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

Introduction to Pathway Application Programming

NonStop TS/MP Pathsend and Server Programming Manual–132500

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Servers and Server Classes

You can write Pathway server programs in C, C++, COBOL85, Pascal, the Transaction

Application Language (TAL), the Portable Transaction Application Language (pTAL),

FORTRAN, or Extended BASIC in the Guardian environment. Alternatively, you can

write Pathway server programs in C or COBOL85 in the NonStop Kernel Open System

Services (OSS) environment; you must program such servers to read the Guardian

$RECEIVE file as described in the Open System Services Programmer’s Guide. In both

cases, you configure and manage the servers using the PATHCOM interactive interface

or the Pathway management programming interface (based on the Subsystem

Programmatic Interface, or SPI) in the Guardian environment.

The same server programs, whether developed in the Guardian environment or in the

OSS environment, can be used with several different requester and client interfaces.

These interfaces include SCREEN COBOL, the Pathsend procedures, the Remote Server

Call (RSC) interface, and the Pathway Open Environment Toolkit (POET).

The Pathway environment provides the feature of server classes. A server class is a

collection of replicated Pathway server processes. All server processes in a server class

provide the same set of functions; that is, they execute the same program.

Server Processes

Server processes provide the following benefits:

•

Server processes help ensure transaction integrity and, therefore, the integrity of the

database.

•

Server code can be reused by many requester programs, and you can separate

presentation services from database functions.

•

You can control which transactions can be performed on your node. You can control

the logic of the servers, database names, disk names, and so on.

•

In distributed environments, server processes provide high performance by allowing

you to use remote servers instead of performing multiple remote I/O operations,

placing transaction processing close to system resources.

Server Classes

Server classes provide the following benefits:

•

You can minimize use of system resources—for example, processes and file opens—

because server classes are shared and highly utilized.

•

You can maximize performance because server classes allow multiple copies of

server processes to run concurrently in multiple processors.

•

Based on configuration settings determined by the system manager or operator, the

PATHMON process can dynamically create additional server processes within the

server class to maintain acceptable throughput as the workload increases.