Add IoTHub writer module and update the documentation.

.editorconfig

@@ -0,0 +1,23 @@
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+# Matches multiple files with brace expansion notation
+# Set default charset
+[*]
+charset = utf-8
+
+# 2 space indentation
+[*]
+indent_style = space
+indent_size = 2
+
+# Tab indentation (no size specified)
+[*]
+indent_style = space
+
+

.gitattributes

@@ -15,6 +15,7 @@
 *.npmrc text eol=lf
 .gitattributes text eol=lf
 .gitignore text eol=lf
+.editorconfig eol=lf
 
 
 # Denote all files that are truly binary and should not be modified.

README.md

@@ -9,4 +9,5 @@ This is a simple tutorial shows Javascript developer how to setup module develop
 1. `git clone https://github.com/Azure-Samples/azure-iot-gateway-samples.git`
 2. `cd azure-iot-gateway-samples/js`
 3. `npm install` to install pre-built core runtime of gateway.
-4. `npm start` to start the gateway with pre-defined modules(sensor and printer).
+4. `npm run local` to start the gateway with pre-defined modules(sensor and printer).
+

js/README.md

@@ -1,16 +1,41 @@
 # Simple Gateway Modules
 This sample simply shows:
-- How to write modules(sensor.js, printer.js) in Javascript.
-- How to custmize the gateway runtime(gw.config.json).
-- How to initialize and start the gateway application in Javascript(index.js).
+- How to write modules(sensor.js, printer.js, iothub_writer.js) in Javascript.
+- How to custmize the gateway runtime(gw.[local|cloud].config.json).
+- How to initialize and start the gateway application in Javascript(app.js).
 
 # Technical Details
 ## Callbacks
-Each module(sensor/printer) needs to implement callbacks for different events:
+Each module(sensor/printer/iothub_writer) needs to implement callbacks for different events:
 1. create - module is created.
 2. start - module starts.
 3. receive - receive message from broker.
 4. destroy - modules is destroyed.
 ## Data pipeline
-The configuration JSON file(gw.config.json) to initialize each gateway instance will need to define 
-the data links for different module pair<sensor, printer>.
+The configuration JSON file(gw.[local|cloud].config.json) to initialize each gateway instance will 
+need to define the data links for different module pairs.
+## Connect to Azure IoT Hub
+iothub_writer module shows you how to establish connection between gateway application and azure iot
+hub. Below are the steps to configure and run it:
+1. Go to [Azure IoT Hub portal](https://azure.microsoft.com/en-us/services/iot-hub/) to create an 
+IoT hub instance with your own Azure subscription account to connecte your gateway application.
+2. Update `gw.cloud.config.json` by replacing `<IoT Hub device connection string>` (in the 
+`iothub_writer` module config JSON (*shown below*)) with your actual IoT Hub device connection
+string
+```
+  {
+    "name": "iothub_writer",
+    "loader": {
+      "name": "node",
+      "entrypoint": {
+        "main.path": "modules/iothub_writer.js"
+      }
+    },
+    "args": {
+      "connection_string": "<IoT Hub device connection string>"
+    }
+  }
+```
+3. `cd modules & npm install`
+4. `cd .. & npm install`
+5. `npm run cloud`

js/app.js

@@ -0,0 +1,24 @@
+(function() {
+  'use strict';
+
+  const Gateway = require('azure-iot-gateway');
+  let config_path = null;
+
+  // node app.js [local | cloud ]
+  if (process.argv.length < 3) {
+    throw 'Calling pattern should be node app.js [local | cloud].';
+  }
+
+  const option = process.argv[2];
+
+  if (option === 'local') {
+    config_path = './gw.local.config.json';
+  } else if (option === 'cloud') {
+    config_path = './gw.cloud.config.json';
+  } else {
+    throw 'Invalid option to start app.js !';
+  }
+
+  const gw = new Gateway(config_path);
+  gw.run();
+})();

