On the World Wide Web, people are accustomed to using graphical browsers such as Netscape Navigator or Mosaic as their only interface for visiting remote sites, accessing up-to-date documents, and filling out forms. But graphical browsers can be limiting: the very interactivity that makes them so intuitive to use also makes them clumsy for automating tasks. If you want to get the latest weather report every few hours, track a Federal Express package online, or use a dictionary server repeatedly throughout the day, using your browser to perform the same task over and over can become cumbersome. As with any repetitive task, these applications are best done by writing a script.Web Client Programming with Perl shows you how to extend scripting skills to the Web. This book teaches you the basics of how browsers communicate with servers and how to write your own customized Web clients to automate common tasks. It is intended for those who are motivated to develop software that offers a more flexible and dynamic response than a standard Web browser.Using this book, you'll learn how to:
Automate repetitive queries on the Web
Detect broken hyperlinks on your site
Write simple "robots" that traverse hyperlinks across a site, and across the Web in general
This book will be of interest to:
Web administrators who need to automate repetitive tasks or reduce maintenance time
UNIX shell programmers who want to interface their scripts to the Web
Commercial software developers and consultants who need reference material for technical Web specifications and proof-of-concept examples
Most of the examples in this book use Perl, a versatile and portable language that is already familiar to many CGI programmers and UNIX power users. The book does not teach Perl, but the techniques used in the book should be easily followed by anyone with some programming background and can be adapted to whatever language you choose.
Our look is the result of reader comments, our own experimentation, and feedback from distribution channels. Distinctive covers complement our distinctive approach to technical topics, breathing personality and life into potentially dry subjects. The bird featured on the cover of Web Client Programming with Perl is a white pelican. White pelicans are among the world's largest birds. To creatures not belonging to the order pelicanus erythrorynchos (from the Greek pelicus, meaning "ax" -- probably from the shape of its bill -- and erythros, "beak"), the white pelican's profile probably appears preposterous with an enormous pouched bill with a hook on the end, large-proportioned body, and stubby legs with webbed feet. But those who have witnessed pelicans circling in flight at dizzying heights or gliding through water in pursuit of a catfish can attest to their grace in motion.The adult white pelican is 4-6 feet long with a giant wingspread of 8-9 1/2 feet. Usual weight is 10-17 pounds but can reach 30 pounds. The tips of the wings are black. The large pouched bill is orange or salmon-colored. Eyes are orange-yellow; the legs and feet are orange-red. Feet are totipalmate, which means that all four toes, including the back one, are united by a Web of skin. Unlike many birds, the male and female have the same coloring and plumage.Contrary to popular belief, pelicans do not store fish in their bills. They thrust their heads under water, using the pouch as a dip net for catching fish. The pouch can hold 17 pints of water. Fish are actually stored in the esophagus when the pelican travels.The white pelican flies with head drawn back and bill resting on the breast. The birds fly at heights up to 8,000 feet. By using thermal currents they can circle for hours.White pelicans nest on isolated islands in lakes of inland Canada and the U.S. They winter in coastal California and along the Pacific coast to Guatemala. The largest nesting colony in North America is at Chase Lake National Wildlife Refuge in North Dakota.Pelicans can live to a great age. The accepted official record is 52 years, though the Emperor Maximilian of Mexico is said to have had a pelican who always accompanied his troops when on the march; that pelican is said to have lived for 80 years. Edie Freedman designed the cover of this book, using a 19th-century engraving from the Dover Pictorial Archive. The cover layout was produced with Quark XPress 3.3 using the ITC Garamond font.The inside layout was designed by Nancy Priest and implemented in FrameMaker by Mike Sierra. The text and heading fonts are ITC Garamond Light and Gara mond Book. The illustrations that appear in the book were created in Macromedia Freehand 5.0 by Chris Reilley. This colophon was written by Kismet McDonough-Chan.