SNAX/CNM Manual

INTRODUCTION
The Programmatic Interface
THE PROGRAMMATIC INTERFACE
From the viewpoint of a network-management application program,
$SSCP looks like a file that must be opened to establish
communication and closed to discontinue communication. Once
$SSCP is opened, the application program uses WRITEREADs to
send requests and to receive replies. Within these file-system
requests and replies are placed the CNM verbs and replies.
After the OPEN call, the program makes a SETMODE 30 call to
allow the returning of file-system replies in the order in which
$SSCP handles the file-system requests (instead of the order in
which the requests were made). The SETMODE call is recommended
but not required. Note that even when the application does
make a SETMODE 30 call, a situation can arise in which the
File System will present replies to the application in the order
in which the application issued the requests, rather than in
the order in which $SSCP completed them; should two or more
outstanding WRITEREAD requests complete before the application
issues an AWAITIO, the application will first receive a reply
to its initial request, even though $SSCP may have completed
subsequent requests before completing this initial one.
The first verb sent must be a VERB^CONNECT to complete the
connection to $SSCP. The last verb should be a VERB^DISCONNECT
to sever the connection.
Between the VERB^CONNECT and the VERB^DISCONNECT, the program
can freely send verbs to $SSCP and receive replies from $SSCP.
A maximum of three verbs can be outstanding (a verb is considered
to be outstanding when your WRITEREAD sends it to $SSCP and
$SSCP cannot provide the expected reply). By using unique tag
parameters in file-system requests that transport each verb, a
program can readily associate a reply received with the verb to
which it is an answer.
The formats of verbs and replies are given in the directories
that make up Sections 2 and 3 of this manual. The possible verbs
are summarized at the beginning of Section 2, and the possible
replies are summarized at the beginning of the Section 3. Details
of buffer formats are given in the directory entries.
The following example outlines the calls through which a network
management program APPL1 might establish communication with
$SSCP, send and receive SNA network management requests and
responses, and discontinue operation. Not shown are the manipu-
lations needed to prepare request buffers or to interpret
response buffers. For a more detailed example, see the sample
programs in Appendix A and Appendix B.
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