diff --git a/catalogue/package.json b/catalogue/package.json
index 04e2a35..2d48701 100644
--- a/catalogue/package.json
+++ b/catalogue/package.json
@@ -11,10 +11,11 @@
   "dependencies": {
       "body-parser": "^1.18.1",
       "express": "^4.15.4",
-      "mongodb": "^2.2.33",
+      "mongodb": "2.2.33",
       "pino": "^5.10.8",
       "express-pino-logger": "^4.0.0",
       "pino-pretty": "^2.5.0",
-      "@instana/collector": "^1.28.0"
+      "@instana/collector": "^1.28.0",
+      "mathjs": "^6.6.4"
   }
 }
diff --git a/catalogue/server.js b/catalogue/server.js
index 9d4b773..79a8c6b 100644
--- a/catalogue/server.js
+++ b/catalogue/server.js
@@ -26,7 +26,80 @@ const expLogger = expPino({
 
 // MongoDB
 var productsCollection;
-var mongoConnected = false;
+
+const port = process.env.CATALOGUE_SERVER_PORT || '8080';
+
+// set up Mongo
+function mongoConnectionPromise() {
+    return new Promise(function() {
+        var mongoURL;
+
+        if (process.env.VCAP_SERVICES) {
+            const bindingName = 'catalogue_database';
+
+            connectionDetails = null;
+
+            console.log('Env var \'VCAP_SERVICES\' found, scanning for \'catalogue_database\' service binding');
+
+            for (let [key, value] of Object.entries(JSON.parse(process.env.VCAP_SERVICES))) {
+                try {
+                    connectionDetails = value.find(function(binding) {
+                        return bindingName == binding.binding_name && binding.credentials;
+                    }).credentials;
+            
+                    if (!connectionDetails) {
+                        throw new Error(`Cannot find a service binding with name '${bindingName}'`);
+                    }
+
+                    const username = connectionDetails.username;
+                    const password = connectionDetails.password;
+
+                    const normalizedAuthDetails = `${encodeURIComponent(username)}:${encodeURIComponent(password)}`;
+
+                    mongoURL = connectionDetails.uri.replace(`${username}:${password}`, normalizedAuthDetails);
+            } catch (err) {
+                    console.log('Cannot process key \'' + key + '\' of \'VCAP_SERVICES\'', err);
+                    throw err;
+                }
+            }
+        } else if (process.env.MONGO_URL) {
+            mongoURL = process.env.MONGO_URL;
+
+            console.log('MongoDB URI found in \'MONGO_URL\': ' + mongoURL);
+        } else {
+            mongoURL = 'mongodb://mongodb:27017/catalogue';
+
+            console.log('Using default MongoDB URI');
+        }
+
+        if (!mongoURL) {
+            throw new Error('MongoDB connection data missing');
+        }
+
+        return mongoClient.connect(mongoURL);
+    })
+    .then(function(db) {
+        productsCollection = db.collection('products');
+
+        db.on('close', function() {
+            logger.error('Disconnected from the MongoDB database, reconnecting...', e);
+
+            mongoConnect();
+        })
+    })
+    .then(function() {
+        logger.info('MongoDB connected');
+    })
+    .catch(function(err) {
+        console.log(`Cannot connect to MongoDB: ${err}`);
+    });
+};
+
+async function mongoConnect() {
+    await mongoConnectionPromise();
+}
+
+mongoConnect();
 
 const app = express();
 
@@ -51,163 +124,64 @@ app.get('/health', (req, res) => {
 
 // all products
 app.get('/products', (req, res) => {
-    if(mongoConnected) {
-        productsCollection.find({}).toArray().then((products) => {
-            res.json(products);
-        }).catch((e) => {
-            req.log.error('ERROR', e);
-            res.status(500).send(e);
-        });
-    } else {
-        req.log.error('database not available');
-        res.status(500).send('database not avaiable');
-    }
+    productsCollection.find({}).toArray().then((products) => {
+        res.json(products);
+    }).catch((e) => {
+        req.log.error('ERROR', e);
+        res.status(500).send(e);
+    });
 });
 
