io.openmessaging.consumer

Interface PullConsumer

All Superinterfaces:

ServiceLifecycle

public interface PullConsumer
extends ServiceLifecycle

A PullConsumer pulls messages from the specified queue, and supports submit the consume result by acknowledgement.

Since:

OMS 1.0.0

Version:

OMS 1.0.0

See Also:

MessagingAccessPoint.createPullConsumer()

Method Summary

Modifier and Type	Method and Description
void	ack(String receiptHandle) Acknowledges the specified and consumed message with the unique message receipt handle.
void	ack(String receiptHandle, KeyValue attributes) Acknowledges the specified and consumed message with the specified attributes.
PullConsumer	attachQueue(String queueName) Attaches the PullConsumer to a specified queue.
PullConsumer	attachQueue(String queueName, KeyValue attributes) Attaches the PullConsumer to a specified queue with some specified attributes..
KeyValue	attributes() Returns the attributes of this PullConsumer instance.
PullConsumer	detachQueue(String queueName) Detaches the PullConsumer from a specified queue.
Message	receive() Receives the next message from the attached queues of this consumer.
Message	receive(KeyValue attributes) Receives the next message from the attached queues of this consumer, using the specified attributes.

Methods inherited from interface io.openmessaging.ServiceLifecycle

shutdown, startup

Method Detail

attributes

KeyValue attributes()

Returns the attributes of this PullConsumer instance. Changes to the return KeyValue are not reflected in physical PullConsumer.

There are some standard attributes defined by OMS for PullConsumer:

• OMSBuiltinKeys.CONSUMER_ID, the unique consumer id for a consumer instance.
• OMSBuiltinKeys.OPERATION_TIMEOUT, the default timeout period for operations of PullConsumer.

Returns:

the attributes

attachQueue

PullConsumer attachQueue(String queueName)

Attaches the PullConsumer to a specified queue.

Parameters:

queueName - a specified queue

Returns:

this PullConsumer instance

attachQueue

PullConsumer attachQueue(String queueName,
                         KeyValue attributes)

Attaches the PullConsumer to a specified queue with some specified attributes..

Parameters:

queueName - a specified queue

attributes - some specified attributes

Returns:

this PullConsumer instance

detachQueue

PullConsumer detachQueue(String queueName)

Detaches the PullConsumer from a specified queue.

After the success call, this consumer won't receive new message from the specified queue any more.

Parameters:

queueName - a specified queue

Returns:

this PullConsumer instance

receive

Message receive()

Receives the next message from the attached queues of this consumer.

This call blocks indefinitely until a message is arrives, the timeout expires, or until this PullConsumer is shut down.

Returns:

the next message received from the attached queues, or null if the consumer is concurrently shut down or the timeout expires

Throws:

OMSRuntimeException - if the consumer fails to pull the next message due to some internal error.

receive

Message receive(KeyValue attributes)

Receives the next message from the attached queues of this consumer, using the specified attributes.

This call blocks indefinitely until a message is arrives, the timeout expires, or until this PullConsumer is shut down.

Parameters:

attributes - the specified attributes

Returns:

the next message received from the attached queues, or null if the consumer is concurrently shut down or the timeout expires

Throws:

OMSRuntimeException - if the consumer fails to pull the next message due to some internal error.

ack

void ack(String receiptHandle)

Acknowledges the specified and consumed message with the unique message receipt handle.

Messages that have been received but not acknowledged may be redelivered.

Parameters:

receiptHandle - the receipt handle associated with the consumed message

Throws:

OMSRuntimeException - if the consumer fails to acknowledge the messages due to some internal error.

ack

void ack(String receiptHandle,
         KeyValue attributes)

Acknowledges the specified and consumed message with the specified attributes.

Messages that have been received but not acknowledged may be redelivered.

Parameters:

receiptHandle - the receipt handle associated with the consumed message

attributes - the specified attributes

Throws:

OMSRuntimeException - if the consumer fails to acknowledge the messages due to some internal error.