Socket programming is a programming scheme in which sockets are used and manipulated to create a connection between software. Sockets are used to connect software between different computers or within the same computer so that programs can share data. Socket programming is used with instant messaging, Internet browsers, file sharing programs, and anything that forces the computer to connect to a system. Most sockets are scheduled automatically, but some operating systems (OS) put this responsibility in the hands of the user.
Sockets, whether used in Linux® or another operating system (OS), are made to establish a connection between a client program and a server.
Socket programming involves using a list of commands to connect a socket from one computer to another. For example, for an instant messaging program to work, it must be connected to a second computer. To make this connection, a plug is used. By forging the connection, the two computers can now connect and communicate with each other.
Peer-to-Peer (P2P) programs are special cases when it comes to socket programming. Most programs act as either a client or a server. A P2P program acts as both, whereby users can download files from one person while files are being downloaded from the user at the same time.
While most socket programming is used for two computers to interact, it is also useful for two programs on the same computer. Known as interprocessing, this allows one program to take information from another program and use it. For example, if a program is a slideshow maker and it needs information from a video program to play videos on the slide, then a connector is created to connect the slideshow and video programs. Interprocessing is common, but not as common as using sockets between two computers.
When using socket programming, the programmer and user must remember that sockets are bidirectional. This means that the two computers can communicate while getting data from each other. Opening a computer to another system can be dangerous, because the other side will be able to launch an attack if the user is malicious. However, this is rare, and connecting a socket to another system is generally safe.
Sockets are usually created automatically by the operating system or with limited programming. On OS interfaces where the command line is frequently used, the user will often have to manually forge sockets. This forces the user to know some basic socket programming in order to make these important connections. If the socket is not created, the computer will not be able to communicate with other systems, limiting the usefulness of the computer.
