Invoking Workflow Scenarios

Invoking Workflow Using WebApp

Since workflow require a User Interface, a web-app is required as front-end to interact with user providing at least:

  • Selection of Workflows to Start
  • Show outstanding Tasks
  • Show recent Tasks

see Demo of WebApp

Invoking Proccess through API

To Invoke a process from your code:

API provides a security layer on top of the engine,See Security for more details.

    const api = new BPMNAPI(new BPMNServer(configuration,new Logger({ toConsole: false}),{cron:false}));

    let response=await api.engine.start('Leave Request',{type:'Vacation'},SystemUser);


    console.log('Invoking Buy');

    response = await api.engine.invoke({instanceId , elementId: 'task_Buy' },
        { model: 'Thunderbird', needsRepairs: false, needsCleaning: false },SystemUser);

The above code uses SystemUser, to define another user:

    const user1 =new SecureUser({ userName: 'user1', userGroups: ['Owner', 'Others']});

In real applications, you get userName and userGroups from you application UserAccess.

Invoking Remotely Using WebServices

NPM package ‘bpmn-client’ provide access to bpmn-server using remotely using webServices

const { BPMNServer } = require('bpmn-client');


async function test() {

    const client = new BPMNClient(process.env.HOST, process.env.PORT, process.env.API_KEY);

    let response = await client.engine.start('Buy Used Car');

Async Execution

The default behaviour is that engine.start and engine.invoke will execute the process in sequence specified in a synchronous fashion and returns control in one of these cases:

  1. Process has completed or Aborted; this happens when all active tokens come to completions
  2. All active tokens( threads) come to completion or wait state like in case of User Input, timers or Send Message

However, if you change this behaviour, so the engine execution return without waiting.

    const api = new BPMNAPI(new BPMNServer(configuration,new Logger({ toConsole: false}),{cron:false}));

    console.log('starting serviceTask');
    let response=await api.engine.start('serviceTask', { v1: 1, v2: 2 }, SystemUser, {noWait:true});


    console.log('immediate response id',;

In the above example; engine.start return immediatly, but other nodes will continue to execute

starting serviceTask
immediate response id d7df99ab-f0b5-4fdf-8ac3-2701d0bf9b79
 add service start: { v1: 1, v2: 2 }
Add Service 5 3
Add Service 33 25
delaying ... 5000
delayed is done.
appDelegate service1 is now complete input: { repeat: '100', inputVar2: undefined } output: 1 { v1: 1, v2: 2, result: 8, result2: 158 }
 service1 end: { v1: 1, v2: 2, result: 8, result2: 158 }