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

20 Chapter1
NetIPC Fundamentals
NetIPC Concepts
resulting destination descriptor, like a telephone number, is then
used to direct a caller to a particular destination.
Descriptors
NetIPC processes reference three types of descriptors: 1) call socket
descriptors, 2) destination descriptors, and 3) virtual circuit socket
descriptors. Descriptors are returned to processes when certain NetIPC
calls are invoked (see Table 1-1). The following is an explanation of the
descriptors, the NetIPC call, or calls, that are used to obtain them, and
the terminology used to refer to these descriptors in the syntax and
parameter statements:
• Call Socket Descriptor. A call socket descriptor describes a call
socket. A process obtains a call socket descriptor by invoking
IPCCREATE (to create a call socket) or IPCGET (to get a descriptor
given away by another process). When a call socket descriptor is
obtained with either method, the call socket is said to be owned by
the calling process. The term
calldesc refers to a call socket
descriptor parameter.
• Destination Descriptor. A destination descriptor describes a
destination socket. The descriptor points to addressing information
that is used to direct requests to a specified call socket at a specified
node. A process obtains a destination descriptor by invoking the
command IPCLOOKUP (to look up the name of a call socket in a
specific socket registry) or IPCDEST (if the address of the destination
call socket is known). The term
destdesc refers to a destination
descriptor parameter.
• VC Socket Descriptor. A VC socket descriptor describes a VC
socket. A VC socket is the endpoint of a virtual circuit connection
between two processes. A VC socket descriptor is returned by
IPCCONNECT and IPCRECVCN during the creation of a connection
between two call sockets. A process can also obtain a VC socket
descriptor given away by another process by invoking IPCGET. The
term
vcdesc refers to a VC socket descriptor parameter.