CMTransport.SendRequest

Method

Visual Basic

Overrides Public Function SendRequest (
    ByVal request As Message,
    ByVal timeout As Double )
  As Message

C#

public override Message SendRequest (
    Message request,
    double timeout );

Purpose

Send a labeled request message and wait for a reply.

Blocking can Stall Event Dispatch

Warning

This call blocks all other activity on its program thread. If appropriate, programmers must ensure that other threads continue dispatching events on its queues.

Parameter	Description
`request`	Send this request message. Wildcard subjects are illegal.
`timeout`	Maximum time (in seconds) that this call can block while waiting for a reply.

Parameter

Description

request

Send this request message.

Wildcard subjects are illegal.

timeout

Maximum time (in seconds) that this call can block while waiting for a reply.

Remarks

Programs that receive and process the request message cannot determine that the sender has blocked until a reply arrives.

The sender and receiver must already have a certified delivery agreement, otherwise the request is not certified.

The request message must have a valid destination subject; see SendSubject.

A certified request does not necessarily imply a certified reply; the replying program determines the type of reply message that it sends.

Operation

This method operates in several synchronous steps:

Procedure

1. Create a CMListener that listens for messages on the reply subject of msg.

2. Label and send the outbound message.

Block until the listener receives a reply; if the time limit expires before a reply arrives, then return null. (The reply event uses a private queue that is not accessible to the program.)

Return the reply message as the value of the method call.