diff --git a/ng1/config.json b/ng1/config.json
new file mode 100644
index 0000000..233b803
--- /dev/null
+++ b/ng1/config.json
@@ -0,0 +1,3 @@
+{
+    "mongoUrl": "mongodb://i399:salakala@i399-shard-00-00-otrzj.mongodb.net:27017,i399-shard-00-01-otrzj.mongodb.net:27017,i399-shard-00-02-otrzj.mongodb.net:27017/contacts?ssl=true&replicaSet=i399-shard-0&authSource=admin"
+}
diff --git a/ng1/dao.js b/ng1/dao.js
new file mode 100644
index 0000000..4ce42ff
--- /dev/null
+++ b/ng1/dao.js
@@ -0,0 +1,58 @@
+'use strict';
+
+const mongodb = require('mongodb');
+const ObjectID = require('mongodb').ObjectID;
+const COLLECTION = 'contacts';
+
+class Dao {
+
+    connect(url) {
+        return mongodb.MongoClient.connect(url)
+            .then(db => this.db = db);
+    }
+
+    findAll() {
+        return this.db.collection(COLLECTION).find().toArray();
+    }
+
+    findById(id) {
+        id = new ObjectID(id);
+        return this.db.collection(COLLECTION).findOne({_id:id});
+    }
+
+    update(id, data) {
+        id = new ObjectID(id);
+        data._id = id
+        return this.db.collection(COLLECTION)
+            .updateOne({_id:id}, data);
+    }
+
+    insert(data) {
+        return this.db.collection(COLLECTION)
+            .insertOne(data);
+    }
+
+    remove(id) {
+        id = new ObjectID(id);
+        return this.db.collection(COLLECTION)
+            .remove({_id:id})
+    }
+
+    removeMany(idList) {
+        var objectIds = [];
+        for (let id of idList) {
+            objectIds.push(new ObjectID(id))
+        }
+
+        return this.db.collection(COLLECTION)
+            .remove({_id: {$in: objectIds}})
+    }
+
+    close() {
+        if (this.db) {
+            this.db.close();
+        }
+    }
+}
+
+module.exports = Dao;
diff --git a/ng1/http-cat.js b/ng1/http-cat.js
new file mode 100644
index 0000000..08fa810
--- /dev/null
+++ b/ng1/http-cat.js
@@ -0,0 +1,18 @@
+// Express middelware for adding X-Http-Cat header using http.cat api from
+// https://http.cat/
+
+function middelware (req, res, next) {
+    var _writeHead = res.writeHead
+    res.writeHead = function(status) {
+        res.setHeader('X-Http-Cat', 'https://http.cat/' + status)
+        _writeHead.apply(res, arguments)
+    }
+
+    next()
+}
+
+
+module.exports = function(){
+    return middelware;
+}
+
diff --git a/ng1/package.json b/ng1/package.json
index 9791f79..14e42db 100644
--- a/ng1/package.json
+++ b/ng1/package.json
@@ -8,6 +8,7 @@
     "body-parser": "^1.17.1",
     "express": "^4.15.2",
     "morgan": "^1.8.2",
+    "mongodb": "^2.2.28",
     "nodemon": "^1.11.0"
   }
 }
diff --git a/ng1/server.js b/ng1/server.js
index bd0b1ac..e700e33 100644
--- a/ng1/server.js
+++ b/ng1/server.js
@@ -3,9 +3,16 @@
 const express = require('express');
 const bodyParser = require('body-parser');
 const morgan = require('morgan');
+const ObjectID = require('mongodb').ObjectID;
 
+const HttpCat = require('./http-cat.js')
+const Dao = require('./dao.js');
+const config = require('./config.json');
+
+const dao = new Dao();
 const app = express();
 
+app.use(HttpCat());
 app.use(morgan('dev'));
 app.set('etag', false);
 app.use(bodyParser.json()); // before request handlers
@@ -16,122 +23,128 @@ app.get('/api/contacts', getContacts);
 app.get('/api/contacts/:id', getContact);
 app.post('/api/contacts', addContact);
 app.put('/api/contacts/:id', changeContact);
-app.post('/api/contacts/delete', deleteMultibleContact);
+app.post('/api/contacts/delete', deleteMultibleContacts);
 app.delete('/api/contacts/:id', deleteContact);
 
-var contacts = [
-    {
-      "_id": 1,
-      "name": "Jack",
-      "phone": "123"
-    },
-    {
-      "_id": 2,
-      "name": "Jill",
-      "phone": "456"
-    },
-    {
-      "_id": 3,
-      "name": "Mary",
-      "phone": "789"
-    }
-]
-var lastContactId = 3;
-
 app.use(errorHandler); // after request handlers
 
-app.listen(3000, () => console.log('Server is running on port 3000'));
+dao.connect(config.mongoUrl)
+.then(() => {
+    app.listen(3000, () => console.log('Server is running on port 3000'));
+}).catch(err => {
+    console.log("MongoDB connection failed: ");
+    console.log(err)
+    process.exit(1);
+})
+
 
 function errorHandler(error, request, response, next) { // there must be 4 arguments
+    console.log(error)
     response.status(500).send('error: ' + error.toString());
 }
 
 function getContacts(req, resp) {
-    resp.set('Content-Type', 'application/json');
-    resp.json(contacts);
+    dao.findAll().then(data => resp.json(data));
 }
 
 function getContact(req, resp) {
     var id = req.params.id;
-    resp.set('Content-Type', 'application/json');
-    for (let contact of contacts) {
-        if (contact._id == id) {
-            resp.json(contact);
-            return;
-        }
+
+    if (!ObjectID.isValid(id)) {
+        resp.status(400).json("Invalid id");
+        return;
     }
-    resp.status(404).end("Contact Not Found");
+
+    dao.findById(id).then(data => {
+        resp.json(data);
+    }).catch(err => {
+        console.log(err);
+        resp.status(404).json(err.toString());
+    });
 }
 
-function addContact(req, resp) {
+function addContact(req, resp, next) {
     var contact = req.body;
+    if (contact.name == null ) {
+        resp.status(400).json("Can't add a contact without a name");
+        return;
+    }
+
     var sanitizedContact = {
-        "_id": ++lastContactId,
         "name": contact.name,
         "phone": contact.phone
     }
 
-    contacts.push(sanitizedContact)
-
-    resp.status(200).json(sanitizedContact);
+    dao.insert(sanitizedContact).then((data) => {
+        resp.status(201);
+        resp.location("/api/contacts/"+data.insertedId);
+        dao.findById(data.insertedId).then(insertedContact => {
+            resp.json(insertedContact);
+        });
+    }).catch(err => {
+        console.log(err);
+        next(err);
+    })
 }
 
 function changeContact(req, resp) {
     var id = req.params.id;
-    var changedContact = req.body;
+    var contact = req.body;
 
-    for (let contact of contacts) {
-        if (contact._id == id) {
-            contact.name = changedContact.name;
-            contact.phone = changedContact.phone
-            resp.status(200).end("Changed");
-            return;
-        }
+    if (!ObjectID.isValid(id)) {
+        resp.status(400).json("Invalid id");
+        return;
     }
-    resp.status(404).end("Contact Not Found");
+
+    if (contact.name == null) {
+        resp.status(400).json("Contact must have a name");
+        return;
+    }
+
+    var sanitizedContact = {
+        "name": contact.name,
+        "phone": contact.phone
+    }
+
+    dao.update(id, sanitizedContact).then(data => {
+       resp.status(200).end("Changed");
+    }).catch(err => {
+        console.log(err);
+        resp.status(404).end("Contact Not Found");
+    });
+
 }
 
 function deleteContact(req, resp) {
     var id = req.params.id;
-    for (let i=0; i < contacts.length; i++){
-        var contact = contacts[i];
-        if (contact._id == id){
-            contacts.splice(i, 1);
-            resp.status(200).end("Deleted");
+    if (!ObjectID.isValid(id)) {
+        resp.status(400).json("Invalid id");
+        return;
+    }
+
+    dao.remove(id).then(data => {
+        resp.status(200).json("Deleted");
+    }).catch(err => {
+        console.log(err);
+        resp.status(404).end("Contact Not Found");
+    })
+}
+
+function deleteMultibleContacts(req, resp) {
+    var contactIds = req.body;
+
+    for (let id of contactIds) {
+        if (!ObjectID.isValid(id)) {
+            resp.status(400).json("Invalid ID in the list");
             return;
         }
     }
-    resp.status(404).end("Contact Not Found");
-}
-
-function deleteMultibleContact(req, resp) {
-    var contactIds = req.body;
-    var invalidIds = [];
-
-    while (true){
-        let id = contactIds.pop()
-        if (!id){
-            break;
-        }
-        for (let i=0; i < contacts.length; i++){
-            var contact = contacts[i];
-            if (contact._id == id){
-                contacts.splice(i, 1);
-                id = null;
-            }
-        }
-
-        if (id){
-            invalidIds.push(id);
-        }
-    }
-
-    if(invalidIds.length == 0){
-        resp.status(200).end("Deleted");
-    } else {
-        resp.status(404);
-        resp.json(invalidIds);
-    }
 
+    dao.removeMany(contactIds).then(data => {
+        resp.status(200).json("Deleted");
+    }).catch(err => {
+        console.log(err);
+        resp.status(400).json("Failed to delete some or all of the contacts" + err.toString());
+    })
 
 }