Chapter 7. MQ Telemetry Transport(MQTT) Protocol
Abstract
MQTT is a machine-to-machine (M2M)/"Internet of Things" connectivity protocol. It was designed as a lightweight publish/subscribe messaging transport.
URI syntax
Example 7.1, “MQTT URI” shows the syntax for an MQTT connection.
Example 7.1. MQTT URI
mqtt://Host:[Port]?transportOptions
An NIO URI has the syntax shown in Example 7.2, “Syntax for MQTT+NIO Connection”.
Example 7.2. Syntax for MQTT+NIO Connection
mqtt+nio://Host[:Port]?transportOptions
A secure MQTT URI has the syntax shown in Example 7.3, “Syntax for an MQTT SSL Connection”.
Example 7.3. Syntax for an MQTT SSL Connection
mqtt+ssl://Host[:Port]?transportOptions
A secure MQTT+NIO URI has the syntax shown in Example 7.4, “Syntax for a MQTT+NIO SSL Connection”.
Example 7.4. Syntax for a MQTT+NIO SSL Connection
mqtt+nio+ssl://Host[:Port]?transportOptions
Transport options
The MQTT protocol supports the following transport options:
| Property | Default | Description |
|---|---|---|
transport.defaultKeepAlive | 0 |
Specifies, in milliseconds, the broker will allow a connection to be silent before it is closed. If a client specifies a keep-alive duration, this setting is ignored. This option is set in the
uri attribute of a broker's transportConnector element.
|
jms.* | All the properties with this prefix are used to configure client connections to a broker. See Appendix B, Client Connection Options for more information. |
SSL transport options
In addition to the options supported by the non-secure MQTT transports, the SSL transport also supports the options for configuring the
SSLServerSocket created for the connection. These options are listed in Table 2.1, “SSL Transport Options”.
Warning
If you are planning to enable SSL/TLS security, you must ensure that you explicitly disable the SSLv3 protocol, in order to safeguard against the Poodle vulnerability (CVE-2014-3566). For more details, see Disabling SSLv3 in JBoss Fuse 6.x and JBoss A-MQ 6.x.
Configuring broker SSL options
On the broker side, you must specify an SSL transport option using the syntax
transport.OptionName. For example, to enable an MQTT SSL port on a broker, you would add the following transport element:
<transportConnector name="mqttssl" uri="mqtt+ssl://localhost:61617?transport.enabledProtocols=TLSv1,TLSv1.1,TLSv1.2" />
Tip
Remember, if you are specifying more than one option in the context of XML, you need to escape the ampersand,
&, between options as &.
Configuring client SSL options
On the client side, you must specify an SSL transport option using the syntax
socket.OptionName. For example, to connect to a MQTT SSL port, you would use a URL like the following:
mqtt+ssl://localhost:61617?socket.enabledProtocols=TLSv1,TLSv1.1,TLSv1.2
