diff --git a/backend/moleculer.js b/backend/moleculer.js
new file mode 100644
index 0000000..1ddc1ad
--- /dev/null
+++ b/backend/moleculer.js
@@ -0,0 +1,709 @@
+/* *******************************************************************************************
+ * MOLECULER MICROSERVICES FRAMEWORK - CORE CHEATSHEET
+ * http://moleculer.services/0.12/docs/
+ *
+ * Version: 0.12.x
+ * ******************************************************************************************* */
+
+/* *******************************************************************************************
+ * Install Moleculer
+ * ******************************************************************************************* */
+
+```bash
+npm i moleculer
+```
+
+/* *******************************************************************************************
+ * SERVICE BROKER OPTIONS
+ * ******************************************************************************************* */
+
+// All ServiceBroker options with default values
+const broker = new ServiceBroker({
+    namespace: "",                          // Namespace for node segmentation
+    nodeID: null,                           // NodeID. Default value is generated from hostname and PID
+
+    logger: null,                           // Logger instance.
+    logLevel: null,                         // Log level
+    logFormatter: "default",                // Log formatter. Options: "default", "simple"
+
+    transporter: null,                      // Transporter config
+    requestTimeout: 0 * 1000,               // Timeout of requests
+    requestRetry: 0,                        // Retries for requests
+    maxCallLevel: 0,                        // Maximum calling level.
+    heartbeatInterval: 5,                   // Heartbeat sending interval in seconds
+    heartbeatTimeout: 15,                   // Heartbeat timeout in seconds
+
+    disableBalancer: false,                 // Disable the built-in Moleculer balancer
+
+    registry: {                             // Service Registry options
+        strategy: "RoundRobin",             // Invocation strategy
+        strategyOptions: null,              // Strategy options
+        preferLocal: true                   // Prefer local invocations
+    },
+
+    circuitBreaker: {                       // Circuit-breaker options
+        enabled: false,                     // Enable circuit-breaker
+        maxFailures: 3,                     // Maximum failures
+        halfOpenTime: 10 * 1000,            // Half-open time interval
+        failureOnTimeout: true,             // Failure on timeouts
+        failureOnReject: true               // Failure on rejects
+    },
+
+    transit: {                              // Transit options
+        maxQueueSize: 50 * 1000             // Max items in outgoing queue
+    },
+
+    cacher: null,                           // Cacher config
+    serializer: null,                       // Serializer config
+
+    validation: true,                       // Enable params validation
+    validator: null,                        // Validator instance
+    metrics: false,                         // Enable metrics
+    metricsRate: 1,                         // Metrics rate
+    statistics: false,                      // Enable statistics
+    internalServices: true,                 // Load internal ($node) services
+
+    hotReload: false,                       // Hot-reload  services
+
+    middlewares: null,                      // List of middlewares
+
+    replCommands: null,                     // Custom REPL commands
+
+    ServiceFactory: null,                   // Custom Service factory class
+    ContextFactory: null                    // Custom Context factory class
+});
+
+/* *******************************************************************************************
+ * SERVICE BROKER METHODS
+ * ******************************************************************************************* */
+
+// Broker properties
+broker.Promise                                  // Pointer to Bluebird Promise lib
+broker.namespace                                // Namespace from options
+broker.nodeID                                   // Local NodeID
+broker.logger                                   // Logger instance
+broker.cacher                                   // Cacher instance
+broker.serializer                               // Serializer instance
+broker.validator                                // Validator instance
+
+// Broker methods
+broker.start();                                 // Start broker & all services. Returns a Promise
+broker.stop();                                  // Stop broker & all services. Returns a Promise
+broker.fatal(message, err, needExit = true);    // Fired a fatal error.
+broker.repl();                                  // Switch broker to REPL mode.
