org.pipservices.messaging.queues

Class MemoryMessageQueue

java.lang.Object

org.pipservices.messaging.queues.MessageQueue

org.pipservices.messaging.queues.MemoryMessageQueue

All Implemented Interfaces:

org.pipservices.commons.config.IConfigurable, org.pipservices.commons.refer.IReferenceable, org.pipservices.commons.run.IClosable, org.pipservices.commons.run.IOpenable, IMessageQueue

public class MemoryMessageQueue
extends MessageQueue

Message queue that sends and receives messages within the same process by using shared memory.

This queue is typically used for testing to mock real queues.

### Configuration parameters ###

• name: name of the message queue

### References ###

• *:logger:*:*:1.0 (optional) ILogger components to pass log messages
• *:counters:*:*:1.0 (optional) ICounters components to pass collected measurements

### Example ###

 
 MessageQueue queue = new MessageQueue("myqueue");
 
 queue.send("123", new MessageEnvelop(null, "mymessage", "ABC"));
 
 queue.receive("123", 0);
 
 

See Also:

MessageQueue, MessagingCapabilities

Field Summary

Fields inherited from class org.pipservices.messaging.queues.MessageQueue

_capabilities, _connectionResolver, _counters, _credentialResolver, _kind, _lock, _logger, _name

Constructor Summary

Constructors

Constructor and Description
MemoryMessageQueue() Creates a new instance of the message queue.
MemoryMessageQueue(String name) Creates a new instance of the message queue.

Method Summary

Modifier and Type	Method and Description
void	abandon(MessageEnvelop message) Returnes message into the queue and makes it available for all subscribers to receive it again.
void	clear(String correlationId) Clears component state.
void	close(String correlationId) Closes component and frees used resources.
void	complete(MessageEnvelop message) Permanently removes a message from the queue.
void	endListen(String correlationId) Ends listening for incoming messages.
Long	getMessageCount() Gets the current number of messages in the queue to be delivered.
boolean	isOpen() Checks if the component is opened.
void	listen(String correlationId, IMessageReceiver receiver) Listens for incoming messages and blocks the current thread until queue is closed.
void	moveToDeadLetter(MessageEnvelop message) Permanently removes a message from the queue and sends it to dead letter queue.
void	open(String correlationId, org.pipservices.components.connect.ConnectionParams connection, org.pipservices.components.auth.CredentialParams credential) Opens the component with given connection and credential parameters.
MessageEnvelop	peek(String correlationId) Peeks a single incoming message from the queue without removing it.
List<MessageEnvelop>	peekBatch(String correlationId, int messageCount) Peeks multiple incoming messages from the queue without removing them.
MessageEnvelop	receive(String correlationId, long waitTimeout) Receives an incoming message and removes it from the queue.
void	renewLock(MessageEnvelop message, long lockTimeout) Renews a lock on a message that makes it invisible from other receivers in the queue.
void	send(String correlationId, MessageEnvelop message) Sends a message into the queue.
String	toString() Override toString() method, string representation of queue.

Methods inherited from class org.pipservices.messaging.queues.MessageQueue

beginListen, configure, getCapabilities, getName, open, sendAsObject, setReferences

Methods inherited from class java.lang.Object

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

Constructor Detail

MemoryMessageQueue

public MemoryMessageQueue()

Creates a new instance of the message queue.

MemoryMessageQueue

public MemoryMessageQueue(String name)

Creates a new instance of the message queue.

Parameters:

name - (optional) a queue name.

See Also:

MessagingCapabilities

Method Detail

isOpen

public boolean isOpen()

Checks if the component is opened.

Specified by:

isOpen in interface org.pipservices.commons.run.IOpenable

Specified by:

isOpen in class MessageQueue

Returns:

true if the component has been opened and false otherwise.

open

public void open(String correlationId,
                 org.pipservices.components.connect.ConnectionParams connection,
                 org.pipservices.components.auth.CredentialParams credential)

Opens the component with given connection and credential parameters.

Specified by:

open in class MessageQueue

Parameters:

correlationId - (optional) transaction id to trace execution through call chain.

connection - connection parameters

credential - credential parameters

close

public void close(String correlationId)

Closes component and frees used resources.

