Communicating With a Process
Initiating and Communicating With Processes
107365 Tandem Computers Incorporated 5–5
3. Send a command.
4. Wait for output from the process (a WRITE operation).
5. Based on the reply, decide upon the next action and either go back to Step 2 or
continue to Step 6.
6. When finished, send an exit message to the process.
The following facilities support this type of operation.
INLINE
INV and OUTV (sometimes called implicit servers)
#SERVER
Define Process (part of ViewPoint)
A second communication method uses $RECEIVE to communicate with processes,
devices, and files, following these steps:
1. Open the process prior to sending a request.
2. Send a request to the process.
3. Receive a reply from the process.
4. Based on the reply, decide upon the next action and either go back to Step 2 or
continue to Step 5.
5. When finished, close the process.
The #REQUESTER, #APPEND(V), #EXTRACT(V), and #WAIT built-in functions
support this type of communication.
There is also a third communication method that allows TACL to run as a server
process. Section 6 , “Running TACL as a Server,” describes this method.
The following subsections describe these communication mechanisms and describe
how to send a request, retrieve results, handle errors, and terminate communication.
Note If TACL attempts to open a process for communication at the same time that process is attempting to
open TACL for communication, a deadlock condition can occur. Coordinate your use of communication
mechanisms to avoid simultaneous open operations.
TACL cannot intercept messages from processes that are in block mode.
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