Résumé
Perl soared to popularity as a language for creating and managing web content, but with LWP (Library for WWW in Perl), Perl is equally adept at consuming information on the Web. LWP is a suite of modules for fetching and processing web pages.
The Web is a vast data source that contains everything from stock prices to movie credits, and with LWP all that data is just a few lines of code away. Anything you do on the Web, whether it's buying or selling, reading or writing, uploading or downloading, news to e-commerce, can be controlled with Perl and LWP. You can automate Web-based purchase orders as easily as you can set up a program to download MP3 files from a web site.
Perl & LWP covers:- Understanding LWP and its design
- Fetching and analyzing URLs
- Extracting information from HTML using regular expressions and tokens
- Working with the structure of HTML documents using trees
- Setting and inspecting HTTP headers and response codes
- Managing cookies
- Accessing information that requires authentication
- Extracting links
- Cooperating with proxy caches
- Writing web spiders (also known as robots) in a safe fashion
Perl & LWP includes many step-by-step examples that show how to apply the various techniques. Programs to extract information from the web sites of BBC News, Altavista, ABEBooks.com, and the Weather Underground, to name just a few, are explained in detail, so that you understand how and why they work.
Perl programmers who want to automate and mine the web can pick up this book and be immediately productive. Written by a contributor to LWP, and with a foreword by one of LWP's creators, Perl & LWP is the authoritative guide to this powerful and popular toolkit.
Contents
Foreword
Preface
1. Introduction to Web Automation
The Web as Data Source
History of LWP
Installing LWP
Words of Caution
LWP in Action
2. Web Basics
URLs
An HTTP Transaction
LWP::Simple
Fetching Documents Without
LWP::Simple
Example: AltaVista
HTTP POST
Example: Babelfish
3. The LWP Class Model
The Basic Classes
Programming with LWP Classes
Inside the do_GET and do_POST
Functions
User Agents
HTTP::Response Objects
LWP Classes: Behind the Scenes
4. URLs
Parsing URLs
Relative URLs
Converting Absolute URLs to
Relative
Converting Relative URLs to
Absolute
5. Forms
Elements of an HTML Form
LWP and GET Requests
Automating Form Analysis
Idiosyncrasies of HTML Forms
POST Example: License Plates
POST Example: ABEBooks.com
File Uploads
Limits on Forms
6. Simple HTML Processing with Regular
Expressions
Automating Data Extraction
Regular Expression Techniques
Troubleshooting
When Regular Expressions Aren't
Enough
Example: Extracting Links from a
Bookmark File
Example: Extracting Links from
Arbitrary HTML
Example: Extracting Temperatures from
Weather Underground
7. HTML Processing with Tokens
HTML as Tokens
Basic HTML::TokeParser Use
Individual Tokens
Token Sequences
More HTML::TokeParser Methods
Using Extracted Text
8. Tokenizing Walkthrough
The Problem
Getting the Data
Inspecting the HTML
First Code
Narrowing In
Rewrite for Features
Alternatives
9. HTML Processing with Trees
Introduction to Trees
HTML::TreeBuilder
Processing
Example: BBC News
Example: Fresh Air
10. Modifying HTML with Trees
Changing Attributes
Deleting Images
Detaching and Reattaching
Attaching in Another Tree
Creating New Elements
11. Cookies, Authentication, and Advanced
Requests
Cookies
Adding Extra Request Header
Lines
Authentication
An HTTP Authentication Example: The
Unicode Mailing Archive
12. Spiders
Types of Web-Querying Programs
A User Agent for Robots
Example: A Link-Checking Spider
Ideas for Further Expansion
A. LWP Modules
B. HTTP Status Codes
C. Common MIME Types
D. Language Tags
E. Common Content Encodings
F. ASCII Table
G. User's View of Object-Oriented Modules
Index
L'auteur - Sean M. Burke
Sean M. Burke is an active member in the Perl community and one of CPAN's most prolific module authors. He has been a columnist for The Perl Journal since 1998, and is an authority on markup languages. Trained as a linguist, he also develops tools for software internationalization and native language preservation. Sean is also the author of O'Reilly's Perl & LWP.
Caractéristiques techniques
| PAPIER | |
| Éditeur(s) | O'Reilly |
| Auteur(s) | Sean M. Burke |
| Parution | 12/07/2002 |
| Nb. de pages | 242 |
| Format | 18 x 23,5 |
| Couverture | Broché |
| Poids | 416g |
| Intérieur | Noir et Blanc |
| EAN13 | 9780596001780 |
| ISBN13 | 978-0-596-00178-0 |
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