temporal-rest
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0.5.1 • Public • Published

temporal-rest

Creates an Express middleware router that automatically exposes endpoints for Temporal Workflows, Signals, and Queries.

Usage

Suppose you have some Temporal Workflows, Queries, and Signals in a workflows.js file:

'use strict';

const wf = require('@temporalio/workflow');

exports.unblockSignal = wf.defineSignal('unblock');
exports.isBlockedQuery = wf.defineQuery('isBlocked');

exports.unblockOrCancel = async function unblockOrCancel() {
  let isBlocked = true;
  wf.setHandler(exports.unblockSignal, () => void (isBlocked = false));
  wf.setHandler(exports.isBlockedQuery, () => isBlocked);
  console.log('Blocked');
  try {
    await wf.condition(() => !isBlocked);
    console.log('Unblocked');
  } catch (err) {
    if (err instanceof wf.CancelledFailure) {
      console.log('Cancelled');
    }
    throw err;
  }
}

Temporal-rest exports a function that returns an Express router with an endpoint for every Workflow, Signal, and Query.

const { WorkflowClient } = require('@temporalio/client');
const workflows = require('./workflows');

const createExpressMiddleware = require('temporal-rest');
const express = require('express');

const app = express();

// Router has the below endpoints:
// - POST /workflow/unblockOrCancel
// - PUT /signal/unblock
// - GET /query/isBlocked
const router = createExpressMiddleware(workflows, new WorkflowClient(), 'my-task-queue');
app.use(router);

Note that temporal-rest only registers endpoints for exported Signals and Queries. If you want to register an endpoint for a Signal or Query, make sure you export it from workflows.ts / workflows.js:

// Temporal-rest will create a `PUT /signal/unblock/:workflowId` endpoint
exports.unblockSignal = wf.defineSignal('unblock');

// Temporal-rest will NOT create a `PUT /signal/otherSignal/:workflowId` endpoint,
// because this Signal isn't exported.
const otherSignal = wf.defineSignal('otherSignal');

temporal-rest adds the below endpoints for every exported Workflow:

  • POST /workflow/<workflowName>: create a new instance of the given Workflow. Use uuid to generate the Workflow id
  • POST /workflow/<workflowName>/:workflowId: create a new instance of the given Workflow with the given Workflow id

temporal-rest adds the below endpoints for every exported Query:

  • GET /query/<queryName>/:workflowId: execute the Query with the given name against the given Workflow id

temporal-rest adds the below endpoints for every exported Signal:

  • PUT /signal/<signalName>/:workflowId: execute the Signal with the given name against the given Workflow id

Passing Arguments

For Signals and Workflows, temporal-rest passes the HTTP request body as the first parameter to the Signal or Workflow. For example, suppose you have the below workflows.js file.

'use strict';

const { defineSignal, defineQuery, setHandler, condition } = require('@temporalio/workflow');

exports.setDeadlineSignal = defineSignal('setDeadline');
exports.timeLeftQuery = defineQuery('timeLeft');

exports.countdownWorkflow = async function countdownWorkflow({ delay }) {
  delay = delay == null ? 1500 : delay;
  let deadline = Date.now() + delay;
  
  setHandler(exports.setDeadlineSignal, (data) => {
    // send in new deadlines via Signal
    deadline = data.deadline;
  });
  setHandler(exports.timeLeftQuery, (data) => {
    if (data.seconds === 'true') {
      return Math.floor((deadline - Date.now()) / 1000);
    }
    return deadline - Date.now();
  });
  
  await condition(() => (deadline - Date.now()) < 0);
}

To pass a delay argument to countdownWorkflow(), you should send a POST /workflow/countdownWorkflow request with {"delay": 3000} as the request body. Temporal-rest currently assumes the request body is JSON, and passes the parsed request body as the first argument to the Workflow. For example, you can use the below CURL command.

curl -X POST http://localhost:3000/workflow/countdownWorkflow -d '{"delay": 3000}'

Similarly, you can pass arguments to Signals. The below CURL command sets deadline to 3000 in setDeadlineSignal:

curl -X PUT http://localhost:3000/signal/setDeadline -d '{"deadline": 3000}'

For Queries, temporal-rest passes req.query as the first argument. For example, the below CURL command calls timeLeftQuery({ seconds: 'true' }):

curl http://localhost:3000/query/timeLeft?seconds=true

For Development

Running Tests

  1. Make sure Temporal server is running
  2. Run npm install
  3. Run npm test

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0.5.1

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