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4/8/2010

This method returns the message at the current cursor location and removes the message from the queue.

Syntax 

HRESULT ReceiveCurrent( 
  VARIANT* 
Transaction,
  VARIANT* 
WantDestinationQueue, 
  VARIANT* 
WantBody, 
  VARIANT* 
ReceiveTimeout, 
  MSMQMessage** 
ppmsg 
);

Parameters

Transaction

Optional. The following list describes the Transactionconstants:

  • MQ_NO_TRANSACTION: Specifies that the call is not part of a transaction.

  • MQ_MTS_TRANSACTION: Default. Specifies that the call is part of the current Microsoft Transaction Server (MTS) transaction.

  • MQ_XA_TRANSACTION: Specifies that the call is part of an externally coordinated, XA-compliant transaction.

WantDestinationQueue

Optional. The default is FALSE.

If TRUE, MSMQMessage.DestinationQueueInfois updated when the message is read from the queue. Setting this property to TRUE can slow the operation of the application.

WantBody

Optional. The default is TRUE.

If do not need the body of the message, set this property to FALSE to optimize the speed of the application.

ReceiveTimeout

Optional. Specifies how long, in milliseconds, Message Queuing waits for a message to arrive.

ppmsg

Current message.

Return Value

The following table describes the common return values.

Value Description

S_OK

Success

E_INVALIDARG

One or more arguments are invalid

E_NOTIMPL

The function contains no implementation

E_OUTOFMEMORY

Out of memory

Remarks

MSMQQueue.ReceiveCurrentuses the cursor created when the queue is opened to locate the message. (Do not use this method when navigating the queue using lookup identifiers.)

This method uses the cursor created when the queue is opened, and is typically used with MSMQQueue.PeekCurrentand MSMQQueue.PeekNext.

ReceiveTimeout parameter

Optional. If a timeout period is specified and a timeout occurs, a Null message object is returned to the application.

If a timeout period is not specified, the default value of ReceiveTimeout (INFINITE) forces the MSMQQueue.Peekcall to block execution until a message arrives.

WantDestinationQueue and WantBody parameters

Use the separameters to optimize the speed of the application.

Retrieving Messages Synchronously

For synchronous calls, execution is stopped until a message is retrieved from the queue or the message's timeout timer expires.

Retrieving Messages Asynchronously

The MSMQEventobject, used to read messages asynchronously, is implemented in terms of callbacks, and is limited to 64 callbacks per process.

Internally, Message Queuing uses the WaitForMultipleObjectsfunction, which is limited to 64 objects per process.

Retrieving Message in Transactions

To retrieve a message within a transaction, do one of the following:

  • Set the Transactionparameter to an MSMQTransactionobject.

  • Set the Transactionparameter to a constant described in the preceding table.

  • Use the Transactionparameter's default setting (MQ_MTS_TRANSACTION).

To guarantee that no transaction will be used (for example, if you retrieve a message from a nontransactional queue within a transactional MTS component), set Transactionto MQ_NO_TRANSACTION.

Messages cannot be retrieved from remote queues within a transaction.

Message Queuing performs the following tasks when a transaction is specified.

  • In the case of a subsequent Abort, the message is returned to its original place in the queue.

  • In the case of a Commit, a positive acknowledgment message is sent to the administration queue of the sending application. The class property of the acknowledgment message is MQMSG_CLASS_ACK_RECEIVE.

Transaction objects cannot be reused after you commit to or abort the transaction.

If you release the transaction object without calling Commitor Abort, the transaction is aborted.

Opening queues

To retrieve messages, the queue must be opened with receive access (Access = MQ_RECEIVE_ACCESS). Messages retrieved from a queue are also removed from the queue.

Opening a queue requires a direct connection to the computer where the queue resides. You cannot retrieve messages from a queue that resides on a computer that has no direct connection to the computer where your application is running.

Responding to Messages

The receiving application can determine if the sending application expects a response messages by retrieving the MSMQMessage.ResponseDestination(introduced in MSMQ 3.0) or MSMQMessage.ResponseQueueInfoproperty when reading the message.

If the property is set to Null, the sending application is not expecting a response message.

Message body type

When retrieving message, you cannot look at the type of message body included in the message. Message Queuing determines the body type based on the message's body type property. (The body type property of messages can be accessed only with Message Queuing functions.)

If the message is sent using MQSendMessage, the following situations can occur.

  • If the body type property is not set before MQSendMessageis called, the message body is treated as an array of bytes.

  • If the body type is set to an invalid body type before MQSendMessageis called, the message can be retrieved, but an error occurs when you try to read the message body.

Equivalent Function

When using function calls, use MQReceiveMessageto retrieve messages in the queue. To retrieve messages using this function, set the dwActionparameter to the appropriate value.

Requirements

Header mqoai.h
Library mqoa.lib
Windows Embedded CE Windows CE .NET 4.0 and later
Windows Mobile Windows Mobile Version 5.0 and later