Advanced Perl Programming

Chapter 12. Networking with Sockets

I plugged my phone in where the blender used to be. I called someone. They went “Aaaaahhh...”

—Steven Wright

Programs can communicate with each other in a variety of ways. They can use files, anonymous/named pipes, System V interprocess messaging primitives, BSD sockets, and TLI (Transport Layer Interface). Socket and TLI communications come under the purview of “networking,” a step up from the other IPC (interprocess communication) mechanisms, because they don’t constrain the communicating processes to be on the same machine. This chapter provides a primer on socket communications and builds simple client/server configurations using Graham Barr’s IO library (part of the standard Perl distribution). This knowledge is put to use in the next chapter, where we build an asynchronous message passing module, and another for doing remote procedure calls (RPC).

Networking is the second of four important technologies that we discuss in this book; the others are user interfaces, persistence, and code generation. This chapter, like the other three, is as much about the technology as it is about Perl’s support for it. Andrew Tanenbaum’s textbook on computer networks [Section 12.7] is a wonderful introduction to computer networking. (I also rate it as one of the best computer books ever written.) This chapter provides just enough introduction to networks to work with Perl, sockets, and TCP/IP.

Networking Primer

Mail (paper and electronic) and telephones are ...