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XML Matters: Comparing W3C XML Schemas and Document Type Definitions (DTDs)
This installment of the XML Matters column steps up to the challenge of comparing schemas and DTDs and clarifying just what is going on in the XML schema world.
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01 Mar 2001 |
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XML Matters: XML for word processors
Recent versions of the three major free software word processing programs have all adopted XML as their native document format. The approaches to XML taken by AbiWord, KOffice's KWord, and OpenOffice.org Writer differ somewhat between the applications -- largely reflecting the underlying development focus of each project. Here, David takes a look at how these projects and all open source word processor developers have realized the advantages of XML as a document format: componentization of parsers and writers; openness and formality of format specification; and applicability of XSLT and other transformation APIs.
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25 Feb 2004 |
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XML Matters: The XOM Java XML API
In this installment, David looks at Elliotte Rusty Harold's XOM. Broadly speaking, this is yet another object-oriented XML API, somewhat in the style of DOM, however a number of features set XOM apart, and Harold argues that they are important design elements. Chief among these is a rigorous insistence on maintaining invariants in in-memory objects so that an XOM instance can always be serialized to correct XML. In addition, XOM aims at greater simplicity and regularity than other Java XML APIs.
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17 Dec 2003 |
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XML Matters: Investigating SXML and SSAX
In previous installments, David has looked at XML libraries for various programming languages, and their various strengths and weaknesses. This time, he looks at the Lisp/Scheme family of languages that continues to endure in popularity, especially in teaching and among purists. Included in the discussion are the SSAX library for Scheme (an efficient pure-functional parser), the SXML tree library (similar to DOM), and the related tools SXSLT and SXPath, which have been created to work with them. David covers the advantages of parsing in a strongly functional language, and compares SSAX with libraries for other languages.
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23 Oct 2003 |
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XML Matters: TEI -- the Text Encoding Initiative
Nowadays, XML is usually thought of as a markup technique utilized by programmers to encode computer-oriented data. Even DocBook and similar document-oriented DTDs focus on preparation of technical documentation. However, the real roots of XML are in the SGML community, which is largely composed of publishers, archivists, librarians, and scholars. In this installment, David looks at Text Encoding Initiative, an XML schema devoted to the markup of literary and linguistic texts. TEI allows useful abstractions of typographic features of source documents, but in a manner that enables effective searching, indexing, comparison, and print publication -- something not possible with publications archived as mere photographic images.
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04 Sep 2003 |
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XML Matters: The RXP parser
RXP is a validating parser written in C that creates a non-DOM tree representation of XML documents. While RXP itself is not well documented -- and not for the faint of heart -- at least two excellent higher level APIs have been built on top of RXP: pyRXP, a Python binding; and LT XML, a collection of utilities and libraries. In this article, David introduces you to RXP, compares it with the expat parser, and briefly discusses pyRXP and LT XML as ways of taking advantage of the speed RXP has to offer without all of its complexity.
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04 Aug 2003 |
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XML Matters: More on XML and compression
In an earlier installment of this column, David examined techniques by which XML documents can be reversibly restructured to improve compression. For large XML documents and embedded processes, however, restructuring an entire source prior to a compression pass might be impractical. In this installment, David examines how well restructuring techniques can be adapted to block-level processing -- in terms of both compression improvements and CPU/memory requirements.
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01 Apr 2002 |
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XML Matters: The REXML library
David introduces Ruby Electric XML (REXML), a library that takes the strengths of Ruby, and builds XML processing around them.
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01 Mar 2002 |
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XML Matters: Intro to PYX
XML is a fairly simple format. It uses plain Unicode text rather than binary encoding, and all the structures are declared with predictable-looking tags. Nonetheless, there are still enough rules in the XML grammar that a carefully debugged parser is needed to process XML documents -- and every parser imposes its own particular programming style. An alternative is to make XML even simpler. The open-source PYX format is a purely line-oriented format for representing XML documents that allows for much easier processing of XML document contents with common text tools like grep,sed, awk, wc, and the usual UNIX collection.
