NetIPC 3000/XL Programmer's Reference Manual (5958-8600)

Chapter 1 35
NetIPC Fundamentals
Direct Access to Level 3 (X.25)
request for a connection can be accepted (whether or not the server
protocol relative address exists). A catch-all socket receives incoming
call requests that do not match any other given protocol relative
address. One catch-all socket can be defined for each X.25 network.
As an example, two programs communicating over an SVC can be
designated as the requester and server. Both programs need to be
running in order for communication to occur. Figure 1-10 shows the
order of NetIPC calls used for a requestor program and the X.25
packets generated as a result of the calls. Figure 1-11 describes the
order of NetIPC calls used for a server program.
NOTE Note that Figure 1-10 and Figure 1-11 do not show synchronization of
data transfer between the two programs, and do not include error
checking, or the intrinsic calls required for adding options and special
user capabilities. See example 3 in Chapter 4 , “NetIPC Examples,” of
this manual for programmatic examples of a server and requestor using
access to the X.25 protocol.
SVC Requestor Example
Figure 1-10 shows the order of NetIPC calls used for a requestor
program and the X.25 packets generated as a result of the calls. The
calls outlined in Figure 1-10 perform the following functions:
1. Create a call socket with IPCCREATE. The call socket descriptor
( calldesc ) is returned.
2. Create a destination descriptor socket (
destdesc ) with IPCDEST.
You must specify a remote protocol relative address (
protoaddr ) to
be associated with the destination descriptor.
3. Establish the virtual circuit socket with IPCCONNECT, supplying the
calldesc and destdesc created by the previous two calls.
4. Receive a response to the connection request with IPCRECV, setting
the data length parameter ( dlen ) equal to zero.
5. Send a message over the connection with IPCSEND.
6. Receive a message over the connection with IPCRECV.
7. Shutdown the connection with IPCSHUTDOWN. Cause and diagnostic
values and/or clear user data can be entered that will be included in
an X.25 clear packet sent as a result of this call.