XMLin() and XMLout() Methods
This section describes two key methods in the XML::Simple module, XMLin() and XMLout(), to convert XML text string into a hash structure representing the XML structure and to convert the hash back to a string.
XML::Simple module is an easy API to read and write XML files. It offers two main methods:
XMLin() and XMLout().
XMLin(str) - Method to parse the XML input into a hash, and return the reference of the hash.
The XML input can be specified in 3 ways:
- If the method is called with no parameter, the XML input is in script_name.xml, where
script_name is the same name of the calling Perl script file.
- If the method is called with a string parameter containing <tag>, the XML input is the string parameter.
- If the method is called with a string parameter without any <tag>, the XML input is in
the file with the string parameter as file name.
XMLout(ref) - Method to write the hash pointed by the specified reference into an XML string,
and return XML string.
If XML::Simple is installed as part of the ActivePerl package. No extra download and installation steps needed.
Here is a simple program to show you how to use XML:Simple:
#- Copyright (c) 1999 by Dr. Herong Yang, http://www.herongyang.com/
my $xs = new XML::Simple();
my $ref = $xs->XMLin("<p>Hello world!</p>");
my $xml = $xs->XMLout($ref);
It's interesting to see from the output that the <p> tag has been changed
to <opt> during the read and write operations. This is because of the default
setting of the option: keeproot. I will explain some of the important options later
in this chapter.
Table of Contents
About This Book
Perl on Linux Systems
ActivePerl on Windows Systems
Data Types: Values and Variables
Expressions, Operations and Simple Statements
User Defined Subroutines
Perl Built-in Debugger
Name Spaces and Perl Module Files
Symbolic (or Soft) References
Hard References - Addresses of Memory Objects
Objects (or References) and Classes (or Packages)
Typeglob and Importing Identifiers from Other Packages
String Built-in Functions and Performance
File Handles and Data Input/Output
Open Files in Binary Mode
Open Directories and Read File Names
File System Functions and Operations
Converting Perl Script to Executable Binary
Using DBM Database Files
Using MySQL Database Server
Socket Communication Over the Internet
►XML::Simple Module - XML Parser and Generator
►XMLin() and XMLout() Methods
XML Parsing Options
"forcearray" - Forcing Element Contents as Arrays
"suppressempty" - Parsing Empty Elements
"keyattr" - Namings Attributes as Keys
XmlSimpleHash.pl - XML Hash Example
XML Communication Model
SOAP::Lite - SOAP Server-Client Communication Module
Perl Programs as IIS Server CGI Scripts
CGI (Common Gateway Interface)
XML-RPC - Remote Procedure Call with XML and HTTP
RPC::XML - Perl Implementation of XML-RPC
Integrating Perl with Apache Web Server
CGI.pm Module for Building Web Pages
LWP::UserAgent and Web Site Testing
PDF Printing Version