Mosquitto-PHP

This is an extension to allow using the Mosquitto MQTT library with PHP. See the examples/ directory for usage.

Requirements

• PHP 5.3+
• libmosquitto 1.2.x or later
• Linux or Mac OS X. I do not have a Windows machine handy, though patches or pull requests are of course very welcome!

Installation

If you've used a pre-built package to install Mosquitto, you need to make sure you have the development headers installed. On Red Hat-derived systems, this is probably called libmosquitto-devel, and on Debian-based systems it will be libmosquitto-dev.

You may obtain this package using PECL:

pecl install Mosquitto-alpha

Alternatively, you can use the normal extension build process:

phpize
./configure --with-mosquitto=/path/to/libmosquitto
make
make install

Then add extension=mosquitto.so to your php.ini.

The --with-mosquitto argument is optional, and only required if your libmosquitto install cannot be found.

General operation

The underlying library is based on callbacks and asynchronous operation. As such, you have to call the loop() method of the Client frequently to permit the library to handle the messages in its queues. Also, you should use the callback functions to ensure that you only attempt to publish after the client has connected, etc. For example, here is how you would correctly publish a QoS=2 message:

<?php

$c = new Mosquitto\Client;
$c->onConnect(function() use ($c) {
    $c->publish('mgdm/test', 'Hello', 2);
});

$c->connect('test.mosquitto.org');

for ($i = 0; $i < 100; $i++) {
    // Loop around to permit the library to do its work
    $c->loop(1);
}

echo "Finished\n";

API Documentation

The classes in this extension are namespaced.

Class Mosquitto\Client

This is the actual Mosquitto client.

1. __construct - create a new client
2. setCredentials - set the credentials to use on connection
3. setTlsCertificates - set the TLS certificate sources
4. setTlsInsecure - Set verification of the server hostname in TLS certificates
5. setTlsOptions - Set advanced TLS options
6. setTlsPSK - Configure the client for pre-shared-key based TLS support.
7. setWill - set the client will, to be delivered if disconnected uncleanly
8. clearWill - clear a previously-set will
9. setReconnectDelay - set the behaviour if disconnected uncleanly
10. connect - connect to an MQTT broker
11. disconnect - disconnect from an MQTT broker
12. onConnect - set the connect callback
13. onDisconnect - set the disconnect callback
14. onLog - set the logging callback
15. onSubscribe - set the subscribe callback
16. onMessage - set the callback fired when a message is received
17. onPublish - set the callback fired when a message is published
18. setMaxInFlightMessages - set the number of QoS 1 and 2 messages that can be "in flight" at once
19. setMessageRetry - set the number of seconds to wait before retrying messages
20. publish - publish a message to a broker
21. subscribe - subscribe to a topic
22. unsubscribe - unsubscribe from a topic
23. loop - The main network loop
24. loopForever - run loop() in an infinite blocking loop

__construct

Creates a new Client instance.

Parameter	Type	Description
id	string	Client ID. Optional. If not supplied or NULL, one will be generated at random.
clean_session	boolean	Set to true to instruct the broker to clean all messages and subscriptions on disconnect.

setCredentials

Set the username and password to use on connecting to the broker. Must be called before connect().

Parameter	Type	Description
Username	string	Username to supply to the broker
Password	string	Password to supply to the broker

setTlsCertificates

Configure the client for certificate based SSL/TLS support. Must be called before connect(). Cannot be used in conjunction with setTlsPSK().

Define the Certificate Authority certificates to be trusted (ie. the server certificate must be signed with one of these certificates) using cafile. If the server you are connecting to requires clients to provide a certificate, define certfile and keyfile with your client certificate and private key. If your private key is encrypted, provide the password as the fourth parameter, or you will have to enter the password at the command line.

Parameter	Type	Description
capath	string	Path to the PEM encoded trusted CA certificate files, or to a directory containing them
certfile	string	Path to the PEM encoded certificate file for this client. Optional.
keyfile	string	Path to a file containing the PEM encoded private key for this client. Required if certfile is set.
password	string	The password for the keyfile, if it is encrypted. If null, the password will be asked for on the command line.

setTlsInsecure

Configure verification of the server hostname in the server certificate. If value is set to true, it is impossible to guarantee that the host you are connecting to is not impersonating your server. Do not use this function in a real system. Must be called before connect().

