Package com.framed.interop.mqtt

Class PahoMqttTransport

java.lang.Object

com.framed.interop.mqtt.PahoMqttTransport

All Implemented Interfaces:

MqttTransport

public final class PahoMqttTransport
extends Object
implements MqttTransport

MqttTransport backed by the Eclipse Paho MQTT 3.1.1 asynchronous client.

The async client is used deliberately so publish(java.lang.String, byte[], int) never blocks the calling thread on network I/O: it hands the message to Paho's sender and returns immediately. This matters because publishes originate on the FRAMED bus handler thread, which must stay responsive (the synchronous MqttClient would block until the broker acknowledges, indefinitely while it is down). connect() and subscribe(java.lang.String, int, java.util.function.BiConsumer<java.lang.String, byte[]>) run only at startup and wait with a bounded timeout.

A single Paho callback dispatches each incoming message to every distinct handler whose topic filter matches, so one connection can serve multiple inbound filters. A handler registered under several overlapping filters (e.g. a/# and a/+) is invoked at most once per delivery. Note that with overlapping filters the broker itself may still deliver one copy per matching subscription (permitted by MQTT 3.1.1 §3.3.5) — prefer non-overlapping subscribe filters.

Constructor Summary

Constructors

Constructor	Description
PahoMqttTransport(String brokerUrl, String clientId)

Method Summary

Modifier and Type	Method	Description
void	close()	Closes the connection and releases resources.
void	connect()	Establishes the broker connection.
void	publish(String topic, byte[] payload, int qos)	Publishes a message.
void	subscribe(String topicFilter, int qos, BiConsumer<String,byte[]> handler)	Subscribes to a topic filter, delivering matching messages to handler as (topic, payload).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

PahoMqttTransport

public PahoMqttTransport(String brokerUrl,
 String clientId)

Parameters:

brokerUrl - broker URI (e.g. tcp://127.0.0.1:1883)

clientId - MQTT client id

Method Details

connect

public void connect()
             throws org.eclipse.paho.client.mqttv3.MqttException

Description copied from interface: MqttTransport

Establishes the broker connection.

Specified by:

connect in interface MqttTransport

Throws:

org.eclipse.paho.client.mqttv3.MqttException

publish

public void publish(String topic,
 byte[] payload,
 int qos)
             throws org.eclipse.paho.client.mqttv3.MqttException

Description copied from interface: MqttTransport

Publishes a message.

Specified by:

publish in interface MqttTransport

Parameters:

topic - the topic to publish to

payload - the message payload

qos - the MQTT quality-of-service level (0/1/2)

Throws:

org.eclipse.paho.client.mqttv3.MqttException

subscribe

public void subscribe(String topicFilter,
 int qos,
 BiConsumer<String,byte[]> handler)
               throws org.eclipse.paho.client.mqttv3.MqttException

Description copied from interface: MqttTransport

Subscribes to a topic filter, delivering matching messages to handler as (topic, payload).

Specified by:

subscribe in interface MqttTransport

Parameters:

topicFilter - the MQTT topic filter (may contain + / # wildcards)

qos - the requested QoS

handler - receives (topic, payload) for each matching message

Throws:

org.eclipse.paho.client.mqttv3.MqttException

close

public void close()

Description copied from interface: MqttTransport

Closes the connection and releases resources.

Specified by:

close in interface MqttTransport