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Sending and Receiving Messages
Once the BEA Tuxedo system establishes a conversational connection, communication between the initiator and subordinate is accomplished using send and receive calls. The process with control of the connection can send messages using the tpsend(3c) function; the process without control can receive messages using the tprecv(3c) function.
Note: Initially, the originator (that is, the client) decides which process has control using the TPSENDONLY or TPRECVONLY flag value of the tpconnect() call. TPSENDONLY specifies that control is being retained by the originator; TPRECVONLY, that control is being passed to the called service.
Sending Messages
To send a message, use the tpsend(3c) function with the following signature.
int
tpsend(int cd, char *data, long len, long flags, long *revent)
The following table describes the arguments to the tpsend() function.
tpsend( ) Function Arguments
In the event of a failure, the tpsend() function returns a value of -1 and sets tperrno(5) to the appropriate error condition. For a list of possible error codes, refer to tpsend(3c) in the BEA Tuxedo C Function Reference.
You are not required to pass control each time you issue the tpsend() function. In some applications, the process authorized to issue tpsend() calls can execute as many calls as required by the current task before turning over control to the other process. In other applications, however, the logic of the program may require the same process to maintain control of the connection throughout the life of the conversation.
The following example shows how to invoke the tpsend() function.
Sending Data in Conversational Mode
if (tpsend(cd,line,0,TPRECVONLY,revent) == -1) {
(void)userlog("%s: tpsend failed tperrno %d",
argv[0],tperrno);
(void)tpabort(0);
(void)tpterm();
exit(1);
}
Receiving Messages
To receive data sent over an open connection, use the tprecv(3c) function with the following signature.
int
tprecv(int cd, char **data, long *len, long flags, long *revent)
The following table describes the arguments to the tprecv() function.
Upon success, the *data argument points to the data received and len contains the size of the buffer. If len is greater than the total size of the buffer before the call to tprecv(), the buffer size has changed and len indicates the new size. A value of 0 for the len argument indicates that no data was received.
The following example shows how to use the tprecv() function.
Receiving Data in Conversation
if (tprecv(cd,line,len,TPNOCHANGE,revent) != -1) {
(void)userlog("%s: tprecv failed tperrno %d revent %ld",
argv[0],tperrno,revent);
(void)tpabort(0);
(void)tpterm();
exit(1);
}
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Copyright © 2000 BEA Systems, Inc. All rights reserved.
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