UNIX

svc-create.

UNIX

Written by V R Sunday, 05 December 2010 16:51

The svc-create function creates a transport end point for the given nettype value in a server process.The server monitors all RPC calls to the given program and version numbers.Furthermore,for each of these RPC requests,the dispatch function is called to respond to it.

 

History of RPC.

UNIX

Written by V R Sunday, 05 December 2010 16:39

There were different implementations of RPC by different companies in the 1980s.Among them were Sun Microsystems's Open Network Computing(ONC) and Apollo Computer's Network Computing Architecture(NCA).Today,most commercial UNIX systems,such as Hewlett Packsdd's HP-UX,International Business Machines's AIX,Sun Microsystem's Sun OS 4.1x and Santa Cruz Operation's SCO UNIX all implementation RPC based on the ONC method.

However,Sun's Solaris 2.x operating system and UNIX system V.4 implement RPC based on a modified version of the ONC method.The two methods are very similar,namely,they both use external data representation format to transmit data scross networks and provide a rocgen compiler to simplify the creation of RPC applications.The two methods differ,in that the ONC-based RPC APIs are based on sockets,whereas System V.4 RPC APIs can be based on sockets or on TLI.

Sockets.

UNIX

Written by V R Sunday, 05 December 2010 16:29

Sockets may be connection-based which means sender and receiver socket addresses are pre-established before messages are passed between them or connectionless that is sender or receiver addresses must be passed along with each message sent from one process to another.There are different socket address formats,depending on the socket's assigned domain.A domain defines the socket address formats and the underlying transport protocol to be used.The common domains assigned to sockets are AF-UNIX and AF_INET.

 

Signals.

UNIX

Written by V R Sunday, 05 December 2010 16:22

Signals are triggered by events and are posted on a process to notify it that some thing has happened and requires some action.An event can be generated from a process,a user,or the UNIX kernel.For example,if a process performs a divide-by-zero mathematical operation,or dereferences a NULL pointer,the kernel will send the process a signal to interrupt it.Furthermore,if a user hits the or key at the keyboard,the kernel will send the foreground process a signal to interrupt it.Finally,a parent and its child processes can send signals to each other for process synchronization.Thus signals are the software version of hardware interrupts.Just as there are several levels of hardware interrupts on any given system,there are also different types of signals defined for different events that may occur in a UNIX system.

memory.h

UNIX

Written by V R Sunday, 05 December 2010 16:17

The header declares a set of functions for byte stream manipulations.These functions are more similar to the string functions,except that they have a more general purpose and can be used for non character string object manipulation.For example,one can use these functions to initialize,compare,and copy struct-typed objects

 

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