+
+broker.getLogger(module, service, version);     // Create a custom logger instance for modules
+
+broker.loadServices(folder, fileMask);          // Load all services from directory
+broker.loadService(filePath);                   // Load a service from a file
+broker.createService(schema, schemaMods);       // Create a local service from schema
+broker.destroyService(service);                 // Destroy a local service
+broker.getLocalService(name, version);          // Get a local service instance by name
+
+// Wait for services. Returns a Promise
+await broker.waitForServices(serviceNames, timeout, interval);
+await broker.waitForServices(["posts", "users"], 5000);
+await broker.waitForServices({
+    name: "posts", version: 2,
+    name: "users", version: 1
+}, 5000);
+
+broker.use(...middlewares);                     // Register middlewares
+
+broker.call(actionName, params, opts);          // Call a service
+broker.mcall(def);                              // Multiple service calls
+
+broker.emit(eventName, payload, groups);                    // Emit a balanced event
+broker.broadcast(eventName, payload, groups = null)         // Broadcast an event
+broker.broadcastLocal(eventName, payload, groups = null)    // Broadcast an event to local services
+
+broker.sendPing(nodeID);                        // Ping a remote node
+broker.MOLECULER_VERSION                        // Version number of Moleculer lib
+broker.PROTOCOL_VERSION                         // Version number of Moleculer protocol
+
+/* *******************************************************************************************
+ * BROKER SERVICE CALLS
+ * ******************************************************************************************* */
+
+// Call the "users.get" service with params
+broker.call("users.get", { id: 150 }).then(user => console.log(user));
+
+// Call with async/await
+const user = await broker.call("users.get", { id: 150});
+
+// Call with calling options
+const user = await broker.call("users.get", { id: 150}, { timeout: 5000, retryCount: 3 });
+
+// Direct call to a remote node
+const info = await broker.call("$node.services", null, { nodeID: "node-123" });
+
+// Multiple calls with array def
+const [posts, users] = await broker.mcall([
+    { action: "posts.find", params: { limit: 5, offset: 0 } },
+    { action: "users.find", params: { limit: 5, sort: "username" }, opts: { timeout: 500 } }
+]);
+
+// Multip calls with object def
+const res = await broker.mcall({
+    posts: { action: "posts.find", params: { limit: 5, offset: 0 } },
+    users: { action: "users.find", params: { limit: 5, sort: "username" }, opts: { timeout: 500 } }
+});
+console.log(res.posts, res.users);
+
+/* *******************************************************************************************
+ * BROKER EVENTS
+ * ******************************************************************************************* */
+
+// Send a balanced event with payload
+broker.emit("user.created", { user: user });
+
+// Send a balanced event only for "mail" and "payment" service (only one instance)
+broker.emit("user.created", { user: user }, ["mail", "payment"]);
+
+// Send a broadcast event (for all service instances)
+broker.broadcast("user.created", { user: user });
+
+// Send a broadcast event only for "mail" and "payment" services (all instances)
+broker.broadcast("user.created", { user: user }, ["mail", "payment"]);
+
+/* *******************************************************************************************
+ * NATS TRANSPORTER
+ * Requirement: `npm i nats`
+ * ******************************************************************************************* */
+
+// Default options
+const broker = new ServiceBroker({
+    transporter: "NATS"
+});
+
+// With URI
+const broker = new ServiceBroker({
+    transporter: "nats://localhost:4222"
+});
+
+// With options
+const broker = new ServiceBroker({
+    transporter: {
+        type: "NATS",
+        options: {
+            url: "nats://localhost:4222",
+            user: "admin",
+            pass: "1234"
+        }
+    }
+});
+
+// With TLS (https://github.com/nats-io/node-nats#tls)
+const broker = new ServiceBroker({
+    transporter: {
+        type: "NATS",
+        options: {
+            url: "nats://localhost:4222",
+            tls: {
+                key: fs.readFileSync('./client-key.pem'),
+                cert: fs.readFileSync('./client-cert.pem'),
+                ca: [ fs.readFileSync('./ca.pem') ]
+            }
+        }
+    }
+});
+
+/* *******************************************************************************************
+ * REDIS TRANSPORTER
+ * Requirement: `npm i ioredis`
+ * ******************************************************************************************* */
+
+// Default options
+const broker = new ServiceBroker({
+    transporter: "Redis"
+});
+
+// With URI
+const broker = new ServiceBroker({
+    transporter: "redis://redis-server:6379"
+});
+
+// With options
+const broker = new ServiceBroker({
+    transporter: {
+        type: "Redis",
+        options: {
+            port: 6379,             // Redis port
