rest-gateway in Node.js

gateway-express/.gitignore

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+node_modules/
+.DS_Store

gateway-express/README.md

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+# Intro
+This is a REST gateway written in javascript with Node.js and Express.
+## Stage One
+For each incoming request, it issues a HTTP request to the RestServ and return HTML document.
+```
+GET /rest
+```
+## Stage Two
+For each incoming request, it issues n HTTP requests to the RestServ and return content in accept type.
+```
+POST /rest
+```
+# Quick Start
+0. Set up environment. [Download Node.js](https://nodejs.org/en/download/package-manager/#macos)
+1. Run `npm install` to install the dependencies, `express` (web framework for Node.js) and `request` (module to make http request).
+2. Start RestServer, checkout the binary file and execute the one that is suitable for you OS.
+3. Start RestGateway, either `npm start` (under gateway-express folder) or `npm --prefix gateway-express start` (under main folder).
+4. Send requests using `curl`.
+
+## Sample Request Commands
+
+- `curl -X GET localhost:5000/rest`
+- `curl -d '{"numRequests": 5}' -H "Content-Type: application/json" -X POST localhost:5000/rest`
+- `curl -d '{"numRequests": 5}' -H "Content-Type: application/json" -H "Accept:application/json" -X POST localhost:5000/rest`

gateway-express/gateway.js

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+const express = require('express');
+const request = require('request');
+
+const app = new express();
+const PORT = 5000;
+const RESTSERVERPORT = 8080;
+// Body parser request
+app.use(express.json({ extended: false}));
+
+// @route GET '/rest'
+// @desc  Stage One: issue single request to restserver
+app.get('/rest', (req, res) => {
+    try {
+        const options = {
+            url: `http://localhost:${RESTSERVERPORT}/request`,
+            method: 'GET'
+        };
+        request(options, (error, response, body) => {
+            if(error) console.error(error);
+            const info = JSON.parse(body);
+            // Set response type and response body
+            res.set({'Content-Type': 'text/html'});
+            res.send(`I RESTed for ${info.data} time units.`);
+        });
+    } catch (err) {
+        res.status(500).send('Server Error');
+    }
+});
+
+// @route  POST '/rest'
+// @desc   Stage Two: issue n requests to restserver, and return the content with accept content type.
+app.post('/rest', (req, res) => {
+    // Extract parameter from request body
+    const numRequests = req.body.numRequests;
+    let responseTime = [];
+    let requests = [];
+    // Declare a promise function
+    function issueSingleRequest(responseTime) {
+        const options = {
+            url: `http://localhost:${RESTSERVERPORT}/request`,
+            method: 'GET'
+        };
+        return new Promise((resolve, reject) => {
+            request(options, (error, response, body) => {
+                if(error) reject('error');
+                else {
+                    responseTime.push(JSON.parse(body).data);
+                    resolve();
+                }
+            });
+        });
+    };
+    for(let i = 0; i < numRequests; i++) {
+        requests.push(issueSingleRequest(responseTime));
+    };
+    // Issue n requests in parallel
+    Promise.all(requests).then(() => {
+        let totalTime = responseTime.reduce((a, b)=> {return a + b;}, 0);
+        // Test
+        //console.log(responseTime);
+
+        if(req.accepts('application/json')) {
+            res.json({"numRequests": `${numRequests}`, "milliseconds": `${totalTime}` })
+        } else {
+            res.set({'Content-Type': 'text/html'});
+            res.send(`I made ${numRequests} requests and it took ${totalTime} milliseconds`);
+        }
+    }).catch((error) => res.status(500).send('Server Error'))
+
+});
+
+app.listen(PORT, console.log(`Gateway is listening on port: ${PORT}`));
+