js/gw.cloud.config.json

@@ -0,0 +1,34 @@
+{
+  "loaders": [{
+    "type": "node",
+    "name": "node"
+  }],
+  "modules": [{
+      "name": "node_sensor",
+      "loader": {
+        "name": "node",
+        "entrypoint": {
+          "main.path": "modules/sensor.js"
+        }
+      },
+      "args": null
+    },
+    {
+      "name": "iothub_writer",
+      "loader": {
+        "name": "node",
+        "entrypoint": {
+          "main.path": "modules/iothub_writer.js"
+        }
+      },
+      "args": {
+        "connection_string": "<IoT Hub device connection string>"
+      }
+    }
+  ],
+  "links": [{
+      "source": "node_sensor",
+      "sink": "node_printer"
+    }
+  ]
+}

js/gw.config.json → js/gw.local.config.json

@@ -1,12 +1,9 @@
 {
-  "loaders": [
-    {
-      "type": "node",
-      "name": "node"
-    }
-  ],
-  "modules": [
-    {
+  "loaders": [{
+    "type": "node",
+    "name": "node"
+  }],
+  "modules": [{
       "name": "node_printer",
       "loader": {
         "name": "node",
@@ -27,8 +24,7 @@
       "args": null
     }
   ],
-  "links": [
-    {
+  "links": [{
       "source": "node_sensor",
       "sink": "node_printer"
     }

js/modules/iothub_writer.js

@@ -0,0 +1,77 @@
+'use strict';
+
+let Protocol = require('azure-iot-device-amqp').Amqp;
+let Client = require('azure-iot-device').Client;
+let Message = require('azure-iot-device').Message;
+
+class IotHubWriterModule {
+  constructor() {
+    this.iothub_client = null;
+    this.connected = false;
+  }
+
+  on_connect(err) {
+    if (err) {
+      console.error(`Could not connect to IoT Hub. Error: ${err.message}`);
+    } else {
+      this.connected = true;
+      this.iothub_client.on('error', this.on_error.bind(this));
+      this.iothub_client.on('disconnect', this.on_disconnect.bind(this));
+    }
+  }
+
+  on_error(err) {
+    console.error(`Azure IoT Hub error: ${err.message}`);
+  }
+
+  on_disconnect() {
+    console.log('Got disconnected from Azure IoT Hub.');
+    this.connected = false;
+  }
+
+  create(broker, configuration) {
+    this.broker = broker;
+    this.configuration = configuration;
+
+    if (this.configuration && this.configuration.connection_string) {
+      // open a connection to the IoT Hub
+      this.iothub_client = Client.fromConnectionString(this.configuration.connection_string, Protocol);
+      this.iothub_client.open(this.on_connect.bind(this));
+
+      return true;
+    } else {
+      console.error('This module requires the connection string to be passed in via configuration.');
+      return false;
+    }
+  }
+
+  receive(message) {
+    if (this.connected) {
+      var m = new Message(message.content ? message.content.buffer : []);
+      if (message.properties) {
+        for (var prop in message.properties) {
+          m.properties.add(prop, message.properties[prop]);
+        }
+      }
+
+      this.iothub_client.sendEvent(m, err => {
+        if (err) {
+          console.error(`An error occurred when sending message to Azure IoT Hub: ${err.toString()}`);
+        }
+      });
+    }
+  }
+
+  destroy() {
+    console.log('iothub_writer.destroy');
+    if (this.connected) {
+      this.iothub_client.close(err => {
+        if (err) {
+          console.error(`An error occurred when disconnecting from Azure IoT Hub: ${err.toString()}`);
+        }
+      });
+    }
+  }
+}
+
+module.exports = new IotHubWriterModule();

js/modules/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "azure-iot-gateway-samples",
+  "version": "0.1.0",
+  "description": "",
+  "main": "iothub_writer.js",
+  "author": "Microsoft",
+  "license": "MIT",
+  "dependencies": {
+    "azure-iot-device": "^1.0.6",
+    "azure-iot-device-amqp": "^1.0.6"
+  }
+}

js/package.json

@@ -6,9 +6,10 @@
     "type": "git",
     "url": "https://github.com/Azure-Samples/azure-iot-gateway-sample"
   },
-  "main": "index.js",
+  "main": "app.js",
   "scripts": {
-    "start": "node index.js"
+    "local": "node app.js local",
+    "cloud": "node app.js cloud"
   },
   "author": "Microsoft Corporation",
   "license": "MIT",