AWS IoT Core v2

This library is a built-in class that provides functions to communicate with AWS IoT Core.

Library usage requirements
Type	Integrations
Name	AWS_IoT_Core_V2
Version	2020-11-04
Code size used	2.3KB
Resources used	HTTPS x 1, MQTT x 1, Timers x 1

Abstracts

Methods()/Properties	Summary
`new AWS_IOT_CORE()`	Initializes the `AWS_IOT_CORE` object with the passed configuration.

{AWS_IOT_CORE} Instance

Methods()/Properties	Summary
`.httpPost()`	Send data over HTTPS to an AWS IoT Core endpoint.
`.abortHttpRequest()`	Abort the currently ongoing HTTP request.
`.mqttConnect()`	Connect to AWS IoT Core over MQTT.
`.errors`	An array containing the invalid configuration key names. Exists only when an invalid configuration is passed to `setConfig` or the constructor.

Details

`new AWS_IOT_CORE(config)`

Initializes the AWS_IOT_CORE instance with the passed configuration.

Configuration

When instantiating the AWS_IOT_CORE instance, the following configuration options are mandatory:

Name	Type	Default	Summary
`host`	string	MANDATORY	The AWS IoT endpoint for requests, found on the AWS IoT Core console settings page.
`deviceCert`	string	MANDATORY	The X.509 certificate associated with this device.
`devicePrivKey`	string	MANDATORY	The private key associated with this device.
`ca`	string	MANDATORY	The root CA necessary to connect to AWS IoT Core.
`timeout`	Number	90000	HTTP request timeout, in ms.

config must be a JavaScript object in the following form:

var config = {
    host: "<String>",
    deviceCert: "<String>",
    devicePrivKey: "<String>",
    ca: "<String>",
    timeout: "<Number>"
};

Once the configuration object has been created, it can be passed to AWS_IOT_CORE during instance creation. If any invalid values are passed, the invalid key names are stored in the errors property, and should be handled appropriately.

var iot = new AWS_IOT_CORE(config);
if ('errors' in iot) {
    // TODO: handle errors
}

Setter Methods

After creating an instance of the AWS_IOT_CORE object, each of the aforementioned configurations may be changed by its corresponding setter function. If an invalid value is passed to any setter, it returns false.

Setter	Summary
`.setHost(value: String)`	Set the AWS IoT Core endpoint for requests.
`.setDeviceCert(deviceCert: String)`	Set the certificate for your Thing. The certificate can be generated when the Thing is created in the AWS IoT Core console. Refer to the AWS IoT Core Documentation for more information on creating and activating the device certificate. Why is this information necessary?
`.setDevicePrivKey(devicePrivKey: String)`	Set the private key for your Thing for use in authentication. The private key can be generated when the Thing is created in the AWS IoT Core console. Refer to the AWS IoT Core Documentation for more information on creating the private key. Why is this information necessary?
`.setTimeout(value: Number)`	Set the HTTP request timeout.
`.setRootCA(value: String)`	Set the root CA used for making requests.

`.setConfig(config)`

The setConfig function can be used to set or change multiple configuration options at the same time. This function expects a typical JavaScript object of key:value pairs as an argument. If any invalid values are passed, this returns an array containing the names of each invalid key, and sets the errors property to that array. When a valid config is passed to setConfig, if errors exists, it is removed.

iot.setConfig({
    host: "value",
    deviceCert: "value",
    devicePrivKey: "value",
    ca: "value",
    timeout: 90000
});

Instance Methods

`.httpPost(topic,headers,getNextChunk,callback[,qos])`

Post data over HTTPS to the AWS IoT Core endpoint specified by topic. Ensure that the proper AWS IoT Core Policies are set for the Thing before use.

