org.eclipse.microprofile.reactive.messaging

Annotation Type Channel

@Qualifier
 @Retention(value=RUNTIME)
 @Target(value={METHOD,CONSTRUCTOR,FIELD,PARAMETER})
 @Experimental(value="smallrye-only, added to the specification")
public @interface Channel

This qualifier indicates which channel should be injected / populated.

This qualifier can be used to inject a Channel containing the items and signals propagated by the specified channel. For example, it can be used to @Inject a Publisher representing a channel managed by the Reactive Messaging implementation.

Can be injected:

• Publisher<X> with X the payload type
• Publisher<Message<X>> with X the payload type
• PublisherBuilder<Message<X>> with X the payload type
• PublisherBuilder<X> with X the payload type

When this qualifier is used on an Emitter, it indicates which channel received the emitted values / signals:

 
 @Inject @Channel("my-channel") Emitter<String> emitter;

 // ...
 emitter.send("a");
 
 

A subscriber for the above channel must be found by the time a message is emitted to the channel. Otherwise, IllegalStateException must be thrown.

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
String	value The name of the channel (indicated in the @Outgoing annotation.

Element Detail

value

public abstract String value

The name of the channel (indicated in the @Outgoing annotation.

Returns:

the channel name, mandatory, non-null and non-blank. It must matches one of the available channels.