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Last pushed: a year ago
Short Description
IoT Agent for a generic JSON protocol with MQTT transport.
Full Description



<a name="overview"/> Overview

This IoT Agent is designed to be a bridge between an MQTT+JSON based protocol and the OMA NGSI standard used in FIWARE.
This project is based in the Node.js IoT Agent library. More information about the IoT Agents can be found in its
Github page.

A quick way to get started is to read the Step by step guide.

If you want to contribute to the project, check out the Development section and the Contribution guidelines.

<a name="installation"/> Installation

There are two ways of installing the MQTT IoT Agent: using Git or RPMs.

Using GIT

In order to install the TT Agent, just clone the project and install the dependencies:

git clone
npm install

In order to start the IoT Agent, from the root folder of the project, type:


Using RPM

The project contains a script for generating an RPM that can be installed in Red Hat 6.5 compatible Linux distributions.
The RPM depends on Node.js 0.10 version, so EPEL repositories are advisable.

In order to create the RPM, execute the following scritp, inside the /rpm folder: -v <versionNumber> -r <releaseNumber>

Once the RPM is generated, it can be installed using the followogin command:

yum localinstall --nogpg <nameOfTheRPM>.rpm

The IoTA will then be installed as a linux service, and can ve started with the service command as usual:

service iotaMQTT start

<a name="usage"/> Usage

In order to execute the MQTT IoT Agent just execute the following command from the root folder:


This will start the MQTT IoT Agent in the foreground. Use standard linux commands to start it in background.

When started with no arguments, the IoT Agent will expect to find a config.js file with the configuration in the root
folder. An argument can be passed with the path to a new configuration file (relative to the application folder) to be
used instead of the default one.

<a name="configuration"/> Configuration


All the configuration for the IoT Agent is stored in a single configuration file (typically installed in the root folder).

This configuration file is a JavaScript file and contains two configuration chapters:

  • iota: this object stores the configuration of the Northbound of the IoT Agent, and is completely managed by the
    IoT Agent library. More information about this options can be found here.
  • mqtt: this object stores MQTT's specific configuration. A detailed description can be found in the next section.

MQTT configuration

These are the currently available MQTT configuration options:

  • host: host of the MQTT broker.
  • port: port where the MQTT broker is listening.
  • defaultKey: default API Key to use when a device is provisioned without a configuration.
  • username: user name that identifies the IOTA against the MQTT broker (optional).
  • password: password to be used if the username is provided (optional).

<a name="protocol"/> Protocol


The MQTT-JSON protocol uses plain JSON objects to send information formatted as key-value maps over an MQTT transport.
It uses different topics to separate the different destinations and types of the messages (the different possible interactions
are described in the following sections).

All the topics used in the protocol are prefixed with the APIKey of the device group and the Device ID of the device
involved in the interaction; i.e.: there is a different set of topics for each service (e.g: /FF957A98/MyDeviceId/attributes).
The API Key is a secret identifier shared among all the devices of a service, and the DeviceID is an ID that uniquely
identifies the device in a service. API Keys can be configured with the IoTA Configuration API or the public default
API Key of the IoT Agent can be used in its stead. The Device ID must be provisioned in advance in the IoT Agent before
information is sent.

Along this document we will refer some times to "plain JSON objects" or "single-level JSON objects". With that, we mean:

  • valid JSON objects serialized as unescaped strings.
  • JSON objects with a single level, i.e.: all the first level attributes of the JSON object are Strings or Numbers (not
    arrays or other objects).

Measure reporting

There are two ways of reporting measures:

  • Multiple measures: In order to send multiple measures, a device can publish a JSON payload to an MQTT topic with the
    following structure:


    The message in this case must contain a valid JSON object of a single level; for each key/value pair, the key represents
    the attribute name and the value the attribute value. Attribute type will be taken from the device provision information.

  • Single measures: In order to send single measures, a device can publish the direct value to an MQTT topic with
    the following structure:


    Indicating in the topic the name of the attribute to be modified.

In both cases, the key is the one provisioned in the IOTA through the Configuration API, and the Device ID the ID that
was provisioned using the Provisioning API. API Key MUST be present, although can be any string in case the Device was
provisioned without a link to any particular configuration.

Value conversion

The IoTA performs some ad-hoc conversion for specific types of values, in order to minimize the parsing logic in the
device. This section lists those conversions.

Timestamp compression

Any attribute coming to the IoTA with the "timeInstant" name will be expected to be a timestamp in ISO8601 complete basic
calendar representation (e.g.: 20071103T131805). The IoT Agent will automatically transform this values to the extended
representation (e.g.: +002007-11-03T13:18:05) for any interaction with the Context Broker (updates and queries).

Thinking Things plugin

This IoT Agent retains some features from the Thinking Things Protocol IoT Agent to ease the transition from one protocol
to the other. This features are built in a plugin, that can be activated using the mqtt.thinkingThingsPlugin flag.
When the plugin is activated, the following rules apply to all the incoming MQTT-JSON requests:

  • If an attribute named P1 is found, its content will be parsed as a Phone Cell position, as described here.
  • If an attribute named C1 is found, its content will be parsed as if they would be a P1 attribute, but with all its
    fields codified in hexadecimal with a fixed 4 character length, without comma separation.
  • If an attribute named B is found, its content will be parsed as if they would be Battery information as described
    here. This implementation admits also an extended version
    of this attribute, adding the "batteryType" and "percentage" fields to the entity.