Specified by:

close in interface org.pipservices.commons.run.IClosable

Specified by:

close in class MessageQueue

Parameters:

correlationId - (optional) transaction id to trace execution through call chain.

clear

public void clear(String correlationId)

Clears component state.

Specified by:

clear in class MessageQueue

Parameters:

correlationId - (optional) transaction id to trace execution through call chain.

getMessageCount

public Long getMessageCount()

Gets the current number of messages in the queue to be delivered.

Specified by:

getMessageCount in interface IMessageQueue

Specified by:

getMessageCount in class MessageQueue

Returns:

number of messages.

send

public void send(String correlationId,
                 MessageEnvelop message)

Sends a message into the queue.

Specified by:

send in interface IMessageQueue

Specified by:

send in class MessageQueue

Parameters:

correlationId - (optional) transaction id to trace execution through call chain.

message - a message envelop to be sent.

peek

public MessageEnvelop peek(String correlationId)

Peeks a single incoming message from the queue without removing it. If there are no messages available in the queue it returns null.

Specified by:

peek in interface IMessageQueue

Specified by:

peek in class MessageQueue

Parameters:

correlationId - (optional) transaction id to trace execution through call chain.

Returns:

a message envelop object.

peekBatch

public List<MessageEnvelop> peekBatch(String correlationId,
                                      int messageCount)

Peeks multiple incoming messages from the queue without removing them. If there are no messages available in the queue it returns an empty list.

Specified by:

peekBatch in interface IMessageQueue

Specified by:

peekBatch in class MessageQueue

Parameters:

correlationId - (optional) transaction id to trace execution through call chain.

messageCount - a maximum number of messages to peek.

Returns:

a list with messages.

receive

public MessageEnvelop receive(String correlationId,
                              long waitTimeout)

Receives an incoming message and removes it from the queue.

Specified by:

receive in interface IMessageQueue

Specified by:

receive in class MessageQueue

Parameters:

correlationId - (optional) transaction id to trace execution through call chain.

waitTimeout - a timeout in milliseconds to wait for a message to come.

Returns:

a message envelop object.

renewLock

public void renewLock(MessageEnvelop message,
                      long lockTimeout)

Renews a lock on a message that makes it invisible from other receivers in the queue. This method is usually used to extend the message processing time.

Specified by:

renewLock in interface IMessageQueue

Specified by:

renewLock in class MessageQueue

Parameters:

message - a message to extend its lock.

lockTimeout - a locking timeout in milliseconds.

abandon

public void abandon(MessageEnvelop message)

Returnes message into the queue and makes it available for all subscribers to receive it again. This method is usually used to return a message which could not be processed at the moment to repeat the attempt. Messages that cause unrecoverable errors shall be removed permanently or/and send to dead letter queue.

Specified by:

abandon in interface IMessageQueue

Specified by:

abandon in class MessageQueue

Parameters:

message - a message to return.

complete

public void complete(MessageEnvelop message)

Permanently removes a message from the queue. This method is usually used to remove the message after successful processing.

Specified by:

complete in interface IMessageQueue

Specified by:

complete in class MessageQueue

Parameters:

message - a message to remove.

moveToDeadLetter

public void moveToDeadLetter(MessageEnvelop message)

Permanently removes a message from the queue and sends it to dead letter queue.

Specified by:

moveToDeadLetter in interface IMessageQueue

Specified by:

moveToDeadLetter in class MessageQueue

Parameters:

message - a message to be removed.

listen

public void listen(String correlationId,
                   IMessageReceiver receiver)

Listens for incoming messages and blocks the current thread until queue is closed.

Specified by:

listen in interface IMessageQueue

Specified by:

listen in class MessageQueue

Parameters:

correlationId - (optional) transaction id to trace execution through call chain.

receiver - a receiver to receive incoming messages.

See Also:

IMessageReceiver, receive(String, long)

endListen

public void endListen(String correlationId)

Ends listening for incoming messages. When this method is call listen() unblocks the thread and execution continues.

Specified by:

endListen in interface IMessageQueue

Specified by:

endListen in class MessageQueue

Parameters:

correlationId - (optional) transaction id to trace execution through call chain.

toString

public String toString()

Override toString() method, string representation of queue.

Overrides:

toString in class MessageQueue

Returns:

queue name