Learn something new every day More Info... by email
Sockets, whether used in Linux® or another operating system (OS), are made to establish a connection between a client program and a server. This allows the two programs to share information, which is important for many processes. There are many opportunities to mess up Linux® socket programming at any stage, but these tips can make the Linux® socket programming task easier. This will include the proper way of coding the client and server connection, standardized ports, and using the right socket type and domain.
Programming the client and server sides of the socket connection involve different processes. On the client side, the first action is to create a socket via “socket().” After this, the programmer must use the “connect()” command to connect to the server. Finally, he or she must use the “read()” and “write()” commands to send and receive data through the socket from the server.
On the server side, it starts the same way, with the “socket()” command. After this, the server must bind to the client with “bind()". The server must “listen()” to the client to ensure the socket is connected and the client is responding. When the server verifies the connection, the programmer just ends the Linux® socket programming with the “accept()” command. If either the client or server side of the Linux® socket programming is done in a different order, or if anything is skipped, the socket will either refuse the connection or will not display any information.
To connect to a server, the client must know the server’s port. There are some standard ports, such as Port 21 for file transfer protocol (FTP), but the port is different for each program. One must ensure the port is right or the client may connect with the wrong server.
In Linux® socket programming, the programmer can specify several types of sockets, but two main sockets are used: datagram and stream. Datagram grabs the message or information from one side of the socket connection and reads it all at once. Stream reads the message as it is made, character by character. Stream is more secure, but datagram is better for servers that deliver many text-based messages.
Sometimes in Linux® socket programming, a socket is refused even though all the programming is done correctly. This is often because the sockets for the client and the server have conflicting address domains. For the socket to properly connect, both the server and client must be on the same domain, such as the Internet domain.