+            host: 'redis-server',   // Redis host
+            family: 4,              // 4 (IPv4) or 6 (IPv6)
+            password: 'auth',       // Password
+            db: 0                   // Database index
+        }
+    }
+});
+
+
+/* *******************************************************************************************
+ * MQTT TRANSPORTER
+ * Requirement: `npm i mqtt`
+ * ******************************************************************************************* */
+
+// Default options
+const broker = new ServiceBroker({
+    transporter: "MQTT"
+});
+
+// With URI
+const broker = new ServiceBroker({
+    transporter: "mqtt://mqtt-server:1883"
+});
+
+// With options
+const broker = new ServiceBroker({
+    transporter: {
+        type: "MQTT",
+        options: {
+            host: "mqtt-server",
+            port: 1883,
+            username: "admin",
+            password: "1234"
+        }
+    }
+});
+
+/* *******************************************************************************************
+ * AMQP TRANSPORTER
+ * Requirement: `npm i amqplib`
+ * ******************************************************************************************* */
+
+// Default options
+const broker = new ServiceBroker({
+    transporter: "AMQP"
+});
+
+// With URI
+const broker = new ServiceBroker({
+    transporter: "amqp://rabbitmq-server:5672"
+});
+
+// With options
+const broker = new ServiceBroker({
+    transporter: {
+        type: "AMQP",
+        options: {
+            url: "amqp://user:pass@rabbitmq-server:5672",
+            eventTimeToLive: 5000,
+            prefetch: 1
+        }
+    }
+});
+
+/* *******************************************************************************************
+ * KAFKA TRANSPORTER
+ * Requirement: `npm i kafka-node`
+ * ******************************************************************************************* */
+
+// Default options
+const broker = new ServiceBroker({
+    transporter: "Kafka"
+});
+
+// With URI
+const broker = new ServiceBroker({
+    transporter: "kafka://192.168.51.29:2181"
+});
+
+// With options
+const broker = new ServiceBroker({
+    transporter: {
+        type: "kafka",
+        options: {
+            host: "192.168.51.29:2181",
+
+            // KafkaClient options. More info: https://github.com/SOHU-Co/kafka-node#clientconnectionstring-clientid-zkoptions-noackbatchoptions-ssloptions
+            client: {
+                zkOptions: undefined,
+                noAckBatchOptions: undefined,
+                sslOptions: undefined
+            },
+
+            // KafkaProducer options. More info: https://github.com/SOHU-Co/kafka-node#producerclient-options-custompartitioner
+            producer: {},
+            customPartitioner: undefined,
+
+            // ConsumerGroup options. More info: https://github.com/SOHU-Co/kafka-node#consumergroupoptions-topics
+            consumer: {
+            },
+
+            // Advanced options for `send`. More info: https://github.com/SOHU-Co/kafka-node#sendpayloads-cb
+            publish: {
+                partition: 0,
+                attributes: 0
+            }
+        }
+    }
+});
+
+/* *******************************************************************************************
+ * NATS STREAMING TRANSPORTER
+ * Requirement: `npm i node-nats-streaming`
+ * ******************************************************************************************* */
+
+// Default options
+const broker = new ServiceBroker({
+    transporter: "STAN"
+});
+
+// With URI
+const broker = new ServiceBroker({
+    transporter: "stan://192.168.0.120:4222"
+});
+
+// With options
+const broker = new ServiceBroker({
+    transporter: {
+        type: "STAN",
+        options: {
+            url: "stan://127.0.0.1:4222",
+            clusterID: "my-cluster"
+        }
+    }
+});
+
+/* *******************************************************************************************
+ * TCP STREAMING TRANSPORTER
+ * No requirements
+ * ******************************************************************************************* */
+
+// Default options
+const broker = new ServiceBroker({
+    transporter: "TCP"
+});
+
+// With static node list
+const broker = new ServiceBroker({
+    transporter: "tcp://172.17.0.1:6000/node-1,172.17.0.2:6000/node-2"
+});
+
+const broker = new ServiceBroker({
+    nodeID: "node-1",
+    transporter: {
+        type: "TCP",
+        options: {
+            udpDiscovery: false,
+            urls: [
+                "172.17.0.1:6000/node-1",
+                "172.17.0.2:6000/node-2",
+                "172.17.0.3:6000/node-3"
+            ]
+        }
+    }
+});
+
+// With full options
+const broker = new ServiceBroker({
+    logger: true,
+    transporter: {
+        type: "TCP",
+        options: {
+            // Enable UDP discovery
+            udpDiscovery: true,
+            // Reusing UDP server socket
+            udpReuseAddr: true,
+
+            // UDP port
+            udpPort: 4445,
+            // UDP bind address
+            udpBindAddress: null,
+            // UDP sending period
+            udpPeriod: 5,
+
+            // Multicast address.
