/ 
XML-Compile-0.70
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/ XML::Compile

NAME

XML::Compile - Compilation based XML processing

INHERITANCE

XML::Compile is extended by
  XML::Compile::Schema
  XML::Compile::WSDL11

SYNOPSIS

# See XML::Compile::Schema / ::WSDL / ::SOAP

DESCRIPTION

Many (professional) applications process XML based on a formal specification expressed as XML Schema. XML::Compile processes XML with the help of such schemas. The Perl program only handles a tree of nested HASHes and ARRAYs, and does not need to understand namespaces and schema nastiness.

Three serious WARNINGS:

.

The focus is on data-centric XML, which means that mixed elements are not understood automatically. However, with using hooks you can work around this.

.

The schema is not strictly validated. In many cases, compile-time errors will get reported. On the other hand, the processed data is strictly validated against the schema: both input and output will follow the specs closely (unless disabled).

.

Imports and includes as specified in schemas are NOT performed automaticly, and schema's and such are NOT collected from internet dynamically; you have to call XML::Compile::Schema::importDefinitions() explictly with locally stored filenames. Includes only work if they have a targetNamespace defined, which is the same as that of the schema it is included into.

For end-users, the following packages are of interest (the other are support packages):

XML::Compile::Schema

Interpret schema elements and types: process XML messages.

XML::Compile::SOAP

Use the SOAP protocol, client side.

XML::Compile::WSDL11

Use SOAP with a WSDL version 1.1 communication specification file.

XML::Compile::SOAP::Daemon

Create a SOAP daemon, directly from a WSDL file. Implementation in progress.

XML::Compile::Dumper

Enables you to save pre-compiled XML handlers, the results of any compileClient. However, this results in huge files, so may not be worth the effort.

METHODS

Methods found in this manual page are shared by the end-user modules, and should not be used directly: objects of type XML::Compile do not exist.

Constructors

These constructors are base class methods to be extended, and therefore should not be accessed directly.

XML::Compile->new(TOP, OPTIONS)

    The TOP is the source of XML. See dataToXML() for valid options.

    If you have compiled/collected all readers and writers you need, you may simply terminate the compiler object: that will clean-up (most of) the XML::LibXML objects.

    Option     --Default
schema_dirs  undef

    . schema_dirs => DIRECTORY|ARRAY-OF-DIRECTORIES

      Where to find schema's. This can be specified with the environment variable SCHEMA_DIRECTORIES or with this option. See addSchemaDirs() for a detailed explanation.

Accessors

$obj->addSchemaDirs(DIRECTORIES|PACKAGE)

XML::Compile->addSchemaDirs(DIRECTORIES|PACKAGE)

    Each time this method is called, the specified DIRECTORIES will be added in front of the list of already known schema directories. Initially, the value of the environment variable SCHEMA_DIRECTORIES is added (therefore tried as last resort). The constructor option schema_dirs is processed first.

    Values which are undef are skipped. ARRAYs are flattened. Arguments are split at colons (on UNIX) or semi-colons (windows) after flattening. The list of directories is returned, in all but VOID context.

    When a .pm PACKAGE filename is provided, then the directory to be used is calculated from it (platform independent). So, something/XML/Compile.pm becomes something/XML/Compile/xsd/. This way, modules can simply add their definitions via XML::Compile->addSchemaDirs(__FILE__) in a BEGIN block or in main. ExtUtils::MakeMaker will install everything what is found in the lib/ tree, so also xsd files. Probably, you also want to use knownNamespace().

    example: adding xsd's from your own distribution

    # file ..../My/Package.pm
package My::Package;

use XML::Compile;
XML::Compile->addSchemaDirs(__FILE__);
# now ...../My/Package/xsd/ is also in the schema search path

use constant MYNS => 'http://my-namespace-uri';
XML::Compile->knownNamespace
 ( &MYNS => 'relative-filename-in-schemadir'
 );

$obj->findSchemaFile(FILENAME)

    Runs through all defined schema directories (see addSchemaDirs()) in search of the specified FILENAME. When the FILENAME is absolute, that will be used, and no search is needed. An undef is returned when the file is not found, otherwise a full path to the file is returned to the caller.

    Although the file may be found, it still could be unreadible.

$obj->knownNamespace(NAMESPACE|PAIRS)

XML::Compile->knownNamespace(NAMESPACE|PAIRS)

    If used with only one NAMESPACE, it returns the filename in the distribution (not the full path) which contains the definition.

    When PAIRS of NAMESPACE-FILENAME are given, then those get defined. This is typically called during the initiation of modules, like XML::Compile::WSDL and XML::Compile::SOAP. The definitions are global: not related to specific instances.

    The FILENAMES are relative to the directories as specified with some addSchemaDirs() call.

Read XML

$obj->dataToXML(NODE|REF-XML-STRING|XML-STRING|FILENAME|FILEHANDLE|KNOWN)

    Collect XML data, from a wide variety of sources. In SCALAR context, a XML::LibXML::Element or ::Document is returned. In LIST context, pairs of additional information follow the result.

    When a ready XML::LibXML NODE is provided, it is returned immediately and unchanged. A SCALAR reference is interpreted as reference to XML as plain text (XML texts can be large, and you can improve performance by passing it around by reference instead of copy). Any value which starts with blanks followed by a '<' is interpreted as XML text.

    You may also specify a pre-defined known name-space URI. A set of definition files is included in the distribution, and installed somewhere when this all gets installed. Either define an environment variable named SCHEMA_LOCATION or use new(schema_dirs) (option available to all end-user objects) to inform the library where to find these files.

    According the XML::LibXML::Parser manual page, passing a FILEHANDLE is much slower than pasing a FILENAME. However, it may be needed to open a file with an explicit character-set.

    example:

    my $xml = $schema->dataToXML('/etc/config.xml');
my ($xml, %details) = $schema->dataToXML($something);

Filters

$obj->walkTree(NODE, CODE)

    Walks the whole tree from NODE downwards, calling the CODE reference for each NODE found. When that routine returns false, the child nodes will be skipped.

DETAILS

Comparison

Where other Perl modules, like SOAP::WSDL help you using these schemas (often with a lot of run-time [XPath] searches), XML::Compile takes a different approach: instead of run-time processing of the specification, it will first compile the expected structure into a pure Perl CODE reference, and then use that to process the data as often as needed.

There are many Perl modules with the same intention as this one: translate between XML and nested hashes. However, there are a few serious differences: because the schema is used here (and not by the other modules), we can validate the data. XML requires validation but quite a number of modules simply ignore that.

Next to this, data-types are formatted and processed correctly; for instance, the specification prescribes that the Integer data-type must accept values of at least 18 digits... not just Perl's idea of longs.

XML::Compile supports the more complex data-types like list, union, substitutionGroup (unions on complex type level), and even the nasty any and anyAttribute, which is rarely the case for the other modules.

DIAGNOSTICS

Error: cannot find pre-installed name-space files

    Use $ENV{SCHEMA_LOCATION} or new(schema_dirs) to express location of installed name-space files, which came with the XML::Compile distribution package.

Error: don't known how to interpret XML data

Error: no XML data specified

SEE ALSO

This module is part of XML-Compile distribution version 0.70, built on March 14, 2008. Website: http://perl.overmeer.net/xml-compile/

LICENSE

Copyrights 2006-2008 by Mark Overmeer. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See http://www.perl.com/perl/misc/Artistic.html