 // product by SKU
 app.get('/product/:sku', (req, res) => {
-    if(mongoConnected) {
-        productsCollection.findOne({sku: req.params.sku}).then((product) => {
-            req.log.info('product', product);
-            if(product) {
-                res.json(product);
-            } else {
-                res.status(404).send('SKU not found');
-            }
-        }).catch((e) => {
-            req.log.error('ERROR', e);
-            res.status(500).send(e);
-        });
-    } else {
-        req.log.error('database not available');
-        res.status(500).send('database not available');
-    }
+    productsCollection.findOne({sku: req.params.sku}).then((product) => {
+        req.log.info('product', product);
+        if(product) {
+            res.json(product);
+        } else {
+            res.status(404).send('SKU not found');
+        }
+    }).catch((e) => {
+        req.log.error('ERROR', e);
+        res.status(500).send(e);
+    });
 });
 
 // products in a category
 app.get('/products/:cat', (req, res) => {
-    if(mongoConnected) {
-        productsCollection.find({ categories: req.params.cat }).sort({ name: 1 }).toArray().then((products) => {
-            if(products) {
-                res.json(products);
-            } else {
-                res.status(404).send('No products for ' + req.params.cat);
-            }
-        }).catch((e) => {
-            req.log.error('ERROR', e);
-            res.status(500).send(e);
-        });
-    } else {
-        req.log.error('database not available');
-        res.status(500).send('database not avaiable');
-    }
+    productsCollection.find({ categories: req.params.cat }).sort({ name: 1 }).toArray().then((products) => {
+        if(products) {
+            res.json(products);
+        } else {
+            res.status(404).send('No products for ' + req.params.cat);
+        }
+    }).catch((e) => {
+        req.log.error('ERROR', e);
+        res.status(500).send(e);
+    });
 });
 
 // all categories
 app.get('/categories', (req, res) => {
-    if(mongoConnected) {
-        productsCollection.distinct('categories').then((categories) => {
-            res.json(categories);
-        }).catch((e) => {
-            req.log.error('ERROR', e);
-            res.status(500).send(e);
-        });
-    } else {
-        req.log.error('database not available');
-        res.status(500).send('database not available');
-    }
+    productsCollection.distinct('categories').then((categories) => {
+        res.json(categories);
+    }).catch((e) => {
+        req.log.error('ERROR', e);
+        res.status(500).send(e);
+    });
 });
 
 // search name and description
 app.get('/search/:text', (req, res) => {
-    if(mongoConnected) {
-        productsCollection.find({ '$text': { '$search': req.params.text }}).toArray().then((hits) => {
-            res.json(hits);
-        }).catch((e) => {
-            req.log.error('ERROR', e);
-            res.status(500).send(e);
-        });
-    } else {
-        req.log.error('database not available');
-        res.status(500).send('database not available');
-    }
+    productsCollection.find({ '$text': { '$search': req.params.text }}).toArray().then((hits) => {
+        res.json(hits);
+    }).catch((e) => {
+        req.log.error('ERROR', e);
+        res.status(500).send(e);
+    });
 });
 
