TMF Introduction (G06.26+)

TMF Application Programming
HP NonStop TMF Introduction—522414-002
5-10
Assigning Roles to Application Modules
The roles of the modules are:
•
Requester—the module that begins and ends a transaction and specifies the kind
of work to be performed in the transaction. Typically, the requester is a SCREEN
COBOL program run by a terminal control process (TCP) in the Pathway
environment.
•
Server—the module that performs database access on behalf of the requester.
The server can be a program written in a number of application languages.
SCREEN COBOL requesters are written to run at a single terminal. With Pathway/iTS
however, copies of individual requesters can be run simultaneously on thousands of
terminals.
The server programs typically perform database input/output within a single active
transaction. They are often written in HP COBOL. To access a NonStop SQL
database, the program uses embedded SQL statements; to access an Enscribe
database, the program uses HP COBOL input/output statements.
Servers that access a NonStop SQL database can be written in languages that allow
embedded SQL statements, including C, HP COBOL, or TAL. Server programs that
access an Enscribe database can be written in C, C++, FORTRAN, HP COBOL, or
TAL.
Through the facilities of NonStop TS/MP, multiple copies of a single server program run
concurrently. Pathway/iTS simplifies the designing and coding of requester programs
by providing multithreaded functionality. TMF simplifies designing applications, as well
Figure 5-2. Modules of a Typical OLTP Pathway Application
SCREEN
TCP
Requester
...
BEGIN-TRANSACTION.
...
SEND MESSAGE MSG-OUT...
REPLY CODE...
...
END-TRANSACTION.
...
ON-ERROR-PROCEDURE.
ABORT-TRANSACTION.
...
Server
Database
Transaction
Entry
Application
Language
Program
Program
COBOL
VST025.vsd