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Readability of XML Documents

Bill Venners: <?xml version="1.0" standalone="yes"?><deepquestion>To what extent is XML suitable for tasks in which humans, not just software, will be reading the documents?</deepquestion>

Elliotte Rusty Harold: <?xml version="1.0" standalone="yes"?><thoughtfulresponse>I think XML is clearly suitable for both tasks. I wrote an entire book in XML using a text editor. I wrote the next book in OpenOffice Writer, a traditional GUI word processor. I think the first book, written in XML, was much easier to write. <shamelessplug>Processing XML with Java</shamelessplug> was written in DocBook using JEdit, BBEdit, and UltraEdit -- plain vanilla text editors with no understanding of XML whatsoever. And I think that worked well for me. Certainly it works well for a developer, somebody with a developer's mind. Would I necessarily give this to a secretary and ask them to write XML? Maybe not, but I have known secretaries who spent their day typing TeX. And certainly XML is easier to use than TeX.</thoughtfulresponse>

Bill Venners: <?xml version="1.0" standalone="yes"?><sizematters>I have no problem reading the small XML documents that I have for each HTML page on my web site. They are flat XML documents with a dozen or so elements for the title, subtitle, author, and so on. I edit those files by hand with vi mostly, and it works great. On the other hand, I tend to get lost in Ant files. When I look up how to do something with Ant, the syntax often seems hairy and difficult. XML doesn't seem as natural to me as a traditional context free grammar. I think people sometimes use XML in places where a traditional context free grammar would be better.</sizematters>

Elliotte Rusty Harold: <?xml version="1.0" standalone="yes"?><syntaxmatters>You can certainly develop an obfuscated syntax in XML, a syntax that is hard to read -- just as you can in other languages. <obfuscatedsyntax><And>Just</And> <he>putting</he> <slams>something</slams> <the>into</the> <point>XML</point> <home>does</home> <with>not</with> <an>automatically</an> <innovative>make</innovative> <self-referential>it</self-referential> <example>clear</example></obfuscatedsyntax>. But I think in general with sufficient effort and care and thought, you can design XML formats that are plausible to read and plausible to understand.</syntaxmatters>

Next Week

Come back Monday, September 15 for the next installment of a conversation with C# creator Anders Hejlsberg. The final installment of this conversation with Elliotte Rusty Harold will appear September 22. If you'd like to receive a brief weekly email announcing new articles at Artima.com, please subscribe to the Artima Newsletter.

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Have an opinion about the design principles presented in this article? Discuss this article in the News & Ideas Forum topic, The Human Side of XML.

Resources

Elliotte Rusty Harold is author of Processing XML with Java: A Guide to SAX, DOM, JDOM, JAXP, and TrAX, which is available on Amazon.com at:
http://www.amazon.com/exec/obidos/ASIN/020161622X/

XOM, Elliotte Rusty Harold's XML Object Model API:
http://www.cafeconleche.org/XOM/

Cafe au Lait: Elliotte Rusty Harold's site of Java News and Resources:
http://www.cafeaulait.org/

Cafe con Leche: Elliotte Rusty Harold's site of XML News and Resources:
http://www.cafeconleche.org/

JDOM:
http://www.jdom.org/

DOM4J:
http://www.dom4j.org/

SAX, the Simple API for XML Processing:
http://www.saxproject.org/

DOM, the W3C's Document Object Model API:
http://www.w3.org/DOM/

ElectricXML:
http://www.themindelectric.com/exml/

Sparta:
http://sparta-xml.sourceforge.net/

Common API for XML Pull Parsing:
http://www.xmlpull.org/

NekoPull:
http://www.apache.org/~andyc/neko/doc/pull/

Xerces Native Interface (XNI):
http://xml.apache.org/xerces2-j/xni.html

TrAX (Tranformation API for XML):
http://xml.apache.org/xalan-j/trax.html

Jaxen (a Java XPath engine):
http://jaxen.org/

RELAX NG:
http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=relax-ng