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01 Feb 2002 |
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XML Matters: More on XML in Python: 4Suite
Think of the 4Suite set of Python modules as a "connoisseur's choice" of XML tools. With their range and sophistication, 4Suite tools give a programmer both a lot of power and a steep learning curve. But for moving beyond the base XML capabilities offered by recent versions of Python, 4Suite offers useful options. Here, David takes a look at the most noteworthy aspects of 4Suite, and shows you how it can add useful capabilities to your Python/XML tool set.
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01 Jan 2002 |
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XML Matters: XML-RPC as object model
Columnist David Mertz examines XML-RPC as a way of modeling object data, and -- in response to reader feedback -- compares XML-RPC as a means of serializing objects with the xml_pickle module discussed in his earlier columns.
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01 Dec 2001 |
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XML Matters: XML and compression
This XML Matters column explores several approaches to compressing XML documents.
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01 Sep 2001 |
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XML Matters: Transcending the limits of DOM, SAX, and XSLT
Consider Haskell in lieu of DOM, SAX, or XSLT for processing XML data. The library HaXml creates representations of XML documents as native recursive data structures in the functional language Haskell. HaXml brings with it a set of powerful higher order functions for operating on these "datafied" XML documents. Many of the HaXml techniques are far more elegant, compact, and powerful than the ones found in familiar techniques like DOM, SAX, or XSLT. Code samples demonstrate the techniques.
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01 Oct 2001 |
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XML Matters: Using Python modules xml2sql and dtd2sql
David Mertz shows that the reverse direction of translating an XML document and DTD back into an RDBMS storage format is equally possible, but with its own set of constraints and complications.
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01 Jun 2001 |
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XML Matters: Revisiting xml_pickle and xml_objectify
This column presents some of the changes to his module suite, as well as some tips on advanced aspects of using and customizing the modules.
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01 Jun 2001 |
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XML Matters: DTDs and XML documents from SQL queries
This column discusses the public-domain sql2dtd and sql2xml utilities that allow RDBMS-independent generation of portable XML result sets.
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01 May 2001 |
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XML Matters: Indexing XML documents
As XML document storage formats become popular, especially for prose-oriented documents, the task of locating contents within XML document collections becomes more difficult. This column extends the generic full text indexer presented in David's Charming Python #15 column to include XML-specific search and indexing features. This column discusses how the tool design addresses indexing to take advantage of the hierarchical node structure of XML.
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01 May 2001 |
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XML Matters: Putting XML in context with hierarchical, relational, and object-oriented models
On the way to making a point about how XML is best suited to work with databases, David Mertz discusses how XML fits with hierarchical, relational, and object-oriented data modeling paradigms.
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01 Apr 2001 |
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XML Matters: Program with SVG
Scalable Vector Graphics (SVG) is an XML format that describes scale-independent graphics, with good support in free software and commercial tools. In this installment, David introduces scripting and animation with SVG, and touches on manipulating SVG through DOM. Because SVG is XML, it lends itself to transformation and/or generation with any of the tools and libraries you might use for XML generally.
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15 Apr 2005 |
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XML Matters: Describe XML content with the Dublin Core Metadata Initiative
The Dublin Core Metadata Initiative (DCMI) is a standardized vocabulary for handling information about documents. The DCMI vocabulary defines a hierarchy of terms that describe the purpose, context, and origin of a document (rather than the document itself). David shows you how DCMI provides a set of metadata primitives that you can reuse (through namespaces) in broader XML vocabularies, such as RSS variants. Various standards, including those from ISO and NISO, have adopted parts of DCMI.
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06 Aug 2004 |
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XML Matters: The Web ain't just for 2D any more
Once upon a time, 3D for the Web promised to be as easy as building a Web page. Unfortunately, 3D -- even simple 3D -- is more complex than displaying scrolling text and pictures. Each VRML vendor implemented a different subset of the spec, and it never gained traction. And so 3D on the Web faded away. Or did it? It turns out that VRML lives on in its XML flavor, X3D, which has grown to encompass VRML's siblings H-Anim (Humanoid Animation) and GeoVRML. Can 3D on the Web finally be used for more than virtual shopping malls? The latest installment of this mini-series on XML media shows that it can. In this article, Dethe focuses on a couple of uses that X3D is ready for now, and takes a look at where it might go in the future.