-// set up Mongo
-function mongoConnect() {
-    return new Promise((resolve, reject) => {
-        var mongoURL;
-
-        if (process.env.VCAP_SERVICES) {
-            connectionDetails = null;
-
-            console.log('Env var \'VCAP_SERVICES\' found, scanning for \'catalogue_database\' service binding');
-
-            for (let [key, value] of Object.entries(JSON.parse(process.env.VCAP_SERVICES))) {
-                try {
-                    binding = value.find(function(binding) {
-                        return 'catalogue_database' == binding.binding_name && binding.credentials;
-                    });
-
-                    if (!binding) {
-                        continue;
-                    }
-
-                    connectionDetails = binding.credentials;
-
-                    if (connectionDetails) {
-                        mongoURL = connectionDetails.uri;
-
-                        console.log('MongoDB URI for \'catalogue_database\' service binding found in \'VCAP_SERVICES\'');
-
-                        break;
-                    }
-                } catch (err) {
-                    console.log('Cannot process key \'' + key + '\' of \'VCAP_SERVICES\'', err);
-                    throw err;
-                }
-            }
-        } else if (process.env.MONGO_URL) {
-            mongoURL = process.env.MONGO_URL;
-
-            console.log('MongoDB URI found in \'MONGO_URL\': ' + mongoURL);
-        } else {
-            mongoURL = 'mongodb://mongodb:27017/catalogue';
-
-            console.log('Using default MongoDB URI');
-        }
-
-        if (!mongoURL) {
-            throw new Error('MongoDB connection data missing');
-        }
-
-        mongoClient.connect(mongoURL, (error, db) => {
-            if(error) {
-                reject(error);
-            } else {
-                productsCollection = db.collection('products');
-                resolve('connected');
-            }
-        });
-    });
-}
-
-// mongodb connection retry loop
-function mongoLoop() {
-    mongoConnect().then((r) => {
-        mongoConnected = true;
-        logger.info('MongoDB connected');
-    }).catch((e) => {
-        logger.error('An error occurred', e);
-        setTimeout(mongoLoop, 2000);
-    });
-}
-
-mongoLoop();
-
-// fire it up!
-const port = process.env.CATALOGUE_SERVER_PORT || '8080';
+// Fire up
 app.listen(port, () => {
     logger.info('Started on port', port);
 });
-
diff --git a/user/package-lock.json b/user/package-lock.json
new file mode 100644
index 0000000..4f79255
--- /dev/null
+++ b/user/package-lock.json
@@ -0,0 +1,63 @@
+{
+  "name": "user",
+  "version": "1.0.0",
+  "lockfileVersion": 1,
+  "requires": true,
+  "dependencies": {
+    "complex.js": {
+      "version": "2.0.11",
+      "resolved": "https://registry.npmjs.org/complex.js/-/complex.js-2.0.11.tgz",
+      "integrity": "sha512-6IArJLApNtdg1P1dFtn3dnyzoZBEF0MwMnrfF1exSBRpZYoy4yieMkpZhQDC0uwctw48vii0CFVyHfpgZ/DfGw=="
+    },
+    "decimal.js": {
+      "version": "10.2.0",
+      "resolved": "https://registry.npmjs.org/decimal.js/-/decimal.js-10.2.0.tgz",
+      "integrity": "sha512-vDPw+rDgn3bZe1+F/pyEwb1oMG2XTlRVgAa6B4KccTEpYgF8w6eQllVbQcfIJnZyvzFtFpxnpGtx8dd7DJp/Rw=="
+    },
+    "escape-latex": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/escape-latex/-/escape-latex-1.2.0.tgz",
+      "integrity": "sha512-nV5aVWW1K0wEiUIEdZ4erkGGH8mDxGyxSeqPzRNtWP7ataw+/olFObw7hujFWlVjNsaDFw5VZ5NzVSIqRgfTiw=="
+    },
+    "fraction.js": {
+      "version": "4.0.12",
+      "resolved": "https://registry.npmjs.org/fraction.js/-/fraction.js-4.0.12.tgz",
+      "integrity": "sha512-8Z1K0VTG4hzYY7kA/1sj4/r1/RWLBD3xwReT/RCrUCbzPszjNQCCsy3ktkU/eaEqX3MYa4pY37a52eiBlPMlhA=="
+    },
+    "javascript-natural-sort": {
+      "version": "0.7.1",
+      "resolved": "https://registry.npmjs.org/javascript-natural-sort/-/javascript-natural-sort-0.7.1.tgz",
+      "integrity": "sha1-+eIwPUUH9tdDVac2ZNFED7Wg71k="
+    },
+    "mathjs": {
+      "version": "6.6.4",
+      "resolved": "https://registry.npmjs.org/mathjs/-/mathjs-6.6.4.tgz",
+      "integrity": "sha512-fvmP89ujJbDAC8ths7FZh7PWdA71dfA5WJVAzJbQhSDCHK1aBk8WRf1XcTw51ERs+sKx9nYBGsRshqmb/oe8Ag==",
+      "requires": {
+        "complex.js": "^2.0.11",
+        "decimal.js": "^10.2.0",
+        "escape-latex": "^1.2.0",
+        "fraction.js": "^4.0.12",
+        "javascript-natural-sort": "^0.7.1",
+        "seed-random": "^2.2.0",
+        "tiny-emitter": "^2.1.0",
+        "typed-function": "^1.1.1"
+      }
+    },
+    "seed-random": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/seed-random/-/seed-random-2.2.0.tgz",
+      "integrity": "sha1-KpsZ4lCoFwmSMaW5mk2vgLf77VQ="
+    },
+    "tiny-emitter": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/tiny-emitter/-/tiny-emitter-2.1.0.tgz",
+      "integrity": "sha512-NB6Dk1A9xgQPMoGqC5CVXn123gWyte215ONT5Pp5a0yt4nlEoO1ZWeCwpncaekPHXO60i47ihFnZPiRPjRMq4Q=="
+    },
+    "typed-function": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/typed-function/-/typed-function-1.1.1.tgz",
+      "integrity": "sha512-RbN7MaTQBZLJYzDENHPA0nUmWT0Ex80KHItprrgbTPufYhIlTePvCXZxyQK7wgn19FW5bnuaBIKcBb5mRWjB1Q=="
+    }
+  }
+}
diff --git a/user/package.json b/user/package.json
index 577c8f2..0ba98d5 100644
--- a/user/package.json
+++ b/user/package.json
@@ -9,13 +9,14 @@
   "author": "SteveW",
   "license": "Apache-2.0",
   "dependencies": {
-      "body-parser": "^1.18.1",
-      "express": "^4.15.4",
-      "mongodb": "^2.2.33",
-      "redis": "^2.8.0",
-      "pino": "^5.10.8",
-      "express-pino-logger": "^4.0.0",
-      "pino-pretty": "^2.5.0",
-      "instana-nodejs-sensor": "^1.28.0"
+    "body-parser": "^1.18.1",
+    "express": "^4.15.4",
+    "express-pino-logger": "^4.0.0",
+    "instana-nodejs-sensor": "^1.28.0",
+    "mathjs": "^6.6.4",
+    "mongodb": "^2.2.33",
+    "pino": "^5.10.8",
+    "pino-pretty": "^2.5.0",
+    "redis": "^2.8.0"
   }
 }
diff --git a/user/server.js b/user/server.js
index 1fbd340..1ce3456 100644
--- a/user/server.js
+++ b/user/server.js
@@ -15,6 +15,10 @@ const bodyParser = require('body-parser');
 const express = require('express');
 const pino = require('pino');
 const expPino = require('express-pino-logger');
+const { randomInt } = require('mathjs');
+
+const errorRate = parseInt(process.env.ERROR_RATE) || 0
+
 
