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

Writing Pathway Servers

NonStop TS/MP Pathsend and Server Programming Manual–132500

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Writing Context-Sensitive Servers

If you are writing a context-sensitive Pathway server, you must follow the guidelines in

Basic Pathway Server Programming earlier in this section and also perform additional

programming tasks. This subsection describes these additional tasks and other

considerations for programming context-sensitive servers.

When you use context-sensitive Pathway servers, the requester and server must be

designed to work together. The context-sensitive Pathsend procedure calls used by the

requester, described in Section 3, Writing Pathsend Requesters

, and Section 5, Pathsend

Procedure Call Reference, convey dialog information to the server, and the server

conveys dialog information in its reply.

Functions of a Context-Sensitive Server

In addition to the functions performed by all Pathway servers, a context-sensitive server

must do the following:

•

Detect a newly established dialog

•

Receive, service, and reply to messages associated with a dialog

•

Correlate messages with a dialog

•

Continue a dialog

•

Terminate a dialog

•

Abort a dialog

•

Detect an aborted dialog

It is simpler to code a context-sensitive server if you allow only one dialog at a time.

To impose this restriction, you must configure the server class with a MAXLINKS value

of 1. If MAXLINKS is set to a value other than 1, you must code your server to save

multiple dialog contexts and to switch context, if needed, on each incoming request.

When a server receives a message on $RECEIVE, it checks dialog flag bits <12:13>

returned by the file-system procedure FILE_GETRECEIVEINFO_ or the Common

Run-Time Environment (CRE) procedure CRE_Receive_Read_ to determine whether

this is the first message of a new dialog or a message within an existing dialog. A value

of zero in these two bits indicates a context-free send operation. In addition, the server

can check dialog flag bit 14 to determine the model used by the requester for associating

transactions with dialogs.

Note. The SCREEN COBOL language does not support context sensitivity; therefore, to take

advantage of context sensitivity, you must use either a Pathsend requester or a GDSX

front-end process that uses the GDSX pseudo Pathsend procedures.