TS/MP Pathsend and Server Programming Manual (G06.24+, H06.03+)

Designing Your Application
NonStop TS/MP Pathsend and Server Programming Manual–132500
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Pathsend Requesters
•
Fault tolerance through process pairs
•
Multithreading and multitasking
•
Expanded I/O editing support for data streams from intelligent devices
For information about designing and coding IDS requesters, refer to the Pathway/TS
TCP and Terminal Programming Guide.
Pathsend Requesters
As an alternative to writing SCREEN COBOL requesters, you can write Pathsend
requesters in C, C++, COBOL85, Pascal, TAL, or pTAL. In such requesters, you use
Pathsend procedure calls to communicate with Pathway servers. The LINKMON
process manages links to your server processes on behalf of Pathsend requesters.
Design Considerations
Pathsend requesters are a good choice for your applications if you need to do the
following:
•
Take a high volume of transactions from a limited number of devices. In this
scenario, there are relatively few requester processes, the requesters are busy, and
configuration and management is minimal.
•
Access servers that are shared by Pathway requesters and applications other than
OLTP applications: for example, a security checking server or a logging server. If
such servers are used infrequently or if the workload varies, server processes can be
automatically deleted when not needed and restarted through the PATHMON
process when needed again.
•
Access servers from environments containing a mix of online transaction processing
and batch processing: that is, environments where the same set of servers handle
both online requests and requests from batch applications such as NetBatch Plus
processes.
•
Write nested servers, which act as requesters by making requests to servers in other
server classes, perhaps server classes managed by a different PATHMON process.
•
Write context-sensitive servers, which are discussed later in this section under
“Designing Server Programs.”
Pathsend procedure calls give you more flexibility than WRITEREAD calls for server-
to-server communication. The application gets all the advantages of server classes,
including advantages not readily available with WRITEREAD; for example, load
balancing, adjusting the number of servers to fit response-time requirements, and
configuration and operations management. You can use the Pathsend procedure calls in
C, C++, COBOL85, Pascal, TAL, and pTAL programs.
The Pathsend procedures and the LINKMON process, however, do not provide
multithreading, fault tolerance, device configuration, or operations management for
requesters. Therefore, if you need these capabilities in a Pathsend requester, you must
provide the programming for them.