 // MongoDB
 var db;
@@ -55,6 +59,11 @@ app.get('/health', (req, res) => {
 
 // use REDIS INCR to track anonymous users
 app.get('/uniqueid', (req, res) => {
+    if (errorRate > randomInt(1, 100)) {
+        res.status(500).send('Cannot process the uniqueid request');
+        return;
+    }
+
     req.log.error('Unique ID test');
     // get number from Redis
     redisClient.incr('anonymous-counter', (err, r) => {
@@ -71,6 +80,11 @@ app.get('/uniqueid', (req, res) => {
 
 // check user exists
 app.get('/check/:id', (req, res) => {
+    if (errorRate > randomInt(1, 100)) {
+        res.status(500).send('Cannot process the check user request');
+        return;
+    }
+
     if(mongoConnected) {
         usersCollection.findOne({name: req.params.id}).then((user) => {
             if(user) {
@@ -104,6 +118,11 @@ app.get('/users', (req, res) => {
 });
 
 app.post('/login', (req, res) => {
+    if (errorRate > randomInt(1, 100)) {
+        res.status(500).send('Cannot process the login request');
+        return;
+    }
+
     req.log.info('login', req.body);
     if(req.body.name === undefined || req.body.password === undefined) {
         req.log.warn('credentails not complete');
@@ -134,6 +153,11 @@ app.post('/login', (req, res) => {
 
 // TODO - validate email address format
 app.post('/register', (req, res) => {
+    if (errorRate > randomInt(1, 100)) {
+        res.status(500).send('Cannot process the registration request');
+        return;
+    }
+
     req.log.info('register', req.body);
     if(req.body.name === undefined || req.body.password === undefined || req.body.email === undefined) {
         req.log.warn('insufficient data');
@@ -169,6 +193,11 @@ app.post('/register', (req, res) => {
 });
 
 app.post('/order/:id', (req, res) => {
+    if (errorRate > randomInt(1, 100)) {
+        res.status(500).send('Cannot process the order request');
+        return;
+    }
+
     req.log.info('order', req.body);
     // only for registered users
     if(mongoConnected) {
@@ -223,6 +252,11 @@ app.post('/order/:id', (req, res) => {
 });
 
 app.get('/history/:id', (req, res) => {
+    if (errorRate > randomInt(1, 100)) {
+        res.status(500).send('Cannot process the history request');
+        return;
+    }
+
     if(mongoConnected) {
         ordersCollection.findOne({
             name: req.params.id