Sparkplug Client

A client library providing a MQTT client for MQTT device communication using the Sparkplug Specification from Cirrus Link Solutions.

https://s3.amazonaws.com/ignition-modules/Current/Sparkplug+Specification.pdf

The client will connect to an MQTT Server and act as an MQTT Edge of Network (EoN) Node. It will publish birth certificates (NBIRTH), node data messages (NDATA), and process node command messages (NCMD) that have been sent from another MQTT client.

The client also provides and interface for MQTT Device application code to publish device birth certificates (DBIRTH), device data messages (DDATA), device death certificates (DDEATH), and receive device command messages (DCMD) that have been sent from another MQTT client.

Installation

npm install sparkplug-client

Usage

Creating and configuring a new Sparkplug client

A configuration object is required when creating a new client. A configuration must contain the following properties:

• serverUrl: The URL of the MQTT server.
• username: The username for the MQTT server connection.
• password: The password for the MQTT server connection.
• groupId: An ID representing a logical grouping of MQTT EoN Nodes and Devices into the infrastructure.
• edgeNode: An ID that uniquely identifies the MQTT EoN Node within the infrastructure.
• clientId: A unique ID for the MQTT client connection.
• publishDeath: A flag indicating if a Node DEATH Certificate (NDEATH) should be published when the client is stopped (defaults to false).
• version: The Sparkplug version (currently: A or B). This will indicate how the payload of the published Sparkplug messages are formatted.
• keepalive: The MQTT client keep alive interval in seconds (defaults to 30).

Here is a code example of creating and configuring a new client:

var sparkplug = require('sparkplug-client'),
    config = {
        'serverUrl' : 'tcp://localhost:1883',
        'username' : 'username',
        'password' : 'password',
        'groupId' : 'Sparkplug Devices',
        'edgeNode' : 'Test Edge Node',
        'clientId' : 'JavaScriptSimpleEdgeNode',
        'version' : 'spBv1.0'
    },
    client = sparkplug.newClient(config);

Stopping the client

Once a client has been created and configured it will automatically connect to the MQTT Server. the client provides a function for stopping the client and cleanly disconnecting from the MQTT Server. Once a client has been stopped, a new client must be created and configured in order to re-establish a connection with the server.

Here is a code example of stopping a client:

// Stop the sparkplug client
client.stop();

Publishing messages

This client provides functions for publishing three types of messages: a device birth certificate (DBIRTH), device data message (DDATA), device death certificate (DDEATH)

Message Payloads

The payload format for Sparkplug messages differs based on the Sparkplug version. A full description of each versions payload format is beyond the scope of this readme and can be found in the Sparkplug specification linked above. The examples in this readme will be using Sparkplug B.

Here is a quick summary of the main changes in version B (over A):

• Added more supported data types for metric values
• Added support for generic property sets
• Removed required "position" field
• Change the name of the metrics list field from "metric" to "metrics".

Publish Options

Each of the publish methods below can optionally take an object as an additional argument. This object contains any configured options for the publish.

Compression Option

A payload can be compressed before it is published by enabling payload compression in the options object and passing it to a plush command. For example:

var options = {
    "compress" : true
};

// Publish device data
client.publishDeviceData(deviceId, payload, options);

Additionally the compression algorithm can be specified as well. Currently supported algorithms are: DEFLATE and GZIP. DEFLATE will be used if not algorithm is specified. For example:

var options = {
    "compress" : true,
    "algorithm" : "GZIP"
};

// Publish device data
client.publishDeviceData(deviceId, payload, options);

Edge Node Birth Certificate (NBIRTH)

A Sparkplug node birth certificate (NBIRTH) message will contain all data points, process variables, and/or metrics for the edge node. The payload for this message will differ slightly between the different Sparkplug versions.

• timestamp: A UTC timestamp represented by 64 bit integer.
• metrics: An array of metric objects. Each metric in the array must contain the following:
  • name: The name of the metric.
  • value: The value of the metric.
  • type: The type of the metric. The following types are supported: int, int8, int16, int32, int64, uint8, uint16, uint32, uint64, float, double, boolean, string, datetime, text, uuid, dataset, bytes, file, or template.

Here is a code example of publishing a NBIRTH message:

var payload = {
        "timestamp" : 1465577611580,
        "metrics" : [
            {
                "name" : "my_int",
                "value" : 456,
                "type" : "Int32"
            },
            {
                "name" : "my_float",
                "value" : 1.23,
                "type" : "Float"
            }
        ]
    };

// Publish device birth
client.publishNodeBirth(payload);

Device Birth Certificate (DBIRTH)

A Sparkplug device birth certificate (DBIRTH) message will contain all data points, process variables, and/or metrics for the device. The payload for this message will differ slightly between the different Sparkplug versions.

• timestamp: A UTC timestamp represented by 64 bit integer.
• metrics: An array of metric objects. Each metric in the array must contain the following:
  • name: The name of the metric.
  • value: The value of the metric.
  • type: The type of the metric. The following types are supported: int, int8, int16, int32, int64, uint8, uint16, uint32, uint64, float, double, boolean, string, datetime, text, uuid, dataset, bytes, file, or template.

Here is a code example of publishing a DBIRTH message:

var deviceId = "testDevice",
    payload = {
        "timestamp" : 1465577611580,
        "metrics" : [
            {
                "name" : "my_int",
                "value" : 456,
                "type" : "Int32"
            },
            {
                "name" : "my_float",
                "value" : 1.23,
                "type" : "Float"
            }
        ]
    };

// Publish device birth
client.publishDeviceBirth(deviceId, payload);

Node Data Message (NDATA)

An edge node data message (NDATA) will look similar to NBIRTH but is not required to publish all metrics. However, it must publish at least one metric.

