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

Glossary
NonStop TS/MP Pathsend and Server Programming Manual–132500
Glossary-4
context
context. Information required by a server to process the current request in an exchange of
multiple request and reply messages: for example, identification of the last item
processed. See also context-free server and terminal context.
context-free server. A server that does not retain any information about the processing of
previous requests. A context-free server accepts a single message from a requester,
performs the requested tasks, and issues a single reply to respond to the requester. After
the reply message is issued, the server retains no information, or context, that can be
used in subsequent requests. In general, context-free servers are relatively simple to
program and can be restarted quickly, but they require the requester to pass context
information to the server on each request. Servers handling requests from Pathsend
requesters can be either context-free or context-sensitive, but servers servicing requests
from SCREEN COBOL requesters must be context-free. A context-free server is
analogous to a NonStop TUXEDO request/response server. Tandem subsystems are
context-free servers; therefore, management applications using the Subsystem
Programmatic Interface (SPI) to communicate with Tandem subsystems must pass back
context information in continuation requests. See also context, context-sensitive server,
and Subsystem Programmatic Interface (SPI).
context-sensitive server. A server that retains information about the processing of previous
requests. A context-sensitive Pathway server can engage in a multiple-message
communication, or dialog, with a requester. Because context-sensitive servers must
maintain message context for the dialog, they are more complex to program than
context-free servers. They typically have longer restart times because they must recover
the requester context. See also context and context-free server.
context sensitivity. The ability of a requester to exchange a series of multiple request and
reply messages (that is, a dialog) with a particular server process. See also context-
sensitive server and dialog.
conversation. See dialog.
conversational mode. (1) A terminal operating mode in which data is read from the terminal
and displayed on the terminal screen one line at a time. See also block mode and
intelligent mode. (2) The mode of communication that enables an ongoing dialog
between a client (or requester) and a server. Data is sent and received in an iterating
fashion without return to the transaction monitor until the application dialog is
completed. Multiple messages can be exchanged between the client and server
participating in the communication. See also conversational server.
conversational model. A model for requester-server communication that enables an ongoing
dialog between a client (or requester) and a server. Multiple messages can be exchanged
between the client and server process before control is returned to the transaction
monitor. See also request/response model and conversational server.
conversational server. A server that offers conversational services and can participate in a
conversation, or dialog, with a client; that is, a context-sensitive server. See also
conversational mode (definition 2), request/response server, and context-sensitive server.