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Perl & Lwp Paperback – Jun 20 2002
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Perl and LWP explains how to write programs that browse the Web, using the excellent Library for the World Wide Web or LWP. It is aimed at developers who already know both Perl and HTML, although you don't need to be an expert in either.
The fascination of this topic is that it makes you see the Web in a different way, not as a set of pages for users to browse, but as a huge database for your programs to explore. The most robust technique for querying Web sites programmatically is through XML Web Services, but this approach is in its infancy. LWP takes a different route, called screen-scraping. In essence, your Perl code pretends to be a browser and grabs HTML for processing. Using LWP you could write a command-line program to search your favourite auction site, fetch news headlines, or check multiple retail sites for the best prices. As the author acknowledges, the problem with screen-scraping is its brittleness: if the target Web site adopts a new look, it breaks your code. There are also interesting fair usage issues. Even so, it's a powerful technique with many possible applications. This clear and concise guide comes complete with typically terse Perl code examples. Topics include LWP basics, posting form data, processing results with regular expressions, using trees to process HTML, imitating different browser types, and supporting cookies programmatically. An appendix offers handy information like HTTP status codes, character tables, and MIME types. LWP is large, but while this title does not attempt to cover all the modules, it does provide all you need to start coding your own Web-mining programs.--Tim Anderson
From the Publisher
The LWP (Library for WWW in Perl) suite of modules lets your programs download and extract information from the Web. Perl & LWP shows how to make web requests, submit forms, and even provide authentication information, and it demonstrates using regular expressions, tokens, and trees to parse HTML.. This book is a must have for Perl programmers who want to automate and mine the Web.See all Product Description
Top Customer Reviews
It's a good guide for someone who plans to extract information from the source code of web pages. A little knowledge of Perl would help to understand the vast collection of code segments, which can become the skeleton of your own code. The book also discusses web resource ethics and how to code responsibly.
I recommend this book.
More experienced programmers will understand better why things work, but any Perl programmer will set this book down feeling empowered to turn the web into their own valet. No longer do you need to check multiple sites looking for interesting information. Instead, you can readily author code to do that for you and alert you when items of interest are found. You can use these tools to free up personal time, to harvest information to inform business decisions, to automate tedious web application testing, and a zillion other things.
The author's clear exploration of the relevant Perl modules leaves the reader with a good depth of understanding of what these modules do, when you might want to use which module, and how to use them for real world tasks. Before reading the book, I knew of these modules, but they were a rather intimidating pile. I'd used a few of them on occasion for rather limited projects, but was reluctant to invest the time required to read all of the documentation from the whole collection. Mountains of method-level documentation do not a tutorial make. This book takes all of that information, selects the most important parts, and ensures that those parts are covered in progressively more powerful and/or flexible examples.Read more ›
If the above hasn't totally disqualified me from commenting, I just wanted to note some things most reviewers have ignored.
The book is an excellent resource for two kinds of people.
Many people scan technical books looking for little scripts and thingies; a few lines changed and BOOM! They have the program they always wanted. Sean provides those in abundance.
It is also a good resource for a complete novice to learn about the hodgepodge of technologies we call the web - the ... wire protocol, markup languages, tree-based parsers, and encodings, to name just a few. The author is an expert in all of these, but has restrained himself to provide just enough information to get a programmer going. I was impressed time and again with how he manages to give the reader exactly enough knowledge to get their tasks done, with short but accurate explanations and pointers on where to learn more.
Best of all, this is a funny technical book. Usually if a technical book has pretensions to humor, it jabs you in the arm repeatedly with lots of groaner puns and dumb cartoons, in order to fill the space between bland code sections. But Sean has sprinkled the *code sections* with his dada sense of humor, which also highlights the difference between mere placeholder data and the concept being illustrated. And then the text gets right back to the point.
This is a slim work (242 pages, no thicker than my thumb) but packs a lot of value for your money. So buy it already.
My only criticism is that it is exclusively focused on consuming services on the web - like downloading TV listings and so on.Read more ›
Most recent customer reviews
If you are unfamiliar with LWP and web scraping, or HTML parsing using tokens and trees, I strongly recommend this book. Read morePublished on March 15 2003 by Matthew D. Huwiler
This book is a comprehensive and authoritative guide to web automation. It reads as both a gentle tutorial and a well organized reference. Read morePublished on Aug. 30 2002 by K. Boggs
As a web programmer, I had dealt with several such projects dealing with web automation and writing simple crawlers even before I read "Perl & LWP". Read morePublished on Aug. 7 2002
I was definitely interested when I first heard that O'Reilly were publishing a book on LWP. LWP is a definitive collection of perl modules covering everything you could think of... Read morePublished on July 16 2002 by Gavin
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