Name	Type	Default	Summary
`topic`	string	MANDATORY	The MQTT Topic.
`headers`	object	MANDATORY	The desired HTTP headers for this request. "Content-Length" is required for successful execution.
`getNextChunk`	function	MANDATORY	Callback for retrieving the data to send. Returns data in [string/ArrayBuffer] chunks of 4KB or less until exhausted, then returns `null`.
`callback(err, resp)`	function	MANDATORY	The user's callback function, to handle the response. Will pass an Error as `err` and a Response as `resp`.
`qos`	Number	0	The desired QoS value for this request. AWS Documentation on QoS
return	undefined	-	-

Responses

This library uses an object to handle AWS IoT Core responses. These responses are always in the following format:

{
    statusCode: <Number>,
    statusMessage: <String>,
    body: <String>
}

More details on statusCode and statusMessage can be seen in the HTTPS documentation for the appropriate device (NEQTO Bridge | Spresense).

body is the HTTP response data.

Errors

This library passes an Error object from HTTP errors into the user-provided callback. Error objects have the following form:

{
    errCode: <Number>
}

This errCode parameter has more information in the appropriate neqto.js documentation (NEQTO Bridge | Spresense).

`.abortHttpRequest()`

Abort the currently ongoing HTTP request.

Name	Type	Default	Summary
return	undefined	-	-

`.mqttConnect([options])`

Establish a connection with the AWS IoT Core MQTT endpoint. Ensure that the proper AWS IoT Core Policies are set for the Thing before use.

Name	Type	Default	Summary
`options`	object	{}	The `options` object from the neqto.js `mqtt.connect` method.
return	MQTT.Client	-	An MQTT Client connected to AWS IoT Core. See the device's appropriate MQTT page for more details on this object. - NEQTO Bridge - Spresense - AWS Documentation on QoS

Usage Examples

Click here to learn how to get the CA that can be used in the config option.

Verify that the root CA is appropriate for the target IoT Core endpoint.

var rootCa = '-----BEGIN CERTIFICATE-----\n...<CA>...\n-----END CERTIFICATE-----';

The following sample code sections all use the following configuration:

// IMPORTED LIBRARIES
// - AWS_IoT_Core_V2

// Logging setup
log.setLevel(0,2); //-1:NONE 0:ERROR 1:WARNING 2:DEBUG 3:TRACE, 0:DISABLE 1:LOG 2:CONSOLE 3:BOTH
log.printLevel(2); //0:DISABLE 1:LOG 2:CONSOLE 3:BOTH

// Device setup
var deviceCert = "[certificate]";
var deviceKey = "[key]";
var host = "host.iot.ap-northeast-170.amazon.aws.com"
var config = {
    host: host,
    deviceCert: deviceCert,
    devicePrivKey: deviceKey,
    ca: rootCa
}
var iotCore = new AWS_IOT_CORE(config);

if ('errors' in iotCore) {
    // TODO: handle errors
    throw 'Invalid configuration'
}

Sample 1: MQTT With Automatic Reconnection

var client = iotCore.mqttConnect( {reconnectCount: 1855} );
if (!client) {
    throw 'Failed to create mqtt instance';
}
client.on('error', function(err) {
    print('ERROR: ' + err.code + ' ERRNO: ' + client.get('errnoConnect'));
    //TODO: Error handling
});
client.on('message', function(topic, message) {
    print('TOPIC: ' + topic + ' MESSAGE: ' + message);
    //TODO: Message handling
});
client.on('connect', function() {
    print("CONNECTED");
    client.subscribe("testtopic/subtopic/#", { qos: 1 }, function(err) {
        if (err.code > 0) {
            print("MQTT SUBSCRIBE ERROR", err.code);
            //TODO: Error handling
        }
    });
    client.subscribe("shadowtopic/#", { qos: 1 }, function(err) {
        if (err.code > 0) {
            print("MQTT SUBSCRIBE ERROR", err.code);
            //TODO: Error handling
        }
    });
});
setInterval(function() {
    if (client.canPublish()) {
        var body = JSON.stringify({ "message" : "dummy" })
        client.publish("testtopic/subtopic/dummy", body, { qos: 1 }, function(err){
            if(err.code == 0){
                print('Publish OK');
            } else {
                print('Publish failed');
                //TODO: Error handling
            }
        });
    } else {
        print('Cannot publish');
    }
}, 15000);