Here is a code example of publishing a DBIRTH message:

var payload = {
        "timestamp" : 1465456711580,
        "metrics" : [
            {
                "name" : "my_int",
                "value" : 412,
                "type" : "Int32"
            }
        ]
    };

// Publish device data
client.publishNodeData(payload);

Device Data Message (DDATA)

A device data message (DDATA) will look similar to DBIRTH but is not required to publish all metrics. However, it must publish at least one metric.

Here is a code example of publishing a DBIRTH message:

var deviceId = "testDevice",
    payload = {
        "timestamp" : 1465456711580,
        "metrics" : [
            {
                "name" : "my_int",
                "value" : 412,
                "type" : "Int32"
            }
        ]
    };

// Publish device data
client.publishDeviceData(deviceId, payload);

Node Death Certificate (NDEATH)

An edge node death certificate (NDEATH) is published to indicated that the edge node has gone offline or has lost a connection. It registered as an MQTT LWT by the SparkplugClient instance and published on the applications behalf.

Device Death Certificate (DDEATH)

A device death certificate (DDEATH) can be published to indicated that the device has gone offline or has lost a connection. It should contain only a timestamp.

Here is a code example of publishing a DDEATH message:

var deviceId = "testDevice",
    payload = {
        "timestamp" : 1465456711580
    };

// Publish device death
client.publishDeviceDeath(deviceId, payload);

Receiving events

The client uses an EventEmitter to emit events to device applications. The client emits a "rebirth" event, "command" event, and five MQTT connection events: "connect", "reconnect", "offline", "error", and "close".

Birth Event

A "birth" event is used to signal the device application that a DBIRTH message is requested. This event will be be emitted immediately after the client initially connects or re-connects with the MQTT Server.

Here is a code example of handling a "birth" event:

sparkplugClient.on('birth', function () {
    // Publish Node BIRTH certificate
    sparkplugClient.publishNodeBirth(getNodeBirthPayload());
    // Publish Device BIRTH certificate
    sparkplugClient.publishDeviceBirth(deviceId, getDeviceBirthPayload());
});

Command Events

A Device Command event is used to communicate a Device Command message (DCMD) from another MQTT client to a device. A 'dcmd' event will include the device ID and a payload containing a list of metrics (as described above). Any metrics included in the payload represent attempts to write a new value to the data points or process variables that they represent. After the device application processes the request the device application should publish a DDATA message containing any metrics that have changed or been updated.

Here is a code example of handling a "dcmd" event:

client.on('dcmd', function (deviceId, payload) {
    console.log("received 'dcmd' event");
    console.log("device: " + device);
    console.log("payload: " + payload);

    //
    // Process metrics and create new payload containing changed metrics
    //

    client.publishDeviceData(deviceId, newPayload);
});

A Node Command event is used to communicate an Edge Node Command message (DCMD) or Edge Node Command message (NCMD) from another MQTT client to a device. An 'ncmd' event will include a payload containing a list of metrics (as described above). Any metrics included in the payload may represent attempts to write a new value to the data points or process variables that they represent or they may represent control messages sent to the edge node such as a "rebirth" request.

Here is a code example of handling a "ncmd" event:

client.on('ncmd', function (payload) {
    console.log("received 'ncmd' event");
    console.log("payload: " + payload);

    //
    // Process metrics and create new payload containing changed metrics
    //

    client.publishNodeData(newPayload);
});

Connect Event

A "connect" event is emitted when the client has connected to the server.

Here is a code example of handling a "connect" event:

client.on('connect', function () {
    console.log("received 'connect' event");
});

Reconnect Event

A "reconnect" event is emitted when the client is attempting to reconnect to the server.

Here is a code example of handling a "reconnect" event:

client.on('reconnect', function () {
    console.log("received 'reconnect' event");
});

Offline Event

An "offline" event is emitted when the client loses connection with the server.

Here is a code example of handling an "offline" event:

client.on('offline', function () {
    console.log("received 'offline' event");
});

Error Event

An "error" event is emitted when the client has experienced an error while trying to connect to the server.

Here is a code example of handling a "error" event:

client.on('error', function (error) {
    console.log("received 'error' event: " + error);
});

Close Event

A "close" event is emitted when the client's connection to the server has been closed.

Here is a code example of handling a "close" event:

client.on('close', function () {
    console.log("received 'close' event");
});

Release History

• 1.0.0 Initial release
• 1.0.2 Bug Fixes
• 1.1.0 Added more emitted events (connect, reconnect, error, close)
• 1.2.0 Added 'publishDeath' config option, updated MQTT.js version
• 2.0.0 Added support for Sparkplug B and made the version configurable.
• 3.0.0 Added events for Node Birth/Command events. Renamed 'command' event to distiguish between 'dcmd' (device commands) and 'ncmd' (node commands). Renamed 'rebirth' event to 'birth'. Updated dependency versions and removed bytebuffer as a dependency.
• 3.1.0 Added support for payload compression/decompression with DEFLATE and Gzip algorithms, added logging with Winston to replace console logging, and other minor bug fixes. Moved sparkplug payload libraries to their own project and updated dependecies.
• 3.2.0 Added new 'offline' emitted event, added configurable keep alive, updated log messages and set default level to 'info', and disabled ping rescheduling within the client.
• 3.2.1 Updated License and repo links, cleaned up logging.
• 3.2.2 Bug Fixes

License

Copyright (c) 2016-2018 Cirrus Link Solutions

All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse Public License v1.0 which accompanies this distribution, and is available at http://www.eclipse.org/legal/epl-v10.html

Contributors: Cirrus Link Solutions