Springboot API

A next logical step to creating a Springboot based jBPM API is to create a simple Hello, World API.

• second-business-application-kjar: Holds a simple process flow that takes a “name” parameter and prepends a “Hello ” on to the front of it in a script task.
• second-business-application-service: Adds a simple RestController to start the process flow, pass a name parameter to it, read and return the result.

In order to manipulate a parameter in a business flow a process variable is added to the simple-process.bpmn2 business process created in the first-business-application-kjar project.

The simple-process.bpmn2 process is opened in the Eclipse BPMN2 modeler. The background of the process is clicked on (just to be sure) and the properties view is opened. The Data Items tab is opened selected and the plus + sign is clicked in the Properties List for Process Simple Process is clicked. A new process var is created with with the name processVar1 and of Data Type xs:string.

The Script Task 1 is clicked and the Script Task tab is opened. The script in the Script field is changed to

kcontext.setVariable("processVar1", "Hello " + kcontext.getVariable("processVar1"));

In short, kcontext is available to all business process scripts and allows access to the jBPM API from within a business flow. This new script reads the process variable processVar1 and prepends the string Hello and stores the result back into the process variable.

Build and install the new kjar into the local maven repository.

Building the service rest interface is just a matter of changing the Application.java class. Remove the CommandlineRunner support and add RestController support. In order to read the result a new jBPM Service Interface is injected, the RuntimeDataService. The code is as follows:

@SpringBootApplication
@RestController
public class Application  {

    @Autowired
    private ProcessService processService;
    @Autowired
    private RuntimeDataService runtimeDataService;

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @GetMapping("/hello")
    public ResponseEntity<String> sayHello(@RequestParam String name) throws Exception {
        Map<String, Object> vars = new HashMap<>();
        vars.put("processVar1", name);
        Long processInstanceId = processService.startProcess("business-application-kjar-1_0-SNAPSHOT", "SimpleProcess", vars);
        for ( VariableDesc var: runtimeDataService.getVariablesCurrentState(processInstanceId) ) {
            if ( var.getVariableId().equals("processVar1"))
                return ResponseEntity.ok(var.getNewValue());
        }
        return ResponseEntity.status(HttpStatus.FAILED_DEPENDENCY).body("Processing Error");
    }
}

The REST endpoint for this will be http://localhost:8090/hello and a name parameter is required. The final test URL could be http://localhost:8090/hello?name=World. Invoking with endppoint with your browser will return the result Hello World.