initial commit

code/expresso/index.js

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+/**
+ *  Webservice mit Express
+ *  WBE-Praktikum
+ */
+
+var express = require('express')
+var app = express()
+
+//  Fehlerobjekt anlegen
+//
+function error(status, msg) {
+  var err = new Error(msg)
+  err.status = status
+  return err
+}
+
+//  Zufällige ID erzeugen, Quelle:
+//  https://stackoverflow.com/questions/6860853/generate-random-string-for-div-id#6860916
+//
+function guidGenerator() {
+  var S4 = function() {
+    return (((1+Math.random())*0x10000)|0).toString(16).substring(1)
+  }
+  return (S4()+S4()+"-"+S4()+"-"+S4()+"-"+S4()+"-"+S4()+S4()+S4())
+}
+
+//  API-Key überprüfen
+// 
+app.use('/api', function(req, res, next){
+  var key = req.query['api-key']
+  
+  // Key fehlt
+  if (!key) { 
+    return next(error(400, 'api key required'))
+  }
+  // Key falsch
+  if (!~apiKeys.indexOf(key)) {
+    return next(error(401, 'invalid api key'))
+  }
+  // korrekter Key
+  req.key = key
+  next()
+})
+
+//  JSON-Daten akzeptieren
+app.use(express.json())
+
+//  gültige API-Keys
+var apiKeys = ['wbeweb']
+
+//  unsere tolle in-memory Datenbank :)
+var data = {1234567890: {demodata: "wbe is an inspiring challenge"}}
+
+//  GET-Request bearbeiten
+//
+app.get('/api/data/:id', function(req, res, next){
+  var id = req.params.id
+  var result = data[id]
+
+  if (result) res.send(result)
+  else next()
+})
+
+//  POST-Request bearbeiten
+//
+app.post('/api/data', function (req, res, next) {
+  let id = guidGenerator()
+  data[id] = req.body
+  res.send({id})
+})
+
+//  Middleware mit vier Argumenten wird zur Fehlerbehandlung verwendet
+//
+app.use(function(err, req, res, next){
+  res.status(err.status || 500)
+  res.send({ error: err.message })
+})
+
+//  Catch-all: wenn keine vorangehende Middleware geantwortet hat, wird
+//  hier ein 404 (not found) erzeugt
+//
+app.use(function(req, res){
+  res.status(404)
+  res.send({ error: "not found" })
+})
+
+app.listen(3000)
+console.log('Express started on port 3000')
+
+
+

code/expresso/package.json

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+{
+  "name": "expresso",
+  "version": "1.0.0",
+  "description": "Express Demo Project",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "bkrt",
+  "license": "ISC",
+  "dependencies": {
+    "express": "^4.17.1"
+  }
+}

code/fileserver/fileserver.js

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+const {createServer} = require("http");
+
+const methods = Object.create(null);
+
+createServer((request, response) => {
+  let handler = methods[request.method] || notAllowed;
+  handler(request)
+    .catch(error => {
+      if (error.status != null) return error;
+      return {body: String(error), status: 500};
+    })
+    .then(({body, status = 200, type = "text/plain"}) => {
+       response.writeHead(status, {"Content-Type": type});
+       if (body && body.pipe) body.pipe(response);
+       else response.end(body);
+    });
+}).listen(8000);
+
+async function notAllowed(request) {
+  return {
+    status: 405,
+    body: `Method ${request.method} not allowed.`
+  };
+}
+
+var {parse} = require("url");
+var {resolve, sep} = require("path");
+
+var baseDirectory = process.cwd();
+
+function urlPath(url) {
+  let {pathname} = parse(url);
+  let path = resolve(decodeURIComponent(pathname).slice(1));
+  if (path != baseDirectory &&
+      !path.startsWith(baseDirectory + sep)) {
+    throw {status: 403, body: "Forbidden"};
+  }
+  return path;
+}
+
+const {createReadStream} = require("fs");
+const {stat, readdir} = require("fs").promises;
+const mime = require("mime");
+
+methods.GET = async function(request) {
+  let path = urlPath(request.url);
+  let stats;
+  try {
+    stats = await stat(path);
+  } catch (error) {
+    if (error.code != "ENOENT") throw error;
+    else return {status: 404, body: "File not found"};
+  }
+  if (stats.isDirectory()) {
+    return {body: (await readdir(path)).join("\n")};
+  } else {
+    return {body: createReadStream(path),
+            type: mime.getType(path)};
+  }
+};
+
+const {rmdir, unlink} = require("fs").promises;
+
+methods.DELETE = async function(request) {
+  let path = urlPath(request.url);
+  let stats;
+  try {
+    stats = await stat(path);
+  } catch (error) {
+    if (error.code != "ENOENT") throw error;
+    else return {status: 204};
+  }
+  if (stats.isDirectory()) await rmdir(path);
+  else await unlink(path);
+  return {status: 204};
+};
+
+const {createWriteStream} = require("fs");
+
+function pipeStream(from, to) {
+  return new Promise((resolve, reject) => {
+    from.on("error", reject);
+    to.on("error", reject);
+    to.on("finish", resolve);
+    from.pipe(to);
+  });
+}
+
+methods.PUT = async function(request) {
+  let path = urlPath(request.url);
+  await pipeStream(request, createWriteStream(path));
+  return {status: 204};
+};
+
+const {mkdir} = require("fs").promises;
+
+methods.MKCOL = async function(request) {
+  let path = urlPath(request.url);
+  let stats;
+  try {
+    stats = await stat(path);
+  } catch (error) {
+    if (error.code != "ENOENT") throw error;
+    await mkdir(path);
+    return {status: 204};
+  }
+  if (stats.isDirectory()) return {status: 204};
+  else return {status: 400, body: "Not a directory"};
+};

code/fileserver/package.json

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+{
+  "name": "fileserver",
+  "version": "1.0.0",
+  "description": "Demo Fileserver",
+  "main": "fileserver.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "Eloquent JavaScript",
+  "license": "ISC",
+  "dependencies": {
+    "mime": "^2.2.0"
+  }
+}