Sample 2: MQTT With Manual Reconnect

var reconnectAttempts = 0;
var maxReconnectAttempts = 24;
var registerEventHandlers = function(mqClient) {
    if (!mqClient) {
        return;
    }
    mqClient.on('error', function(err) {
        print('ERROR: ' + err.code + ' ERRNO: ' + mqClient.get('errnoConnect'));
        if (err.code == 1) { //Connection failed
            if (reconnectAttempts++ < maxReconnectAttempts) {
                print('reconnectAttempts:', reconnectAttempts);
                mqClient.reconnect();
            } else {
                print('ABORT');
                reconnectAttempts = 0;
                mqClient.end(); //Release mqtt instance
                client = undefined;
            }
        }
    });
    mqClient.on('message', function(topic, message) {
        print('TOPIC: ' + topic + ' MESSAGE: ' + message);
        //TODO: Message handling
    });
    mqClient.on('close', function() {
        print("DISCONNECTED");
        mqClient.reconnect();
    });
    mqClient.on('connect', function() {
        reconnectAttempts = 0;
        print("CONNECTED");
        mqClient.subscribe("testtopic/subtopic/#", { qos: 1 }, function(err) {
            if (err.code > 0) {
                print("MQTT SUBSCRIBE ERROR", err.code);
                //TODO: Error handling
            }
        });
    });
}
client = iotCore.mqttConnect();
if (!client) {
    throw 'Failed to create mqtt instance';
}
registerEventHandlers(client);
setInterval(function() {
    if (!client) {
        print('mqtt instance recreate');
        client = iotCore.mqttConnect();
        registerEventHandlers(client);
    }
    if (client && client.canPublish()) {
        var body = JSON.stringify({ "message" : "dummy" });
        client.publish("testtopic/subtopic/dummy", body, { qos: 1 }, function(err){
            if(err.code == 0){
                print('Publish OK');
            } else {
                print('Publish failed');
                //TODO: Error handling
            }
        });
    }
}, 15000);

Sample 3: Basic HTTP Usage

var body = JSON.stringify({
    "message": "HTTP post"
});
var headers = {
    "Content-Length": body.length.toString()
}
// A simple method that returns `body` once, then `null` all other times.
var getBody = function() {
    var temp = body;
    body = null;
    return temp;
}

// A very simple callback to handle the HTTP response
var callback = function(err, res) {
    if (err) print(JSON.stringify(err));
    if (res) print(JSON.stringify(res));
}

iotCore.httpPost("testtopic/shadowtopic/dummy", headers, getBody, callback);

Sample 4: HTTP with Chunks

var body = JSON.stringify({
    "message": "This is a really long string[...]"
});
var headers = {
    "Content-Length": body.length.toString()
}
// This is a *dummy* example of how to chunk data for return.
// If the data is actually larger than 4KB, it is best to chunk it in the way that makes most sense.
var index = 0;
var getBody = function() {
    var ival = 8;
    var ret = body.substring(index, index + ival);
    if (ret) {
        index = index + ival;
        return ret;
    }
    return null;
}

// A very simple callback to handle the HTTP response
var callback = function(err, res) {
    if (err) print(JSON.stringify(err));
    if (res) print(JSON.stringify(res));
}

iotCore.httpPost("testtopic/shadowtopic/dummy", headers, getBody, callback);

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Updated: 2023-01-20

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Related Documents

Abstracts

{AWS_IOT_CORE} Instance

Details

`new AWS_IOT_CORE(config)`

Configuration

Setter Methods

`.setConfig(config)`

Instance Methods

`.httpPost(topic,headers,getNextChunk,callback[,qos])`

Responses

Errors

`.abortHttpRequest()`

`.mqttConnect([options])`

Usage Examples

Sample 1: MQTT With Automatic Reconnection

Sample 2: MQTT With Manual Reconnect

Sample 3: Basic HTTP Usage

Sample 4: HTTP with Chunks