Parameter	Type	Description
value	boolean	If set to false, the default, certificate hostname checking is performed. If set to true, no hostname checking is performed and the connection is insecure.

setTlsOptions

Set advanced SSL/TLS options. Must be called before connect().

Parameter	Type	Description
certReqs	int	Whether or not to verify the server. Can be Mosquitto\Client::SSL_VERIFY_NONE, to disable certificate verification, or Mosquitto\Client::SSL_VERIFY_PEER (the default), to verify the server certificate.
tlsVersion	string	The TLS version to use. If NULL, a default is used. The default value depends on the version of OpenSSL the library was compiled against. Available options on OpenSSL >= 1.0.1 are 'tlsv1.2', 'tlsv1.1' and 'tlsv1'.
cipers	string	A string describing the ciphers available for use. See the openssl ciphers tool for more information. If NULL, the default set will be used.

setTlsPSK

Configure the client for pre-shared-key based TLS support. Must be called before connect(). Cannot be used in conjunction with setTlsCertificates.

Parameter	Type	Description
psk	string	The pre-shared key in hex format with no leading "0x".
identity	string	The identity of this client. May be used as the username depending on server settings.
cipers	string	Optional. A string describing the ciphers available for use. See the openssl ciphers tool for more information. If NULL, the default set will be used.

setWill

Set the client "last will and testament", which will be sent on an unclean disconnection from the broker. Must be called before connect().

Parameter	Type	Description
topic	string	The topic on which to publish the will.
payload	string	The data to send.
qos	int	Optional. Default 0. Integer 0, 1, or 2 indicating the Quality of Service to be used.
retain	boolean	Optional. Default false. If true, the message will be retained.

clearWill

Remove a previously-set will. No parameters.

setReconnectDelay

Control the behaviour of the client when it has unexpectedly disconnected in loopForever. The default behaviour if this method is not used is to repeatedly attempt to reconnect with a delay of 1 second until the connection succeeds.

Parameter	Type	Description
reconnect_delay	int	Set delay between successive reconnection attempts.
reconnect_delay	int	Set max delay between successive reconnection attempts when exponential backoff is enabled
exponential_backoff	bool	Enable exponential backoff

connect

Connect to an MQTT broker.

Parameter	Type	Description
host	string	Hostname to connect to
port	int	Optional. Port number to connect to. Defaults to 1883.
keepalive	int	Optional. Number of sections after which the broker should PING the client if no messages have been recieved.
interface	string	Optional. The address or hostname of a local interface to bind to for this connection.

disconnect

Disconnect from the broker. No parameters.

onConnect

Set the connect callback. This is called when the broker sends a CONNACK message in response to a connection.

Parameter	Type	Description
callback	callback	The callback

The callback should take parameters of the form:

Parameter	Type	Description
rc	int	Response code from the broker.
message	string	String description of the response code.

Response codes are as follows:

Code	Meaning
0	Success
1	Connection refused (unacceptable protocol version)
2	Connection refused (identifier rejected)
3	Connection refused (broker unavailable )
4-255	Reserved for future use

onDisconnect

Set the disconnect callback. This is called when the broker has received the DISCONNECT command and has disconnected the client.

Parameter	Type	Description
callback	callback	The callback

The callback should take parameters of the form:

Parameter	Type	Description
rc	int	Reason for the disconnection. 0 means the client requested it. Any other value indicates an unexpected disconnection.

onLog

Set the logging callback.

Parameter	Type	Description
callback	callback	The callback

The callback should take parameters of the form:

Parameter	Type	Description
level	int	The log message level from the values below
str	string	The message string.

The level can be one of:

• Mosquitto\Client::LOG_DEBUG
• Mosquitto\Client::LOG_INFO
• Mosquitto\Client::LOG_NOTICE
• Mosquitto\Client::LOG_WARNING
• Mosquitto\Client::LOG_ERR

onSubscribe

Set the subscribe callback. This is called when the broker responds to a subscription request.

