engine-plugin-connect</artifactId>
        </dependency>
        <dependency>
            <groupId>org.camunda.connect</groupId>
            <artifactId>camunda-connect-http-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.camunda.bpm</groupId>
            <artifactId>camunda-engine-plugin-spin</artifactId>
        </dependency>
        <dependency>
            <groupId>org.camunda.spin</groupId>
            <artifactId>camunda-spin-dataformat-json-jackson</artifactId>
        </dependency>
...
    </dependencies>

POST Example

Set the method value to POST instead and create an input parameter named payload for the request body. Add a header field Authorization if needed. The value for this filed needs to be base 64 encoded and can be created for instance using these commands:

Powershell: [System.Convert]::ToBase64String([System.Text.Encoding]::UTF8.GetBytes($user+":"+$pass))

Linux: echo “username:password” | base64

Connector configuration for POST in CAMUNDA Modeler

Unit Test

Run the jUnit test in your IDE or using:

mvn clean test

Step through the process manually

You can start the server using your IDE or

mvn spring-boot:run

and step through the process manually. After the server has started you can access the Camunda tasklist via http://localhost:8080/app/tasklist. Use the credentials demo / demo to login.

Run and inspect with Tasklist and Cockpit

Use tasklist and cockpit as described in the product documentation for

License

Apache License, Version 2.0.

rob2universe/camunda-http-connector-example