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15 Dec 2005 |
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XML Matters: SVG and the scriptless script
Scalable Vector Graphics (SVG) browsers are becoming mainstream now, and they can be used in many powerful ways. Continuing on from David's earlier SVG column, Dethe looks at some of the ways that declarative markup can replace script for animation and other common scripting tasks. In the process, he briefly looks at replacing script with declarative markup in other XML dialects. Moving common scripting tasks into declarative markup can eliminate the need for tedious boilerplate code, reduce errors, and make your script's intent easier to follow, freeing you to focus on your code's unique aspects.
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25 Oct 2005 |
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XML Matters: Practical XML data design and manipulation for voting systems
In this installment, David discusses his practical experiences developing interrelated XML data formats for the EVM2003 Free Software project to develop voting machines that produce voter-verifiable paper ballots. Some design principles of format subsetting emerge. In addition, David looks at how an application-specific meaning for XML document equivalence can be programmed, and why canonicalization is insufficient.
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28 Jun 2004 |
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XML Matters: GUIs and XML configuration data, Part 2
David continues his discussion of how XML is used in the configuration of GUI interfaces. He looks at Mozilla's XML-based User Interface Language (XUL) which allows you to write applications that run without any particular dependency on the choice of underlying operating system. This may seem strange at first, but you'll soon see that this Mozilla project offers powerful tools for GUI building that allow you to develop for an extensive base of installed users.
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26 May 2004 |
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XML Matters: GUIs and XML configuration data
Over time, XML has permeated many niches. One area where XML is used increasingly is in the configuration of graphical user interfaces, especially in elements that are persistent but should not be fixed at compile-time. In this installment, David looks at the use of XML in Mac OS X's Aqua GUI, and in the K Desktop Environment (KDE) which is either standard or available in most modern Linux distributions.
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28 Apr 2004 |
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XML Matters: Process XML in Python with ElementTree
Fredrik Lundh's ElementTree module is an increasingly popular API for light-weight and fast manipulation of XML documents within Python. In this installment, David contrasts ElementTree with several other libraries devoted to processing XML instances as object trees, especially with his own gnosis.xml.objectify module.
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24 Jun 2003 |
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XML Matters: Kicking back with RELAX NG, Part 3
The RELAX NG compact syntax provides a much less verbose, and easier to read, format for describing the same semantic constraints as RELAX NG XML syntax. This installment looks at tools for working with and transforming between the two syntax forms.
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14 May 2003 |
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XML Matters: Kicking back with RELAX NG, Part 2
RELAX NG schemas provide a more powerful, concise, and semantically straightforward means of describing classes of valid XML instances than do W3C XML Schemas. In this installment, David continues the discussion of RELAX NG begun in part 1 of this series by addressing a few additional semantic issues and looking at tools for working with RELAX NG.
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26 Mar 2003 |
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XML Matters: Summary
Welcome to XML Matters, a regular column that illustrates general programming concepts and offers programming code to the programming community that you, as an individual developer, can utilize for your own purpose.
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03 Dec 2004 |
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XML Matters: Kicking back with RELAX NG, Part 1
RELAX NG schemas provide a more powerful, more concise, and semantically more straightforward means of describing classes of valid XML instances than do W3C XML Schemas. The virtue of RELAX NG is that it extends the well-proven semantics of DTDs while allowing orthogonally extensible datatypes and easy composition of related instance models. David takes a first look at RELAX NG in this, the first installment of a three-part series.
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01 Feb 2003 |
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XML Matters: reStructuredText
The document format called reStructuredText has been adopted as one of the official source formats for Python documentation, but is also useful for other types of documentation. reStructuredText is an interesting hybrid of technologies -- in syntax and appearance it is similar to other "almost-plaintext" formats, but in semantics and API it is very close to XML. David takes a look at this format and shows you how existing tools can transform reStructuredText into several XML dialects (docutils, DocBook, OpenOffice), along with other useful formats like LaTeX, HTML, and PDF.