+            udpMulticast: "239.0.0.0",
+            // Multicast TTL setting
+            udpMulticastTTL: 1,
+
+            // Send broadcast
+            udpBroadcast: false,
+
+            // TCP server port. Null or 0 means random port
+            port: null,
+            // Static remote nodes address list (when UDP discovery is not available)
+            urls: null,
+            // Use hostname as preffered connection address
+            useHostname: true,
+
+            // Gossip sending period in seconds
+            gossipPeriod: 2,
+            // Maximum enabled outgoing connections. If reach, close the old connections
+            maxConnections: 32,
+            // Maximum TCP packet size
+            maxPacketSize: 1 * 1024 * 1024
+        }
+    }
+});
+
+
+/* *******************************************************************************************
+ * CACHERS
+ * http://moleculer.services/docs/cachers.html
+ * ******************************************************************************************* */
+
+// Memory cacher
+const broker = new ServiceBroker({
+    cacher: "Memory"
+});
+// or
+const broker = new ServiceBroker({
+    cacher: true
+});
+
+// Memory cacher with options
+const broker = new ServiceBroker({
+    cacher: {
+        type: "Memory",
+        options: {
+            ttl: 30
+        }
+    }
+});
+
+// Redis cacher
+const broker = new ServiceBroker({
+    cacher: "Redis"
+});
+
+// Redis cacher with URI
+const broker = new ServiceBroker({
+    cacher: "redis://redis-server:6379"
+});
+
+// Redis cacher with options
+const broker = new ServiceBroker({
+    cacher: {
+        type: "Redis",
+        options: {
+            prefix: "MOL",
+            redis: {
+                host: "redis",
+                port: 6379,
+                password: "1234",
+                db: 0
+            }
+        }
+    }
+});
+
+/* *******************************************************************************************
+ * Manual caching
+ * ******************************************************************************************* */
+
+// Save to cache
+broker.cacher.set("mykey.a", { a: 5 });
+
+// Get from cache
+const obj = await broker.cacher.get("mykey.a");
+
+// Remove entry from cache
+broker.cacher.del("mykey.a");
+
+// Clean all 'mykey' entries
+broker.cacher.clean("mykey.*");
+
+// Clean all entries
+broker.cacher.clean();
+
+/* *******************************************************************************************
+ * SERIALIZER
+ * http://moleculer.services/docs/serializers.html
+ * ******************************************************************************************* */
+
+// JSON serializer (default)
+const broker = new ServiceBroker({
+    serializer: "JSON"
+});
+
+// Avro serializer (need `npm i avsc`)
+const broker = new ServiceBroker({
+    serializer: "Avro"
+});
+
+// Protocol Buffer serializer (need `npm i protobufjs`)
+const broker = new ServiceBroker({
+    serializer: "ProtoBuf"
+});
+
+// MsgPack serializer (need `npm i msgpack5`)
+const broker = new ServiceBroker({
+    serializer: "MsgPack"
+});
+
+/* *******************************************************************************************
+ * STRATEGY
+ * ******************************************************************************************* */
+
+// Round-robin strategy (default)
+const broker = new ServiceBroker({
+    registry: {
+        strategy: "RoundRobin"
+    }
+});
+
+// Random strategy
+const broker = new ServiceBroker({
+    registry: {
+        strategy: "Random"
+    }
+});
+
+// CPU usage-based strategy
+const broker = new ServiceBroker({
+    registry: {
+        strategy: "CpuUsageStrategy"
+    }
+});
+
+// CPU usage-based strategy with options
+const broker = new ServiceBroker({
+    registry: {
+        strategy: "CpuUsageStrategy",
+        strategyOptions: {
+            sampleCount: 3,
+            lowCpuUsage: 10
+        }
+    }
+});
+
