Book Image

Tcl 8.5 Network Programming

Book Image

Tcl 8.5 Network Programming

Overview of this book

Tcl (Tool Command Language) is a very powerful and easy to learn dynamic programming language, suitable for a very wide range of uses. Tcl is regarded as one of the best-kept secrets in the software industry. This book gives you a hands-on experience on Tcl, helping you develop network-aware applications using this mature yet evolving language. This book shows you how to create network-aware applications with Tcl language. Packed with practical examples, the book not only takes you through the implementation of network protocols in Tcl, but also key aspects of Tcl programming. The book starts with the basic element of Tcl programming as we take a look at the syntax and fundamental commands of the language. To get us ready for network programming, we look at important Tcl features such as object-oriented programming, accessing files, packaging in TCL, event driven programming, and multithreaded applications. To create standalone single-file executable applications with Tcl we take a look at the Starpack technology, and ensure that we’ll be able to create robust applications with a thorough coverage of troubleshooting and debugging Tcl applications. The book is really about network programming, and it will not let you down with its deep coverage of these topics. Of course we look at protocols, but there are plenty of practical examples to keep things moving along. We start with the TCP and UDP protocols, and look at some other protocols to see examples of synchronizing time with other servers, querying user information and authenticating users over LDAP and performing DNS queries. The book explains Simple Network Management Protocol (SNMP), which is often used for monitoring and gathering information from various devices, such as routers, gateways, printers and many other types of equipment. We’ll also look at web programming in Tcl; processing the requests coming from the clients via the HTTP protocol and responding to these requests. You’ll be able to create a complete solution for creating a client-server application in Tcl. To round things off, you’ll see how to secure your networked applications, build public key infrastructure into your application and use Tcl’s safe interpreter feature to reduce risk of running code from unknown source.
Table of Contents (18 chapters)
Tcl 8.5 Network Programming
Credits
About the Authors
About the Reviewers
Preface
4
Troubleshooting Tcl applications

Introduction to TclHttpd


The possibilities offered by Tcl go far beyond plain CGI scripting—the entire web server can be written using this language. But before you eagerly start writing your own, know that this task was already done by Brent Welch, the author of TclHttpd—the powerful web server completely implemented using the Tcl language. The author claims that at the beginning the entire code had about 175 lines. Tcl's input/output subsystem is well crafted, and it offers maximum usability with minimum coding.

The homepage of TclHttpd is located at http://www.tcl.tk/software/tclhttpd/. The latest available officially released version 3.5.1 was released on May 27th, 2004.This is both bad and good information: the code is pretty old and not actively supported, but it reached the maturity level long time ago. The code has its years, but you can't question its usability.

Note

The source code of the examples presented in this section is located in the in the 04tclhttpd directory in the source...