org.apache.pulsar.client.api.interceptor

Interface ProducerInterceptor

All Superinterfaces:

AutoCloseable

All Known Implementing Classes:

ProducerInterceptorWrapper

@InterfaceAudience.Public
 @InterfaceStability.Stable
public interface ProducerInterceptor
extends AutoCloseable

A plugin interface that allows you to intercept (and possibly mutate) the messages received by the producer before they are published to the Pulsar brokers.

Exceptions thrown by ProducerInterceptor methods will be caught, logged, but not propagated further.

ProducerInterceptor callbacks may be called from multiple threads. Interceptor implementation must ensure thread-safety, if needed.

Since the producer may run multiple interceptors, a particular interceptor will be called in the order specified by ProducerBuilder.intercept(ProducerInterceptor...).

Method Summary

Modifier and Type	Method and Description
Message	beforeSend(Producer producer, Message message) This is called from Producer.send(Object) and Producer.sendAsync(Object) methods, before send the message to the brokers.
void	close() Close the interceptor.
boolean	eligible(Message message) Check whether the interceptor is eligible for this message.
void	onSendAcknowledgement(Producer producer, Message message, MessageId msgId, Throwable exception) This method is called when the message sent to the broker has been acknowledged, or when sending the message fails.

Method Detail

close

void close()

Close the interceptor.

Specified by:

close in interface AutoCloseable

eligible

boolean eligible(Message message)

Check whether the interceptor is eligible for this message.

Parameters:

message - message to send

Returns:

whether the interceptor can be applied to this particular message.

beforeSend

Message beforeSend(Producer producer,
                   Message message)

This is called from Producer.send(Object) and Producer.sendAsync(Object) methods, before send the message to the brokers. This method is allowed to modify the record, in which case, the new record will be returned.

Any exception thrown by this method will be caught by the caller and logged, but not propagated further.

Each interceptor will be passed the message returned by the last successful executed interceptor or the original message if it is the first one. Since interceptors are allowed to modify messages, interceptors may potentially get the message already modified by other interceptors. However, building a pipeline of mutable interceptors that depend on the output of the previous interceptor is discouraged, because of potential side-effects caused by interceptors potentially failing to modify the message and throwing an exception.

Parameters:

producer - the producer which contains the interceptor.

message - message to send

Returns:

the intercepted message

onSendAcknowledgement

void onSendAcknowledgement(Producer producer,
                           Message message,
                           MessageId msgId,
                           Throwable exception)

This method is called when the message sent to the broker has been acknowledged, or when sending the message fails. This method is generally called just before the user callback is called, and in additional cases when an exception on the producer side.

Any exception thrown by this method will be ignored by the caller.

This method will generally execute in the background I/O thread, so the implementation should be reasonably fast. Otherwise, sending of messages from other threads could be delayed.

Parameters:

producer - the producer which contains the interceptor.

message - the message that application sends

msgId - the message id that assigned by the broker; null if send failed.

exception - the exception on sending messages, null indicates send has succeed.