MessageQueue.Receive Method (TimeSpan, MessageQueueTransaction)
Assembly: System.Messaging (in system.messaging.dll)
public Message Receive ( TimeSpan timeout, MessageQueueTransaction transaction )
public function Receive ( timeout : TimeSpan, transaction : MessageQueueTransaction ) : Message
Parameters
- timeout
A TimeSpan that indicates the time to wait until a new message is available for inspection.
- transaction
The MessageQueueTransaction object.
Return Value
A Message that references the first message available in the queue.| Exception type | Condition |
|---|---|
| The value specified for the timeout parameter is not valid, possibly timeout is less than TimeSpan.Zero or greater than MessageQueue.InfiniteTimeout. | |
| A message did not arrive in the queue before the time-out expired. -or- The queue is non-transactional. -or- An error occurred when accessing a Message Queuing method. |
Use this overload to receive a message from a transactional queue using the internal transaction context defined by the transaction parameter, and return within a specified period of time if there are no messages in the queue.
The Receive method allows for the synchronous reading of a message, thereby removing it from the queue. Subsequent calls to Receive will return the messages that follow in the queue.
Because this method is called on a transactional queue, the message that is received would be returned to the queue if the transaction is aborted. The message is not permanently removed from the queue until the transaction is committed.
To read the first message in a queue without removing it from the queue, use the Peek method. The Peek method always returns the first message in the queue, so subsequent calls to the method return the same message unless a higher priority message arrives in the queue. There is no transaction context associated with a message returned by a call to Peek. Because Peek does not remove any messages in the queue, there would be nothing to roll back by a call to Abort.
Use a call to Receive when it is acceptable for the current thread to be blocked while it waits for a message to arrive in the queue. The thread will be blocked for the given period of time, or indefinitely if you specified the value InfiniteTimeout for the timeout parameter. If the application processing should continue without waiting for a message, consider using the asynchronous method, BeginReceive.
The following table shows whether this method is available in various Workgroup modes.
| Workgroup mode | Available |
|---|---|
| Local computer | Yes |
| Local computer and direct format name | Yes |
| Remote computer | No |
| Remote computer and direct format name | Yes |
The following code example demonstrates the use of this method.
using System; using System.Messaging; namespace MyProject { /// <summary> /// Provides a container class for the example. /// </summary> public class MyNewQueue { //************************************************** // Provides an entry point into the application. // // This example sends and receives a message from // a transactional queue. //************************************************** public static void Main() { // Create a new instance of the class. MyNewQueue myNewQueue = new MyNewQueue(); // Send a message to a queue. myNewQueue.SendMessageTransactional(); // Receive a message from a queue. myNewQueue.ReceiveMessageTransactional(); return; } //************************************************** // Sends a message to a transactional queue. //************************************************** public void SendMessageTransactional() { // Connect to a queue on the local computer. MessageQueue myQueue = new MessageQueue(".\\myTransactionalQueue"); // Send a message to the queue. if (myQueue.Transactional == true) { // Create a transaction. MessageQueueTransaction myTransaction = new MessageQueueTransaction(); // Begin the transaction. myTransaction.Begin(); // Send the message. myQueue.Send("My Message Data.", myTransaction); // Commit the transaction. myTransaction.Commit(); } return; } //************************************************** // Receives a message from the transactional queue. //************************************************** public void ReceiveMessageTransactional() { // Connect to a transactional queue on the local computer. MessageQueue myQueue = new MessageQueue(".\\myTransactionalQueue"); // Set the formatter. myQueue.Formatter = new XmlMessageFormatter(new Type[] {typeof(String)}); // Create a transaction. MessageQueueTransaction myTransaction = new MessageQueueTransaction(); try { // Begin the transaction. myTransaction.Begin(); // Receive the message. // Wait five seconds for a message to arrive. Message myMessage = myQueue.Receive(new TimeSpan(0,0,5), myTransaction); String myOrder = (String)myMessage.Body; // Display message information. Console.WriteLine(myOrder); // Commit the transaction. myTransaction.Commit(); } catch (MessageQueueException e) { // Handle nontransactional queues. if (e.MessageQueueErrorCode == MessageQueueErrorCode.TransactionUsage) { Console.WriteLine("Queue is not transactional."); } // Handle no message arriving in the queue. else if (e.MessageQueueErrorCode == MessageQueueErrorCode.IOTimeout) { Console.WriteLine("No message in queue."); } // Else catch other sources of MessageQueueException. // Roll back the transaction. myTransaction.Abort(); } // Catch other exceptions as necessary, such as // InvalidOperationException, thrown when the formatter // cannot deserialize the message. return; } } }
package MyProject;
import System.*;
import System.Messaging.*;
/// <summary>
/// Provides a container class for the example.
/// </summary>
public class MyNewQueue
{
//**************************************************
// Provides an entry point into the application.
//
// This example sends and receives a message from
// a transactional queue.
//**************************************************
public static void main(String[] args)
{
// Create a new instance of the class.
MyNewQueue myNewQueue = new MyNewQueue();
// Send a message to a queue.
myNewQueue.SendMessageTransactional();
// Receive a message from a queue.
myNewQueue.ReceiveMessageTransactional();
return;
} //main
//**************************************************
// Sends a message to a transactional queue.
//**************************************************
public void SendMessageTransactional()
{
// Connect to a queue on the local computer.
MessageQueue myQueue = new MessageQueue(".\\myTransactionalQueue");
// Send a message to the queue.
if (myQueue.get_Transactional() == true) {
myQueue.Send("My Message Data.", new MessageQueueTransaction());
}
return;
} //SendMessageTransactional
//**************************************************
// Receives a message from the transactional queue.
//**************************************************
public void ReceiveMessageTransactional()
{
// Connect to a transactional queue on the local computer.
MessageQueue myQueue = new MessageQueue(".\\myTransactionalQueue");
// Set the formatter.
myQueue.set_Formatter(new XmlMessageFormatter(new Type[]
{ String.class.ToType() }));
// Create a transaction.
MessageQueueTransaction myTransaction = new MessageQueueTransaction();
try {
// Begin the transaction.
myTransaction.Begin();
// Receive the message.
// Wait five seconds for a message to arrive.
Message myMessage = myQueue.Receive(new TimeSpan(0, 0, 5),
myTransaction);
String myOrder = (String)(myMessage.get_Body());
// Display message information.
Console.WriteLine(myOrder);
// Commit the transaction.
myTransaction.Commit();
}
catch (MessageQueueException e) {
// Handle nontransactional queues.
if (e.get_MessageQueueErrorCode().
Equals(MessageQueueErrorCode.TransactionUsage)) {
Console.WriteLine("Queue is not transactional.");
}
// Handle no message arriving in the queue.
else {
if (e.get_MessageQueueErrorCode().
Equals(MessageQueueErrorCode.IOTimeout)) {
Console.WriteLine("No message in queue.");
}
}
// Else catch other sources of MessageQueueException.
// Roll back the transaction.
myTransaction.Abort();
}
// Catch other exceptions as necessary, such as
// InvalidOperationException, thrown when the formatter
// cannot deserialize the message.
return;
} //ReceiveMessageTransactional
} //MyNewQueue
Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.
