Sunday, November 28, 2010

Socket Programming

Sockets are interfaces that can "plug into" each other over a network. Once so "plugged in", the programs so connected communicate. A "server" program is exposed via a socket connected to a certain /etc/services port number. A "client" program can then connect its own socket to the server's socket, at which time the client program's writes to the socket are read as stdin to the server program, and stdout from the server program are read from the client's socket reads.

Before a user process can perform I/O operations, it calls Open to specify and obtain permissions for the file or device to be used. Once an object has been opened, the user process makes one or more calls to Read or Write data. Read reads data from the object and transfers it to the user process, while Write transfers data from the user process to the object. After all transfer operations are complete, the user process calls Close to inform the operating system that it has finished using that object.

 

For Reference

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