WorkIt
Motivation
We needed a framework to help us quickly build workers used to execute tasks.
This package can be useful because:
- Experiment and choose the Camunda platform you want without rewritting the business logic.
- At this moment, Zeebe doesn't provide all BPMN components. Zeebe is new and some unexpected bugs can appear during development so we can easily revert back to the the former platform if an issue was to rise.
- Instead of depending directly from a Camunda client, this project provides an abstraction layer. This way it’s easier to change the client or to make your own.
- You want to have a worker standardization.
- Uniformisation. Indeed, you can use both platforms depending project needs.
- Added features like automated tracing.
- This package enforce feature parity between Zeebe and Camunda BPM through the client libraries. Some features exposed to the Camunda BPM platform are not presents in this package because we couldn't provide them if we switch to Zeebe. This limitation is to guide developers to prepare migration.
Quickstart
Documentation
- Documentation is available in this folder
- Comprehensive API documentation is available online and in the
docs
subdirectory - Examples
Packages
Packages will move under @villedemontreal organization after the 4.2.0 version. Packages must be renamed in your package.json file.
For example, instead of workit-camunda
it will be @villedemontreal/workit-camunda
.
API
Package | Description |
---|---|
workit-types | This package provides TypeScript interfaces and enums for the Workit core model. |
workit-core | This package provides default and no-op implementations of the Workit types |
Implementation / Clients
Package | Description |
---|---|
workit-bpm-client | This module provides a full control over the Camunda Bpm platform. It use camunda-external-task-client-js by default. |
workit-zeebe-client | This module provides a full control over the Zeebe platform. It use zeebe-node and zeebe-elasticsearch-client by default. |
workit-camunda | This module allows you to switch between Camunda BPM and Zeebe easily. It use workit-bpm-client and workit-zeebe-client by default. |
Installing
npm i @villedemontreal/workit-camunda
or using the generator below
Yo!
This generator will help you during your development with this library. It provides handy tools.
npm i -g @villedemontreal/workit-cli
Install a fresh new project
workit init
Generate tasks from your existing BPMN
workit create task --file /your/path.bpmn
Generate new task
workit create task
How to use
Switching between Zeebe and the bpmn platform is easy as specifying a TAG
to the IoC.
Run worker
const worker = IoC.get<Worker>(CORE_IDENTIFIER.worker, TAG.camundaBpm); // or TAG.zeebe
worker.start();
worker.run();
Deploy a workflow
const manager = IoC.get<IWorkflowClient>(CORE_IDENTIFIER.client_manager, TAG.camundaBpm); // or TAG.zeebe
const fullpath = `${process.cwd()}/sample/BPMN_DEMO.bpmn`;
await manager.deployWorkflow(fullpath);
Get workflows
Zeebe: You will need elasticsearch instance.
const manager = IoC.get<IWorkflowClient>(CORE_IDENTIFIER.client_manager, TAG.camundaBpm); // or TAG.zeebe
await manager.getWorkflows()
Get a workflow
Zeebe: You will need elasticsearch instance.
const manager = IoC.get<IWorkflowClient>(CORE_IDENTIFIER.client_manager, TAG.camundaBpm); // or TAG.zeebe
await manager.getWorkflow({ bpmnProcessId: "DEMO" });
Update variables
const manager = IoC.get<IWorkflowClient>(CORE_IDENTIFIER.client_manager, TAG.camundaBpm); // or TAG.zeebe
await manager.updateVariables({
processInstanceId: "5c50c48e-4691-11e9-8b8f-0242ac110002",
variables: { amount: 1000 }
});
Publish message
const manager = IoC.get<IWorkflowClient>(CORE_IDENTIFIER.client_manager, TAG.camundaBpm); // or TAG.zeebe
await manager.publishMessage({
correlation: {},
name: "catching",
variables: { amount: 100 },
timeToLive: undefined, // only supported for Zeebe
messageId: "5c50c48e-4691-11e9-8b8f-0242ac110002"
});
Create workflow instance
const manager = IoC.get<IWorkflowClient>(CORE_IDENTIFIER.client_manager, TAG.camundaBpm); // or TAG.zeebe
await manager.createWorkflowInstance({
bpmnProcessId: "MY_BPMN_KEY",
variables: {
hello: "world"
}
});
Cancel workflow instance
const manager = IoC.get<IWorkflowClient>(CORE_IDENTIFIER.client_manager, TAG.camundaBpm); // or TAG.zeebe
await manager.cancelWorkflowInstance("4651614f-4b3c-11e9-b5b3-ee5801424400");
Resolve incident
const manager = IoC.get<IWorkflowClient>(CORE_IDENTIFIER.client_manager, TAG.camundaBpm); // or TAG.zeebe
await manager.resolveIncident("c84fce6c-518e-11e9-bd78-0242ac110003");
Define tasks (your bpmn activities)
You can define many tasks to one worker. It will handle all messages and will route to the right tasks.
