Package Exports

express-long-polling
express-long-polling/core.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (express-long-polling) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

express-long-polling

Library to implement long-polling API on express server.

Installation

npm i express-long-polling

Usage Example

See complete demo in server.ts, process-task.ts and submit-task.ts.

import express from 'express'
import cors from 'cors'
import { print } from 'listening-on'
import { LongPollingTaskQueue } from 'express-long-polling'

let app = express()

app.use(cors())
app.use(express.json())

let taskQueue = new LongPollingTaskQueue()

app.post('/task', (req, res) => {
  taskQueue.addTask({
    input: req.body,
    callback(output) {
      res.json({ output })
    },
  })
})

app.get('/task', (req, res) => {
  let task = taskQueue.getFirstTask()
  if (task) {
    res.json({ task })
  } else {
    taskQueue.waitTask(req)
  }
})

app.post('/task/result', (req, res) => {
  let { id, output } = req.body
  let task = taskQueue.dispatchResult(id, output)
  if (task) {
    res.status(201)
  } else {
    res.status(404)
  }
  res.json({})
})

let PORT = 8100
app.listen(PORT, () => {
  print(PORT)
})

Typescript Signature

import type { Request } from 'express'

export class LongPollingTask<Input, Output> {
  id: string
  input: Input
  dispatchResult(output: Output): void
}

export class LongPollingTaskQueue<Input, Output> {
  constructor(options?: { pollingInterval?: number })

  addTask(options: {
    id?: string
    input: Input
    callback: (output: Output) => void
  }): LongPollingTask<Input, Output>

  getFirstTask(): LongPollingTask<Input, Output> | null

  getRandomTask(): LongPollingTask<Input, Output> | null

  waitTask(req: Request): void

  dispatchResult(
    id: string,
    output: Output,
  ): LongPollingTask<Input, Output> | null
}

License

This project is licensed with BSD-2-Clause

This is free, libre, and open-source software. It comes down to four essential freedoms [ref]:

The freedom to run the program as you wish, for any purpose
The freedom to study how the program works, and change it so it does your computing as you wish
The freedom to redistribute copies so you can help others
The freedom to distribute copies of your modified versions to others