Category Archives: ProXist

ProXist v2

For the last few days, I’ve been busy updating ProXist, my XProc abstraction layer and app for eXist. There is a new(-ish) XProc package for eXist that promises to support a lot of (Norm Walsh’s XProc engine) Calabash’s capabilities, so I decided it was time to test it out and do a new ProXist at the same time.

My XML Prague ProXist version supported only my custom document type and stylesheets, and barely those at that. It was meant to be a demo. For the new version, though, I’m thinking of doing a default implementation for DocBook, including some of the more commonly used stylesheets and a couple of standard pipelines, packaged so they can be used with ProXist–it should be a question of writing a ProX blueprint XML file, theoretically, plus something that helps me list DocBook resources included using XInclude.

At the same time, I’m finally updating the ProXist documentation. It’s written using DocBook, incidentally, and now part of the git repository.

ProXist is not even close to being finished, but at least I seem to have moved on from procrastinating to actually doing something.

I Should Probably…

Following this year’s Balisage conference, I should probably do a rewrite and update of the whitepaper I presented. It’s on my list of things to do.

On the other hand, I should do an eXist implementation of the version handling system I suggested in that paper. It’s also on my list of things to do.

But then again, I still have to finish my ProXist implementation, the one I presented at XML Prague. It is (you guessed it) on my list.

I have lots of good (well, I think so) ideas first presented at XML conferences, many of which deserve (well, I think so) to live beyond them. After all, a lot of work goes into the papers and the presentations, so shouldn’t I follow up on them more?

My version handling system, for example, should be easy enough to do in eXist. It doesn’t require a revolution, it doesn’t require me to learn how to code in Java, it should be enough to spend a couple of nights writing XQueries and XSLT to produce a usable first version.

ProXist is both simpler and more difficult to finish, but on the other hand, the basic application is already out there and works. It’s a question of rewriting it to be easier for others to test, which basically means redoing it as a standard eXist app.

Yet, instead of doing something about either of them, here I am, writing this blog post. It’s conference procrastination taken to yet another level.

And the next XML Prague deadline is coming up fast.

ProXist Documentation, Etc

My XProc abstraction thingy for eXist, ProXist, is not the most well-documented open source project there is, but at least there is now something to read. It’s little something in DocBook, just a first draft and terribly incomplete, but something that I’m hoping to make more complete, given enough time.

I also feel it’s time to ProXist it as an eXist app rather than a set of misplaced collections.

This Year’s XML Prague…

…was fabulous. It always is, don’t get me wrong, but this one was the best yet. It’s all on video at the conference website, which, all things considered, is a pretty decent substitute for being otherwise engaged, but Prague this time of year is the XML capital of Europe and the place to be.

For one thing, I think I finally actually understand some of the streaming part of the up-and-coming XSLT 3.0 spec, thanks to Abel Braaksma and Michael Kay, who both presented papers on the subject.

John Lumley presented a paper on lessons learned when finalising a standard library for XSLT/XPath extensions to manipulate binary data, a brilliant talk.

George Bina showed oXygen on mobile devices with the crowd cheering his every swipe of the iPad screen, in what was probably one of the most memorable demos ever at XML Prague.

And there was me, lastly (literally; I was the last scheduled speaker, right before a concluding interactive talk led by Robin Berjon), showing my ProXist demo. It all went surprisingly well, except for a slight problem with Linux and Gnome.

You should have been there.

Oh, and…

…most of the ProX stuff is available at Github. Not the eXist web pages, yet, but that’s because I’m still experimenting with them and there’s some work left. There’s the Balisage demo, and there’s the basic ProXist stuff, with pipelines and XQueries and such, and there’s the authoring environment (with Relax NG schema, FO, etc), but no instructions on how to get any of it to run, yet.

I have a test app running locally, a little something that is about as simple as I can make it, but since I am not a web developer (I’m a markup geek), the HTML is awkward, the CSS nonexistent apart from the default eXist stuff, and the XQueries somewhat painful. I do think it’s going to be pretty cool, though, and look forward to presenting it at XML Prague.

ProXist and My XML Prague Paper

I recently submitted the final version of my XML Prague whitepaper about my eXist implementation of ProX, called ProXist (with apologies for the tacky name). While I’m generally pleased with the paper, the actual demo implementation I am going to present at the conference is not quite finished yet and I wish I had another week to fill in the missing parts.

Most of the ProXist stuff works but there are still some dots to connect. For example, something that currently occupies the philosophical part of my brain has to do with how to run the ProX wrapper process, the one that configures the child process that actually does stuff to the input. ProX, so far, has been very much about automation and about things happening behind the scenes, and so I have aimed for as few end user steps as possible.

My Balisage ProX demo was a simple wrapper pipeline that did what it did in one go. Everything was fitted inside that pipeline: selecting the input, configuring the process that is to be applied to the input in an XForm, postprocessing the configured process and converting it to a script that will run the child process, running the child process, saving the results. Everything.

But the other day, while working on the eXist version and toying with its web application development IDE, it dawned on me that there doesn’t have to be a single unified wrapper process. If its components are presented on a web page and every one of them includes logic to check if the information from a required step is available or not (for example, a simple check to confirm that an input has been chosen before the process can be configured), they don’t have to be explicitly connected.

The web page that presents the components (mainly, selecting input and configuring the process to be applied on the input) then becomes an implicit wrapper. The user reads the page and the presentation order and the input checks are enough. There is no longer a need a unified wrapper process.

Now, you may think this is obvious, and I have to admit that it now seems obvious to me, too. But I sometimes find it to move from one mindset (for example, that automation bit I mentioned, above) to another (such as the situation at hand, the actual environment I implement things in) as easily as I would like. If this is because I’m getting older or if it’s who I am, I don’t know. In this particular case, I was so convinced that the unified wrapper was the way to go that it got in the way of a better solution.

At least I think it’s a better solution. If it isn’t, hopefully I can change my mind again and in time.

See you at XML Prague.


I’ve been working on an eXist-based implementation of my XProc abstraction layer, ProX, hoping to have something that runs before XML Prague, next month. It turns out that the paper I submitted on the subject has been accepted, so now I guess I just have to.

The ProX implementation should not be terribly complicated to finish, but until recently it risked to be rather hackish (is that a word?) because the XMLCalabash eXist module written by Jim Fuller was rather primitive: it would only support pointing out the pipeline to run and one, hard-coded output port. I foresaw a more or less complete rewrite of the ProX wrapper in XQuery.

Luckily, Jim very graciously agreed to rewrite his module into something more immediately usable. I received the first updated module to test in December and the most recent update just a few days ago. He also found a bug in Calabash’s URI handling and sent a first fix to me along with the updated module. There are still things to do but for me, Christmas came really early this year.

Oh, and I’m calling the implementation, and the paper, ProXist. Sorry about that.