Workflow Entry Point

A Workflow Entry Point defines the starting point of a workflow within a controller method. Using @Workflow and @WorkflowSchema, you specify the workflow path and the sequence of steps. The entry point itself remains minimal, deferring all logic and data processing to the workflow’s steps.

Defining a Workflow Entry Point

A workflow entry point is created by applying the @Workflow decorator to a method, along with @WorkflowSchema to define the workflow’s steps.

Example (Parametric Path):

import { Workflow, WorkflowSchema, Param } from '@moostjs/event-fw';
import { Controller } from 'moost';

interface TQuadraticRootsContext {
  a: number;
  b: number;
  c: number;
  discriminant?: number;
  roots?: number[];
}

@Controller('math')
export class MathController {
  @Workflow("quadratic-roots/:a/:b/:c")
  @WorkflowSchema<TQuadraticRootsContext>([/* schema */])
  entryPoint(@Param('a') a: number, @Param('b') b: number, @Param('c') c: number) {
    // Keep entry point logic minimal.
    // In this example it makes sense to store parameters in wf context
  }
}

Key Points:

• @Workflow("..."): Defines the workflow's path.
• @WorkflowSchema(...): Specifies the workflow’s steps and conditions.
• Controller prefixes apply automatically to the workflow path.
• The entry point method ideally contains no significant logic.

Triggering a Workflow

Inject MoostWf from @moostjs/event-wf into your class and call .start() to begin the workflow.

import { Injectable } from 'moost';
import { MoostWf } from '@moostjs/event-wf';

@Injectable()
export class CalculationService {
  constructor(private readonly wf: MoostWf<TQuadraticRootsContext>) {}

  async findRoots(a: number, b: number, c: number) {
    await this.wf.start(`math/quadratic-roots/${a}/${b}/${c}`, { /* initial context */ });
  }
}

Passing Input to the Workflow

While param decorators (@Param) within the entry point method are one way to provide input to the workflow, there are multiple options for supplying data to workflows:

• Initial Context When Starting the Workflow:
  Supply an initial context object when calling wf.start().
• Sending Additional Input:
  Pass arbitrary input data during wf.start() calls.

More details on supplying input:
Working with Workflow Input

Conclusion

The workflow entry point simply identifies where a workflow begins. By combining @Workflow, @WorkflowSchema, and various input strategies, you can set up workflows to handle a wide range of scenarios, keeping the entry point itself lean and delegating all processing to well-structured workflow steps.