SOCKET_INIT Function

Binds a socket to a specified port that is designated to listen for client connections.

Usage

socket = SOCKET_INIT(port)

Input Parameters

port—The port number on which the server will listen. You can call SOCKET_INIT with a port number of 0 (zero), which lets your operating system pick an available port.

Keywords

None.

Returned Value

socket—On success, returns a socket handle; on failure, returns one of the following values:

–2—Error creating the socket.

–3—Error binding the socket.

–4—Error on the listen() command.

Discussion

You must call this routine in a server program to specify which port to listen on for client connections.

The port number is usually a standard, or previously agreed upon, port that clients use to contact a server. For example, by convention, most Web servers listen for connections on port 80. Most hosts have ports numbered between 1 and 65,535. Typically, ports 0 to 1024 are reserved and only available to someone with administrator or super user privileges.

The returned socket handle is used by other SOCKET_* routines to identify a particular socket connection.

It is good practice to close the socket handle when you are finished with it.

Example

In this simple server program, a socket is bound to port 1500, which is the port that the client program uses to contact the server.

PRO SERVER

   port = 1500

   socket = SOCKET_INIT(port)

   connection = SOCKET_ACCEPT(socket)

   data = BYTARR(15)

   nbytes = SOCKET_READ(connection,data)

   PRINT, 'SERVER received: ', STRING(data)

   SOCKET_CLOSE, connection

   SOCKET_CLOSE, socket

END