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

Debugging


While logging techniques save information about execution flow to allow you to analyze it later, debugging offers a different concept. It allows you to interact with a live, running application, review and modify its internal state, and halt execution at points of your choice using breakpoints.

The best graphical debugging tools, Inspector and Debugger, are offered by ActiveState as a part of the Tcl Dev Kit bundle, available at http://www.activestate.com/tcl_dev_kit/. There is a 21-day free trial period, so you do not need to buy it blindly. In this chapter, we will describe the tools offered by version 5.1.0. We will also describe its ancestor, the free TclPro Debugger (version 1.4), available at http://www.tcl.tk/software/tclpro/. Although it is based on old Tcl 8.3, it is still a free alternative worth considering.

Tcl Dev Kit Inspector

Before we focus on debuggers, we will first discuss the Tcl Dev Kit Inspector, which is not really a thorough-bred debugging application. It...