Socket programming

A socket is a communications connection point (endpoint) that you can name and address in a network.

The processes that use a socket can reside on the same system or on different systems on different networks. Sockets are useful for both stand-alone and network applications. Sockets allow you to exchange information between processes on the same machine or across a network, distribute work to the most efficient machine, and they easily allow access to centralized data. Socket application program interfaces (APIs) are the network standard for TCP/IP. A wide range of operating systems support socket APIs. i5/OS™ sockets support multiple transport and networking protocols. Socket system functions and the socket network functions are threadsafe.

Socket programming shows how to use socket APIs to establish communication links between remote and local processes. Programmers who use Integrated Language Environment^® (ILE) C can use the information to develop socket applications. You can also code to the sockets API from other ILE languages, such as RPG.

Java™ also supports a socket programming interface.

• What's new for V5R4
  This topic highlights some changes to the Socket programming for V5R4.
• Printable PDFs
  Use this to view and print a PDF of this information.
• Prerequisites for socket programming
  Before writing socket applications, you must first complete these steps.
• How sockets work
  Sockets are commonly used for client/server interaction. Typical system configuration places the server on one machine, with the clients on other machines. The clients connect to the server, exchange information, and then disconnect.
• Socket characteristics
  Sockets share some common characteristics.
• Basic socket design
  This topic provides examples of sockets programs that use the most basic design.
• Advanced socket concepts
  Advanced socket concepts go beyond a general discussion of what sockets are and how they work. They provide ways to design socket applications for larger and more complex networks.
• Socket scenario: Create an application to accept IPv4 and IPv6 clients
  This topic describes a typical situation in which you might want to use the AF_INET6 address family.
• Socket application design recommendations
  Before working with socket applications, assess the functional requirements, goals, and needs of the socket application.
• Examples: Socket application designs
  These examples provide many sample programs that illustrate the more advanced socket concepts. You can use these sample programs to create your own applications that complete a similar task.
• Xsockets tool
  The Xsockets tool is one of the many tools that are shipped with the iSeries™. All tools are stored in the QUSRTOOL library. The Xsockets tool allows programmers to interactively work with socket APIs.
• Serviceability tools
  As the use of sockets and secure sockets continues to grow to accommodate e-business applications and servers, the current serviceability tools need to keep up with this demand.