+/* *******************************************************************************************
+ * LOGGER
+ * http://moleculer.services/docs/logger.html
+ * ******************************************************************************************* */
+
+// Logger methods
+broker.logger.fatal();
+broker.logger.error();
+broker.logger.warn();
+broker.logger.info();
+broker.logger.debug();
+broker.logger.trace();
+
+// Custom log formatter
+const broker = new ServiceBroker({
+    logger: console,
+    logFormatter(level, args, bindings) {
+        return level.toUpperCase() + " " + bindings.nodeID + ": " + args.join(" ");
+    }
+});
+
+// External Pino logger
+const pino = require("pino")({ level: "info" });
+const broker = new ServiceBroker({
+    logger: bindings => pino.child(bindings)
+});
+
+// External Bunyan logger
+const logger = require("bunyan").createLogger({ name: "moleculer", level: "info" });
+const broker = new ServiceBroker({
+    logger: bindings => logger.child(bindings)
+});
+
+/* *******************************************************************************************
+ * SERVICE SCHEMA
+ * ******************************************************************************************* */
+
+module.exports = {
+    // Name
+    name: "greeter",
+    // Version
+    version: 2,
+
+    // Settings
+    settings: {},
+    // Metadata
+    metadata: {},
+    // Dependencies
+    dependencies: [],
+
+    // Actions
+    actions: {
+        // Shorthand actions
+        hello() {
+            // Call a method
+            this.doSomething();
+
+            return "Hello Moleculer";
+        },
+
+        // With properties
+        welcome: {
+            // Cache options
+            cache: {
+                keys: ["name"]
+            },
+            // Validation options
+            params: {
+                name: "string"
+            },
+            // Action handler
+            handler(ctx) {
+                return `Welcome, ${ctx.params.name}`;
+            }
+        }
+    },
+
+    events: {
+        "user.created"(payload, sender) {
+
+        }
+    },
+
+    // Service methods
+    methods: {
+        doSomething() {}
+    },
+
+    // Lifecycle event handlers
+    created() {
+        console.log("Service created");
+    },
+
+    started() {
+        console.log("Service started");
+        return Promise.resolve();
+    },
+
+    stopped() {
+        console.log("Service stopped");
+        return Promise.resolve();
+    }
+};
+
+/* *******************************************************************************************
+ * SERVICE
+ * ******************************************************************************************* */
+
+this.name               // Name of service
+this.version            // Version of service
+this.settings           // Settings of service
+this.schema             // Schema definition of service
+this.broker             // Broker instance
+this.Promise            // Class of Promise (Bluebird)
+this.logger             // Logger instance
+this.actions            // Actions of service.
+this.waitForServices    // Pointer to ‘broker.waitForServices’ method
+
+/* *******************************************************************************************
+ * CONTEXT
+ * ******************************************************************************************* */
+
+ctx.id                  // Context ID
+ctx.broker              // Broker instance
+ctx.action              // Action definition
+ctx.nodeID              // Node ID
+ctx.requestID           // Request ID
+ctx.parentID            // ID of parent context (in case of sub-calls).
+ctx.params              // Request params
+ctx.meta                // Request metadata
+ctx.callerNodeID        // Caller Node ID if it is requested from a remote node.
+ctx.level               // Request level (in case of sub-calls). The first level is 1.
+
+// Make a sub-call
+ctx.call(actionName, params, callingOptions)
+
+// Emit an event
+ctx.emit(eventName, payload, groups);