@asanrom/parallel-request-controller

Javascript client for Parallel request controller

This is the Javascript client library to connect to a Parallel Request Controller Server.

Installation

In order to install the library into your project, run the following command:

npm install @asanrom/parallel-request-controller

Usage

In order to connect to the PRC server, you must instantiate PRCClient and call the connect method.

Example:

import { PRCClient } from "@asanrom/parallel-request-controller";

const prcClient = new PRCClient({
  // PRC server base URL
  url: process.env.SERVER_URL || "ws://localhost:8080",
  // Authentication token
  authToken: process.env.AUTH_TOKEN || "",
  onServerError: (code, reason) => {
    // Called on a PRC server error
    console.error("[SERVER ERROR] " + code + ": " + reason);
  },
  onConnectionError: (err) => {
    // Called on a connection error
    console.error(err);
  },
});

prcClient.connect(); // Call connect to open the Websocket connections

Once you have instantiated PRCClient, you can call the startRequest method to indicate a request starting. It will return an object with a property limited that you can check in order to decide to drop the request. After the request is done, you must call the endRequest method of the client.

Example:

const MAX_PARALLEL_REQUESTS = 5;

async function handleRequest(request, response) {
  let prcRef;
  try {
    prcRef = await prcClient.startRequest(
      request.requestType,
      MAX_PARALLEL_REQUESTS
    );
  } catch (ex) {
    console.error(ex);
    response.status(500);
    response.send("Internal server error");
    return;
  }

  if (prcRef.limited) {
    // Request limit reached
    response.status(429);
    response.send("Request limit reached.");
    return;
  }

  try {
    // Handle request normally
    // ...
  } catch (ex) {
    console.error(ex);
    response.status(500);
    response.send("Internal server error");
  }

  prcClient.endRequest(prcRef);
}