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"
+  }
+}