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01 Feb 2003 |
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XML Matters: Roundup of XML editors, Part 2
This second part of David's XML editor review looks at Windows-based products -- specifically, Altova's XML Spy, Wattle Software's XMLwriter, NetBryx Technologies' EditML Pro, and Corel's XMetal. In the year and a half since David's last look at this category of tools, they have progressed from largely cosmetic wrappers around text editors to fleshed-out development environments that greatly ease working with XML-oriented technologies.
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01 Sep 2002 |
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XML Matters: Roundup of XML editors, Part 1
In this two-part series on XML editors, David looks at the progress of commercial tools in the year-and-a-half since he last looked at this tools category. These tools have progressed from largely cosmetic wrappers around text editors to fleshed-out development environments that substantially ease the process of working with XML-oriented technologies. This first installment examines Java and MacOS applications, specifically Morphon Technologies' Morphon 2.0.5, SyncRO's <oXygen/> 1.2.1, and ElfData's XML Editor 1.14.
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21 Aug 2006 |
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XML Matters: Enforcing validity with the gnosis.xml.validity library
This installment discusses the author's gnosis.xml.validity library for enforcing validity in Python objects that are intended for XML serialization.
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01 Jul 2002 |
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XML Matters: A roundup of editors
In this column David Mertz gives an up-to-date review of a half-dozen leading XML editors. He compares the strengths, weaknesses and capabilities of each -- especially for handling text-heavy prose documents. The column addresses the very practical question of just how one goes about creating, modifying, and maintaining prose-oriented XML documents.
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01 Jan 2001 |
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XML Matters: Transforming DocBook documents using XSLT
Using a DocBook example, David Mertz shows how to convert an XML document to HTML through XSLT (Extensible Stylesheet Language Transformation). Along the way, your intrepid columnist discusses four alternative approaches for transforming XML documents and shares what he experienced in experimenting with some open source tools. Sample code includes fragments of XSLT documents, valid HTML outputter code in XSLT for a simple DocBook chapter, and a brief XSLT looping example.
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01 Nov 2000 |
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XML Matters: Getting comfortable with the DocBook XML dialect
This column continues the discussion of the benefits of using DocBook to convert documents in heterogeneous formats to a single, standard XML format. It also looks at some DocBook tags in greater detail and discusses how to compose a basic DocBook document.
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01 Oct 2000 |
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XML Matters: Getting started with the DocBook XML dialect
In the third installment of his "XML Matters" column, David Mertz gets you started with DocBook, an SGML/XML dialect that describes the content of technical articles and other documents. David discusses the benefits of using DocBook, and then describes how to plan and modularize a large document conversion project.
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01 Oct 2000 |
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XML Matters: On the 'Pythonic' treatment of XML documents as objects
In the first installment of his new 'XML Matters' column -- and as part of his ongoing quest to create a more seamless integration between XML and Python -- David Mertz presents the xml_pickle module. Mertz discusses the design goals and decisions that went into xml_pickle and provides a list of likely uses.
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01 Aug 2000 |
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XML Matters: Beyond the DOM
The Document Object Model (DOM) is one of the most widely implemented tools for manipulating XML and HTML data, but it is rarely used to its full potential. By taking advantage of the DOM and extending it to be even easier to use, you gain a powerful tool for XML applications, including dynamic Web applications.
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20 May 2005 |
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XML Matters: Up and Atom
Atom the format is completed, and Atom the protocol is shaping up. How does Atom interact with microformats? Where will you store all the Atom content? This article presents some prototype Atom stores and explores the possibilities.
