I have argued here repeatedly that building applications using Microsoft Word's Custom XML feature is a spectacularly bad idea, but it turns out that I missed the best reason of all not to use custom XML: It may well be going away very soon, because, I gather, it infringed someone's patent. In reaction to this news, Tim Bray is reiterating his case that rolling your own XML is a bad idea:
People like me, who had experience with the extreme difficulty of doing this kind of customization, the extremely limited number of places where it made sense, and the high proportion of failure among people who tried to do it, shouted “That’s a bug!” Given that the number of organizations that deploy Office is huge, I bet Microsoft can trot out a few customers who’ve got good results with Custom XML. But I also bet that, first of all, the proportion who try is tiny and, second, that among those who do, few succeed in getting much business value.
I'm one of these people like Tim and like him, I told you so. Let's revisit some of this:
Earlier this year I agreed with Glyn Moody that using custom XML in a collaboration between Science Commons and Microsoft was promoting lock-in to Word 2007 and later versions. If the feature is removed from future versions then would MS Research like to consider the suggestion I made in March to embed ontological annotations using links. The ontology plugin in question used the simplest of schemas, so simple that there was really no need for custom XML at all.
I have also expressed doubts about the usefulness of a more complicated plugin that also comes out of Microsoft Research; Article Authoring Add-in for Microsoft Office Word 2007. This was supposed to let you author documents that were complaint with the complex NLM document Schema using Word. Again, it would have worked to lock documents to Word 2007 but I also found it to be pretty well unusable, and having seen a few of these classes of application over the years I didn't give it much chance of survival in the wild. Now, I guess its future is in doubt, and I'd still love to find the resources to try NLM authoring using the ICE system or a similar style-based system. I'm assuming that MS won't be under an injunction to drop styles support any time soon, although they havedone their best to bury them under the new user interface and make it less likely that people will use them.
I counselled my colleagues at Cambridge working on the Chem4Wordplugin to be cautious, citing lock-in, usability and maintainability. I wonder if they have heard anything about what might happen to this tool now? (I still think the best approach would be to use OLE to embed the chemical editor and simple features like links, fields and styles for the rest, which would mean that the tool could interoperate between different word processors including older versions of Word).
So, if Microsoft is going to pull Custom XML out of Word, at least in the USA, then I was right, it was a trap, it just turned out to have even nastier teeth than I thought. Now, I'd be really happy to have our group help any creators open source academic word processor plugins that have been snared. We're happy to share our experience on how to build interoperable, simple, robust authoring tools.
Copyright Peter Sefton, 2009. Licensed under Creative Commons Attribution-Share Alike 2.5 Australia. <http://creativecommons.org/licenses/by-sa/2.5/au/>