export class HelloWorldTask extends TaskBase<IMessage> {
// You can type message like IMessage<TBody, TProps> default any
public execute(message: IMessage): Promise<IMessage> {
const { properties } = message;
console.log(`Executing task: ${properties.activityId}`);
console.log(`${properties.bpmnProcessId}::${properties.processInstanceId} Servus!`);
// put your business logic here
return Promise.resolve(message);
}
}
enum LOCAL_IDENTIFIER {
// sample_activity must match the activityId in your bpmn
sample_activity= 'sample_activity'
}
// Register your task
IoC.bindTo(HelloWorldTask, LOCAL_IDENTIFIER.sample_activity);
You can even make complex binding like
IoC.bindTask(HelloWorldTaskV2, LOCAL_IDENTIFIER.activity1, { bpmnProcessId: BPMN_PROCESS_ID, version: 2 });
If you have installed workit-cli
, you can do workit create task
and everything will be done for you.
Worker life cycle and events
const worker = IoC.get<Worker>(CORE_IDENTIFIER.worker, TAG.zeebe); // or TAG.camundaBpm
worker.once('starting', () => {
// slack notification
});
worker.once('stopping', () => {
// close connections
});
worker.once('stopped', () => {
// slack notification
});
const handler = worker.getProcessHandler();
handler.on('message', (msg: IMessage) => {
// log/audit
});
handler.on('message-handled', (err: Error, msg: IMessage) => {
if (err) {
// something wrong
} else {
// everything is fine
}
});
worker.start();
worker.run(); // Promise
worker.stop(); // Promise
Interceptors
const workerConfig = {
interceptors: [
async (message: IMessage): Promise<IMessage> => {
// do something before we execute task.
return message;
}
]
};
IoC.bindToObject(workerConfig, CORE_IDENTIFIER.worker_config);
OpenTelemetry
By default, we bound a NoopTracer
but you can provide your own and it must extend Tracer.We strongly recommand to use this kind of pattern in your task: Domain Probe pattern. But here an example:
// Simply bind your custom tracer object like this
IoC.bindToObject(tracer, CORE_IDENTIFIER.tracer);
export class HelloWorldTask extends TaskBase<IMessage> {
private readonly _tracer: Tracer;
constructor(tracer: Tracer) {
this._tracer = tracer
}
public async execute(message: IMessage): Promise<IMessage> {
const { properties } = message;
console.log(`Executing task: ${properties.activityId}`);
console.log(`${properties.bpmnProcessId}::${properties.processInstanceId} Servus!`);
// This call will be traced automatically
const response = await axios.get('https://jsonplaceholder.typicode.com/todos/1');
// you can also create a custom trace like this :
const currentSpan = tracer.getCurrentSpan();
const span = this._tracer.startSpan('customSpan', {
parent: currentSpan,
kind: SpanKind.CLIENT,
attributes: { key: 'value' },
});
console.log();
console.log('data:');
console.log(response.data);
// put your business logic here
// finish the span scope
span.end();
return Promise.resolve(message);
}
}
You can look to sample
folder where we provide an example (parallel.ts) using Jaeger.