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23 May 2006 |
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XML Matters: Pipestreaming microformats
An increasingly common use of XML is to move small snippets of content through an arbitrary processing workflow, much like text through UNIX pipes. The snippets can be from one document or many, whole documents or fragments, or synthesized on demand from other data sources, thus streaming is an appropriate metaphor. The microformat approach of using well-defined snippets of XML or XHTML lends itself well to this approach. You'll look at some examples of this using existing Python and Java(TM) tools and the hCard and hCalendar microformats.
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25 Apr 2006 |
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XML Matters: YAML improves on XML
In this article, David introduces you to YAML, a data serialization format that can be easily read by humans and is well-suited to encoding the data types used in dynamic programming languages. In contrast to XML, YAML uses clean and very minimal structural indicators, relying largely on indentation of nested elements. More importantly, for many tasks the superior syntax of YAML is the far better semantic fit between YAML and "natural" data structures.
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01 Oct 2002 |
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XML Matters: Get the most out of gnosis.xml.objectify
The XML binding gnosis.xml.objectify was designed, in many ways, more as a toolkit than as a final tool. But this leaves some (potential) users confused about how to specialize it for some common tasks. In this article, David shows readers how very thin wrappers can customize gnosis.xml.objectify to perform actions such as: Provide XPath access to child objects; automatically reserialize objects to XML; modify the syntax of access to nodes. Some of these techniques involve rather trivial specialization of provided parent classes. Others involve small utility functions.
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23 Nov 2004 |
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XML Matters: On the 'Pythonic' treatment of XML documents as objects(II)
In the second installment of his new "XML Matters" column -- and as part of his ongoing quest to create a more seamless integration between XML and Python -- David Mertz presents the xml_objectify module. David describes how to use xml_objectify and the advantages of using this "Pythonic" module for working with XML documents as objects.
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01 Aug 2000 |
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XML Matters: Getting started with the DocBook XML dialect
In the third installment of his "XML Matters" column, David Mertz gets you started with DocBook, an SGML/XML dialect that describes the content of technical articles and other documents. David discusses the benefits of using DocBook, and then describes how to plan and modularize a large document conversion project.
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01 Oct 2000 |
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XML Matters: Ajax tradeoffs: The many flavors of XML
Ajax has become a familiar acronym for many Web developers these days, but it combines several very different techniques. One is the in-page manipulation of the DOM tree that was formerly known as Dynamic HTML. Another is the passing of data back and forth between the client and the server behind the scenes, without re-loading the page. The combination of these can make powerful Web applications which have many of the desirable features of desktop applications. The focus for now will be on just one group of related aspects: what format should the data exchange take?
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09 Jan 2007 |
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XML Matters: OASIS Election Markup Language
The Organization for the Advancement of Structured Information Standards (OASIS) has developed many XML standards in use within government, law, and business. Election Markup Language (EML) is OASIS' foray into the world of elections -- with an emphasis on voting within governmental jurisdictions. In this installment, David gives readers an introductory look at the structure and purpose of EML, with an eye toward how this standard, which is now used largely in Europe, will substantially influence future data standards in the United States.
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15 Oct 2004 |
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XML Matters: MochiKit
MochiKit is a useful and high-level library for JavaScript. MochiKit takes its main inspiration from Python, and from the many conveniences the Python standard library offers; but on the side it also smooths over the inconsistencies among browser versions. MochiKit.DOM is a particularly handy component that lets you work with DOM objects in much friendlier ways than raw"JavaScript provides. A lot of MochiKit.DOM is customized for XHTML work, which possibly makes its use of XHTML wrapped microformats particularly convenient when combining MochiKit and Ajax.
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21 Nov 2006 |
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XML Matters: Lighter than microformats: Picoformats
In a past installment of the XML Matters column, David Mertz explored reStructured Text, a lightweight markup language for formatting mostly text documents, and prior to that he looked at YAML, a lightweight markup language for mostly data documents. With the rise of Ajax and microformats, are these still useful, or are microformats "light" enough? As picograms are lighter than micrograms, we'll explore how lighter than lightweight" formats JSON (lighter than YAML) and reStructured Text (lighter than HTML) and the lightweight MochiKit library can be used for for AJAX without the X and for generating microformats.
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01 Aug 2006 |
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