Configuration retrieval

The protocol offers a mechanism for the devices to retrieve its configuration (or any other value it needs from those
stored in the Context Broker). Two topics are created in order to support this feature: a topic for configuration
commands and a topic to receive configuration information.

Configuration command topic


The IoT Agent listens in this topic for requests coming from the device. The messages must contain a JSON document
with the following attributes:

  • type: indicates the type of command the device is sending. See below for accepted values.
  • fields: array with the names of the values to be retrieved from the Context Broker entity representing the device.

This command will trigger a query to the CB that will, as a result, end up with a new message posted to the Configuration
information topic (described bellow).


  "type": "configuration",
  "fields": [

There are two accepted values for the configuration command types:

  • subscription: this command will generate a subscription in the Context Broker that will be triggered whenever any of
    the selected values change. In case the value has changed, all the attributes will be retrieved.
  • configuration: this commands will generate a single request to the Context Broker from the IoTAgent, that will trigger
    a single publish message in the values topic.

Configuration information topic


Every device must subscribe to this topic, so it can receive configuration information. Whenever the device requests any
information from the IoTA, the information will be posted in this topic. The information is published in the same format
used in multiple measure reporting: a plain JSON with an attribute per value requested. An aditional parameter called
dt is added with the system current time.


  "sleepTime": "200",
  "warningLevel": "80",
  "dt": "20160125T092703Z"

<a name="client"/> Command Line Client

The MQTT IoT Agent comes with a client that can be used to test its features, simulating a device. The client can be
executed with the following command:


This will show a prompt where commands can be issued to the MQTT broker. For a list of the currently available commands
type help.

The client loads a global configuration used for all the commands, containing the host and port of the MQTT broker and
the API Key and Device ID of the device to simulate. This information can be changed with the config command.

In order to use any of the MQTT commands, you have to connect to the MQTT broker first. If no connection is available,
MQTT commands will show an error message reminding you to connect.

The Command Line Client gets its default values from a config file in the root of the project: client-config.js. This
config file can be used to permanently tune the MQTT broker parameters, or the default device ID and APIKey.

<a name="development"/> Development documentation


All contributions to this project are welcome. Developers planning to contribute should follow the Contribution Guidelines

Project build

The project is managed using Grunt Task Runner.

For a list of available task, type

grunt --help

The following sections show the available options in detail.


Mocha Test Runner + Chai Assertion Library + Sinon Spies, stubs.

The test environment is preconfigured to run BDD testing style with
chai.expect and chai.should() available globally while executing tests, as well as the Sinon-Chai plugin.

Module mocking during testing can be done with proxyquire


All the tests are designed to test end to end scenarios, and there are some requirements for its current execution:

  • Mosquitto v1.3.5 server running
  • MongoDB v3.x server running


To run tests, type

grunt test

Tests reports can be used together with Jenkins to monitor project quality metrics by means of TAP or XUnit plugins.
To generate TAP report in report/test/unit_tests.tap, type

grunt test-report

Coding guidelines

jshint, gjslint

Uses provided .jshintrc and .gjslintrc flag files. The latter requires Python and its use can be disabled
while creating the project skeleton with grunt-init.
To check source code style, type

grunt lint

Checkstyle reports can be used together with Jenkins to monitor project quality metrics by means of Checkstyle
and Violations plugins.
To generate Checkstyle and JSLint reports under report/lint/, type

grunt lint-report

Continuous testing

Support for continuous testing by modifying a src file or a test.
For continuous testing, type

grunt watch

Source Code documentation


Generates HTML documentation under site/doc/. It can be used together with jenkins by means of DocLinks plugin.
For compiling source code documentation, type

grunt doc

Code Coverage


Analizes the code coverage of your tests.

To generate an HTML coverage report under site/coverage/ and to print out a summary, type

# Use git-bash on Windows
grunt coverage

To generate a Cobertura report in report/coverage/cobertura-coverage.xml that can be used together with Jenkins to
monitor project quality metrics by means of Cobertura plugin, type

# Use git-bash on Windows
grunt coverage-report

Code complexity


Analizes code complexity using Plato and stores the report under site/report/. It can be used together with jenkins
by means of DocLinks plugin.
For complexity report, type

grunt complexity


Update the contributors for the project

grunt contributors

Development environment

Initialize your environment with git hooks.

grunt init-dev-env

We strongly suggest you to make an automatic execution of this task for every developer simply by adding the following
lines to your package.json

  "scripts": {
     "postinstall": "grunt init-dev-env"

Site generation

There is a grunt task to generate the GitHub pages of the project, publishing also coverage, complexity and JSDocs pages.
In order to initialize the GitHub pages, use:

grunt init-pages

This will also create a site folder under the root of your repository. This site folder is detached from your repository's
history, and associated to the gh-pages branch, created for publishing. This initialization action should be done only
once in the project history. Once the site has been initialized, publish with the following command:

grunt site

This command will only work after the developer has executed init-dev-env (that's the goal that will create the detached site).

This command will also launch the coverage, doc and complexity task (see in the above sections).

Docker Pull Command
Source Repository

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