MQOPEN()

Purpose

Open a pointer to a message queue

Syntax

MQOPEN(<expC> [,<expN>])

See Also

MQCLOSE(), MQCREATE(), MQCURMSGS(), MQRECEIVE(), MQSEND()

Description

The MQOPEN() function opens an existing message queue. It returns a numeric pointer when the queue is opened successfully, or a -1 if unsuccessful. The <expC> is the name of the queue to open. Since the pointer is required to identify an open queue to other messaging functions, always assign the return value to a memory variable. The optional <expN> determines the queue access mode:

<expN>	Access Mode
Unspecified	Read only access
0	Read only access
1	Write only access
2	Read/Write access

The MQCLOSE() function is used to close a queue which has been opened with MQOPEN() or MQCREATE().

For more examples of handling message queues, please see the examples/mqueue programs in the software distribution.

Example

mqdes=mqopen("/myqueue")
if (mqdes < 0)
    messagebox(strerror()+",errno="+alltrim(str(error())))
    return
endif
do while (mqcurmsgs(mqdes) > 0)
    mstr=mqreceive(mqdes)
    if (empty(mstr))
        messagebox(strerror()+",errno="+alltrim(str(error())))
        return
    endif
    messagebox(mstr)
enddo
mqclose(mqdes)

Products

Recital, Recital Server