Unix Network Programming, Volume 1: The Sockets Networking API [Hardcover]

Chapter 12 (IPv4 and IPv6 interoperability) is extremely
valuable to slightly older developers like me that have
a fair bit of IPv4 socket programming experience but that
have not had time to plunge seriously into IPv6 socket
programming. Appendix A manages to give a fairly thorough
introduction to both IPv4 and IPv6 in less than 20 pages.
This will be very popular in universities.

The book also continues to be a living history of UNIX,
where many given API calls are not only defined and explained,
but documented as to how the API call came into being, how
many different versions of the function existed, why it got
changed and when, along with recommended do's and dont's...

All around, a must buy for developers and even
non-developers who want to understand a bit of the
the true nature of the 'plumbing' that underlies
the Internet.

After the concepts (a server 'listens' for a connection; a client initiates a connection) and basics of packets and sockets, the book presents a simple tcp server and client -- the server simply echos back whatever the client sends. Next, it discusses what can go wrong with the simple version, and presents an improved echo server that behave better when the client crashes (and likewise an improved client).

The book continues to improve on the basic client/server, including address resolution, and servers that handle multiple clients using forks, threads, non-blocking I/O. This is all I needed to learn from the book, and it's all in the first half of the book.

Particularly useful is Chapter 27, Client-Server Design Alternatives. To me it alone was worth the price of the book. Here the book discusses concurrent servers with three basic architectures:

(1) non-blocking I/O, no threads or forks (advantage: full control of resource allocation; disadvantag: complexity);

(2) spawn a thread or fork for each client (simplest implementation; potential problem of too many children);

(3) servers that pre-allocate a pool of threads or forks (a happy medium; faster).

Other chapters discuss broadcasting, multicasting, out of band data, routing sockets, and raw sockets; all topics I hope to learn some day. Again, this is a great book. The 3rd edition brings it up to date for IPV6 and numerous small improvements.

For those of us who have the first two editions of this book, the third edition has the following changes in effect:
· IPv6 updates. In the second version of the book, IPv6 was merely a draft and the sections covering IPv6 has been updated to take these changes into effect.

· POSIX updates. The functions/APIs and examples have been updated to reflect the changes to the latest version of the POSIX specification (1003.1-2001)
· SCTP coverage. 3 new chapters that cover this new reliable, message-based transport protocol have been added.
· Key Management Sockets coverage. Network security and its applicability and use with IPsec.
· Updated Operating Systems and machines that are used to run the examples in the book.
· Some topics such as Transaction TCP and X/Open Transport Interface have been dropped.

Many topics and sections have been updated with the authors' comments. These comments even though simple for someone new to the profession, are extremely useful as they are like hints and tips from one developer to the next to help you out in your next programming assignment.

If this is the only edition of the book that you are reading, you are in for a treat. Topics in Network Programming are covered in detail and using concrete programming examples that all of us can relate to - all Unix, but what else is there?! All kidding aside, the topics are covered well enough that they are useful information under any Operating System. The concepts don't change; sockets are sockets under any Operating System. The function call is different, but one needs to go thru the same steps under any environment.

Being the most popular networking protocol, TCP/IP is covered in Part I of the book. One needs to have prior understanding of the TCP/IP protocol and the OSI model, however. If this is the first time you are looking at the programming aspects of networking protocols, Part I of this book will cover the basics. It starts you off with a couple of simple examples such as daytime client and a daytime server and it builds on that as the reader reads along. TCP, UDP and SCTP (Stream Control Transmission Protocol) are covered in brief in Part I, and basic concepts such as the three-way handshake of TCP and the four-way handshake of SCTP are depicted.

Part II of the book covers sockets and socket programming. Topics such as the socket Address Structure in IPv4 and IPv6 for TCP, UDP and SCTP are covered and examples (the same daytime client/server) are given to convey the point to the reader. It is important to mention here that all the topics and concepts are depicted for the three transport protocols: TCP, UDP and SCTP. Every single socket API under the Unix programming environment is covered and examples are given for each function call to show the reader how the function can be utilized. An entire chapter has been dedicated to Socket Options and how they are used/can be used for best results. Hints are given throughout the chapter to tell the user about the pitfalls and best practices of each option.

After the basics have been covered, various I/O models are depicted in detail and examples are shown to convey the pro's and con's of each I/O model. The five I/O models used thru the book and available under the Unix environment are:
· Blocking I/O
· Non-blocking I/O
· I/O Multiplexing (using select and poll)
· Signal driven I/O
· Asynchronous I/O

SCTP - Stream Control Transmission Protocol, a new IEFT standard are covered in later chapters of 9 and 10 and again in chapter 23. The two interface models of SCTP (one-to-one and one-to-many) are covered in detail, and their differences with TCP are also explained in full. The client/server example that has been used throughout the book is ported to use the new SCTP protocol. The authors then go into great detail explaining the problems that SCTP solves over TCP and where and how it would be useful to use SCTP.

Advanced topics such as IPv4 and IPv6 portability, Unix Domain Protocols, Multicasting and advanced Socket programming for UDP, TCP and SCTP cover the rest of the chapters in this book.
Various options for interoperability between IPv4 and IPv6 start off the last section of the book. A chapter on Advanced I/O functions brings the reader a new perspective of how complicated Network Programming can become. Non-blocking I/O, befits and examples are covered in chapter 16. The topics on Multicasting, and adding reliability to UDP are probably my favorite chapters in this book. The Time Server that has been used throughout the book is re-coded to become a multicast application. Some issues that arise when designing multicast applications such as multicast on a WAN are also discussed.
The third edition of the UNP book is as good as ever. The updates truly reflect solutions to today's challenges in Network Programming. Bill Fenner and Andrew Rudoff did an amazing job continuing the work a true legend in the field of Computer Science.