See get started section with OpenTelemetry
Define your config for the platform you want to use
const configBase: ICamundaConfig = {
workerId: 'demo',
baseUrl: `__undefined__`,
topicName: 'topic_demo'
};
// For Camunda BPM platform
const bpmnPlatformClientConfig = { ...configBase, baseUrl: 'http://localhost:8080/engine-rest', maxTasks: 32, autoPoll: false, use: [] };
IoC.bindToObject(bpmnPlatformClientConfig, CORE_IDENTIFIER.camunda_external_config);
// For Zeebe platform
const zeebeClientConfig = { ...configBase, baseUrl: 'localhost:2650', timeout: 2000 };
// For Zeebe exporter (Elasticsearch instance)
const zeebeElasticExporterConfig = {
url: `http://localhost:9200`,
};
IoC.bindToObject(zeebeClientConfig, CORE_IDENTIFIER.zeebe_external_config);
IoC.bindToObject(zeebeElasticExporterConfig, CORE_IDENTIFIER.zeebe_elastic_exporter_config)
Define your strategies in case of failure or success
By default, we define simple strategy for success or failure. We strongly recommend you to provide yours as your app trigger specific exceptions. Strategies are automatically handled. If an exeption is bubble up from the task, failure strategy is raised, otherwise it's success.
// the idea is to create your own but imagine that your worker works mainly with HTTP REST API
class ServerErrorHandler extends ErrorHandlerBase {
constructor(config: { maxRetries: number }) {
super(config);
}
public isHandled(error: IErrorResponse<IResponse<IApiError>>): boolean {
return error.response.status >= 500;
}
public handle(error: IErrorResponse<IResponse<IApiError>>, message: IMessage): Failure {
const retries = this.getRetryValue(message);
return new Failure(error.message, this.buildErrorDetails(error, message), retries, 2000 * retries);
}
}
// You got the idea...
// You could create also
// BadRequestErrorHandler
// TimeoutErrorHandler
// UnManagedErrorHandler
// ...
// Then you could build your strategy
/// "FailureStrategy" implements "IFailureStrategy", this interface is provided by workit-camunda
const strategy = new FailureStrategy([
new AxiosApiErrorHandler(errorConfig, [
new BadRequestErrorHandler(errorConfig),
new TimeoutErrorHandler(errorConfig),
new ServerErrorHandler(errorConfig),
new UnManagedErrorHandler(errorConfig),
//...
]),
new ErrorHandler(errorConfig)
]);
// worker will use your new strategy
IoC.bindToObject(strategy, CORE_IDENTIFIER.failure_strategy);
Running the tests
We use Jest.
npm test
Built With
- zeebe-node - nodejs client for Zeebe
- camunda-external-task-client-js - nodejs client for Camunda BPM
- inversify - Dependency injection
- opentelemetry - add instrumentation to the operations (provides a single set of APIs, libraries to capture distributed traces)
Philosophy
- Allow Javascript developers to write code that adheres to the SOLID principles.
- Facilitate and encourage the adherence to the best OOP and IoC practices.
- Add as little runtime overhead as possible.
Kubernetes
Zeebe
TODO: provide helm chart. But in the meantime, you can do for development:
kubernetes/run
Docker
Zeebe
In your terminal
docker/run
Bpmn platform
docker run -d --name camunda -p 8080:8080 camunda/camunda-bpm-platform:latest
// Go: http://localhost:8080/camunda - user/password : `demo/demo`
TODO
Click to expand
- Add tests
- Improve docs
- Make sample and confirm compatibility with DMN
- Adding a common exception error codes between Manager clients
- Add metrics by using prometheus lib
Versionning
We use SemVer for versioning. For the versions available, see the tags on this repository.
workit-* | Zeebe | Camunda BPM |
---|---|---|
>=4.0.5 | 0.22.1 | 7.6 to latest |
3.2.x <=4.0.4 | 0.20.x < 0.20.1 | 7.6 to latest |
3.1.x | 0.20.x < 0.20.1 | 7.6 to latest |
2.2.0 | 0.20.x < 0.20.1 | 7.6 to latest |
2.1.0 | 0.19.x | 7.6 to latest |
2.0.1 | 0.18.x | 7.6 to latest |
< 1.0.0 | <= 0.17.0 | 7.6 to latest |
Maintainers
See the list of contributors who participated in this project.
Contributing
Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.
License
This project is licensed under the MIT License - see the LICENSE file for details
Acknowledgments
- Josh Wulf - zeebe-node inspired me during
workit-cli
development