Class MessageTransport

java.lang.Object

com.codename1.backend.messaging.MessageTransport

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

PollingTransport

public abstract class MessageTransport
extends Object
implements Closeable

A broker connection: what sends messages and runs subscriptions. One per server, opened by Messaging.current() from the configuration; application code sends through MessageTemplate and receives through @MessageListener methods rather than calling this directly.

Delivery is at least once. A handler that returns acknowledges its message; one that throws has it delivered again after a backoff, and after cn1.messaging.retry.max-attempts deliveries it goes to the destination's dead-letter destination, <destination>.dlq, with the failure in its Message.ERROR header.

Constructor Summary

Constructors

Constructor	Description
MessageTransport()

Method Summary

Modifier and Type	Method	Description
abstract void	close()	Stops every subscription and closes the connection.
abstract String	getName()	The scheme this transport was opened for: memory, db, redis, amqp, kafka.
boolean	isHealthy()	Whether the broker answers, for the health endpoint.
boolean	isTransactional()	Whether a send is part of the calling thread's database transaction by itself, so it needs no outbox.
abstract void	send(Message message)	Sends message.
abstract Subscription	subscribe(String destination, String group, int concurrency, MessageHandler handler)	Starts concurrency consumers of destination in group.

Methods inherited from class Object

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

Constructor Details

MessageTransport

public MessageTransport()

Method Details

getName

public abstract String getName()

The scheme this transport was opened for: memory, db, redis, amqp, kafka.

send

public abstract void send(Message message)
                   throws IOException

Sends message. With a database transport inside a transaction the message is written in that transaction and is seen only if it commits.

Throws:

IOException

subscribe

public abstract Subscription subscribe(String destination,
 String group,
 int concurrency,
 MessageHandler handler)
                                throws IOException

Starts concurrency consumers of destination in group.

• group: subscriptions of one group share the messages between them, and each group sees every message -- on a transport with groups (Redis Streams, Kafka, AMQP through one queue per group). On memory: and db: a destination is a queue and every subscription competes for it.

Throws:

IOException

isTransactional

public boolean isTransactional()

Whether a send is part of the calling thread's database transaction by itself, so it needs no outbox.

isHealthy

public boolean isHealthy()

Whether the broker answers, for the health endpoint. Never throws.

close

public abstract void close()

Stops every subscription and closes the connection. Never throws.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable