HPlogo NetIPC 3000/XL Programmer's Reference Manual: HP 3000 MPE/iX Computer Systems > Chapter 3 NetIPC Intrinsics

IPCGIVE
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Gives away a VC socket or call socket descriptor, making it available for use by other processes.

Syntax

IPCGIVE  (descriptor,givename,nlen,flags,result)

Parameters

descriptor (input)

32-bit integer, by value. The VC socket or call socket descriptor to be given away.

givename (input/output)

Character array, by reference. A name which will be temporarily assigned to the specified socket. The process which obtains the socket must request it by this name. If the nlen (name length) parameter is zero, an 8-character name is randomly assigned and returned in the givename parameter. If the name is supplied by the user, it must be no longer than 16 characters.

nlen (input)

32-bit integer, by value. Length in bytes of the specified name. If the value is zero, the NetIPC facility will assign the name.

flags

32 bits, by reference. A bit representation of various options. No flags are currently defined for this intrinsic.

result (output)

32-bit integer, by reference. The error code returned; zero if no error.

Description

A process can invoke IPCGIVE to give away a VC socket or call socket descriptor that it owns. Another process at the same node must then "get" the descriptor in order to use it. For example, Process A at node X can give away a VC socket descriptor. Process B, also at node X, may get the descriptor and send data over the connection that Process A has previously established with process C at node Z. Because Process B "got" the endpoint of a previously established connection, it does not need to create its own call socket and engage in the NetIPC connection dialogue in order to communicate with Process C.

All the parameters are required.

When a socket is given away, it is assigned a new, temporary name. This name is either specified by the user or assigned by the NetIPC facility. It continues to exist only until the socket is obtained by another process or destroyed. The other process uses this name in a call to IPCGET, not IPCLOOKUP. However, the syntax of the name is the same as it is for other intrinsics permitting socket name parameters. Therefore it is possible to use a socket's "well-known" name — a name bound to the socket and known to other processes — in the IPCGIVE and IPCGET intrinsics.

Once a process has given away a socket, it no longer has access to the VC socket (or call socket) descriptor specified. If a process expires after giving away a socket, and no other process has obtained it, the VC socket or call socket will be destroyed.

Also, after a socket has been given away, it is the responsibility of the new owning process to tell other processes that the socket has been acquired. Other processes will then know who is receiving the data they send.

Condition codes returned by this intrinsic are:

  • CCE — Succeeded.

  • CCL — Failed.

  • CCG — Not returned by this intrinsic.

This intrinsic cannot be called in split stack mode.



IPCGET
  		 


IPCLOOKUP  
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