HP TACL User Manual

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.

HP TACL Specifications

General

Name	HP TACL
Purpose	Task automation, system management, and application control
Category	Software
Platform	HP NonStop
Type	Scripting language
Developer	Hewlett-Packard

Summary

Section 1 An Overview of TACL

Running the Examples in This Manual

Instructions for executing manual examples, including setting required variables.

About This Manual

Section 2 Developing TACL Programs

Processing Character Data

Covers tasks like constructing text strings, analyzing output, and manipulating characters.

Debugging TACL Programs

Introduces the TACL debugger for step-by-step execution and variable examination.

Section 3 Developing TACL Routines

Processing Arguments

Details how routines handle arguments using #ARGUMENT, including options and alternatives.

Writing an Exception Handler

Explains handling events like BREAK keys or TACL errors using exception handlers.

4 Accessing Files

#REQUESTER Operation

Describes the #REQUESTER function for opening files and initiating I/O operations.

Requesting Waited Reads

Explains opening files for waited read operations using #REQUESTER.

5 Initiating and Communicating With Processes

Initiating a Process: RUN and #NEWPROCESS

Covers starting processes using RUN and #NEWPROCESS, including startup options.

Using the INLINE Facility

Using INV and OUTV

Using $RECEIVE

Using #SERVER

6 Running TACL as a Server

Running a TACL Process as a Server

Explains making a TACL process a server by establishing its IN file as $RECEIVE.

Running TACL Code as a Server

Details providing TACL code for a TACL-server process using #INPUTV and #REPLYV.

Using TACL as a Pathway Server

Describes creating a Pathway environment with TCP and TACL servers to process requests.

7 Using Programmatic Interfaces

Overview of SPI and EMS

Using SPI

Using EMS

8 Example of a System Management Program

Monitoring System Operation