Parameter	Type	Description
callback	callback	The callback

The callback should take parameters of the form:

Parameter	Type	Description
mid	int	Message ID of the subscribe message
qos_count	int	Number of granted subscriptions

This function needs to return the granted QoS for each subscription, but currently cannot.

onUnsubscribe

Set the unsubscribe callback. This is called when the broker responds to a unsubscribe request.

Parameter	Type	Description
callback	callback	The callback

The callback should take parameters of the form:

Parameter	Type	Description
mid	int	Message ID of the unsubscribe message

onMessage

Set the message callback. This is called when a message is received from the broker.

Parameter	Type	Description
callback	callback	The callback

The callback should take parameters of the form:

Parameter	Type	Description
message	Mosquitto\Message	A Message object containing the message data

onPublish

Set the publish callback, This is called when a message is publish by the client itself.

Warning: this may be called before the method Mosquitto\Client::publish return the message id, so, you need to create a queue to deal with the mid list

Parameter	Type	Description
callback	callback	The callback

The callback should take parameters of the form:

Parameter	Type	Description
mid	int	the message id returned by Mosquitto\Client::publish

setMaxInFlightMessages

Set the number of QoS 1 and 2 messages that can be “in flight” at one time. An in flight message is part way through its delivery flow. Attempts to send further messages with publish() will result in the messages being queued until the number of in flight messages reduces.

Set to 0 for no maximum.

Parameter	Type	Description
max_inflight_messages	int	The maximum

setMessageRetry

Set the number of seconds to wait before retrying messages. This applies to publish messages with QoS>0. May be called at any time.

Parameter	Type	Description
message_retry	int	The retry period

publish

Publish a message on a given topic.

Parameter	Type	Description
topic	string	The topic to publish on
payload	string	The message payload
qos	int	Integer value 0, 1 or 2 indicating the QoS for this message
retain	boolean	If true, make this message retained

return int the message id in broker system Warning the message id is not unique

subscribe

Subscribe to a topic.

Parameter	Type	Description
topic	string	The topic.
qos	The QoS to request for this subscription

Returns the message ID of the subscription message, so this can be matched up in the onSubscribe callback.

unsubscribe

Unsubscribe from a topic.

Parameter	Type	Description
topic	string	The topic.
qos	The QoS to request for this subscription

Returns the message ID of the subscription message, so this can be matched up in the onUnsubscribe callback.

loop

The main network loop for the client. You must call this frequently in order to keep communications between the client and broker working. If incoming data is present it will then be processed. Outgoing commands, from e.g. publish(), are normally sent immediately that their function is called, but this is not always possible. loop() will also attempt to send any remaining outgoing messages, which also includes commands that are part of the flow for messages with QoS>0.

Parameter	Type	Description
timeout	int	Optional. Number of milliseconds to wait for network activity. Pass 0 for instant timeout. Defaults to 1000.
max_packets	int	Currently unused.

loopForever

Call loop() in an infinite blocking loop. Callbacks will be called as required. This will handle reconnecting if the connection is lost. Call disconnect() in a callback to return from the loop.

Note: exceptions thrown in callbacks do not currently cause the loop to exit. To work around this, use loop() and wrap your own loop structure around it such as a while().

Parameter	Type	Description
timeout	int	Optional. Number of milliseconds to wait for network activity. Pass 0 for instant timeout. Defaults to 1000.
max_packets	int	Currently unused.

Class Mosquitto\Message

Represents a message received from a broker. All data is represented as properties.

Property	Type	Description
topic	string	The topic this message was delivered to.
payload	string	The payload of this message.
mid	int	The ID of this message.
qos	int	The QoS value applied to this message.
retain	bool	Whether this is a retained message or not.

This class has two static methods.

topicMatchesSub

Returns true if the supplied topic matches the supplied description, and otherwise false.

Parameter	Type	Description
topic	string	The topic to match
subscription	string	The subscription to match

tokeniseTopic

Tokenise a topic or subscription string into an array of strings representing the topic hierarchy.

Parameter	Type	Description
topic	string	The topic to tokenise

Class Mosquitto\Exception

This is an exception that may be thrown by many of the operations in the Client object.

To do

• Arginfo
• Logging callbacks
• TLS support
• Tests