The Gist

Mallard development has been a bit dormant lately. A few features have trickled in over the last year, but the backlog of things to improve has been steadily growing. But things are looking up. I’m nearly done moving projectmallard.org to my Linode, which will allow me to finally fix the broken mailing list archives. Then I can finalize some specifications and release actual packages for the schemas, thus ending this two-year yak-shaving exercise.

This post will highlight some of the back-burner Mallard projects that I hope to get traction on. To help the progress, I’m considering having a virtual quackfest where a handful of people work on specifications, tutorials, and implementations. You don’t have to be a programmer to get involved. Sometimes all we need are experienced Mallard users to give input and try new ideas. If you’re interested, leave a comment, or email me at shaunm at gnome dot org.

Here’s an overview of what I hope to address in the near future:

Mallard 1.1

Mallard 1.0 is finished, despite the admonition on the specification that it’s still a draft. We’ve gotten a lot of feedback, and seen what works and what doesn’t for extensions. (It works more than it doesn’t.) Mallard 1.1 will address that.

• Support a tagging mechanism. The very rough Facets extension defines a tagging mechanism that it uses to match pages. But tagging has uses outside faceted navigation, so we should move this into the Mallard core.
• Allow info elements in formal block elements. This allows you, for example, to provide credits for code snippets and videos. It’s also necessary to support the next bullet item:
• Let formal block elements participate in automatic linking. People have asked to be able to link with a finer granularity than pages and sections. There are good implementation reasons why Mallard doesn’t allow arbitrary anchors, but I believe we can link to certain well-defined endpoints.
• Allow sections IDs be optional. This is a common gotcha, and I think it’s a restriction we can relax.
• Allow comments after sections. This is another common gotcha. Comments are just block content, and it doesn’t make much sense to put block content after sections. I think we can special-case comments.
• Allow the links element to override the link role. This is a bit esoteric, but very useful in some cases.
• Let informational links be one-way only. Sometimes it’s handy to opt out of automatic link reciprocation.
• Provide a sort of static informational link type. This would allow you to assemble groups of links with no other semantics that you can still format with the links element.
• Move hi out of experimental. Yelp has supported an experimental element to highlight some text for a very long time. It’s useful. It should be standard.
• Allow link grouping for section links. I’m not sure on the best implementation for this yet, but the feature is useful.
• Provide a generic div element with an optional block title. This is useful for extensions. We’d want to slightly redefine block fallback behavior to make this really useful. This is a somewhat backwards-incompatible change, but I think the risk is minimal.
• Provide a way to do automatic links through tags. Sometimes you have a collection of pages that you want to link together. Mallard’s automatic links are one-to-one, so they make this case only marginally better. We may be able to hook into the tagging mechanism to do automatic links to all pages with a matching tag.
• Allow multiple desc elements, with the exact same semantics as multiple informational titles.

Mallard UI

The Mallard UI extension is intended to hold extensions that add some user interactivity without additional semantics. Currently, expanders are fully defined and implemented. We have experimental implementations for media overlays and link thumbnails, and a plan for tabbed sections.

Mallard Sync

The Mallard Sync extension is planned to allow you to syncronize videos with text content. There are only rough ideas at this point. It will allow things like action links to seek in a video, showing and highlighting parts of the document as a video plays, and tables of contents for videos.

Mallard Conditionals

The Mallard Conditionals extension provides a runtime conditionals mechanism. Content can be conditionally shown based on things like the target platform, the reading environment, the supported Mallard features of the processing tool, and the language of the content. This is well-defined and fully implemented as it is. It just needs a thorough audit to finalize it.

There are other test token schemes that I’d like to work on:

• Check the current page or section ID.
• Check for page or sections IDs that exist in the document.
• Check the tag values for the page.

All of these help with reuse. They allow you to XInclude standard content that can adapt itself to different pages and documents.

Mallard API

I did some work on an extension that allows you to format automatic links as API synopses when doing API documentation. I briefly mentioned this in my blog post API Docs on Mobile. This still needs a lot of work, and it needs input from people who are used to working with API documentation in different programming languages.

Mallard Glossaries

I blogged before about an extension to do automatic glossaries in Mallard. It’s been collecting dust for a while.

Faceted Navigation

I also blogged before about an extension to do faceted navigation in Mallard. It’s been collecting dust for an even longer while.

Mallard+TTML, Mallard+SVG, Mallard+MathML, Mallard+ITS

You can add W3C-standard formats like TTML, SVG, MathML, and ITS to your Mallard document. I’ve blogged about Mallard+TTML Video Captions, and there’s a tutorial on Mallard and SVG. These are all implemented, and they work extremely well thanks to Mallard’s well-defined extension mechanism. But they’d all be a lot better with a specification and a schema.

As you can see, there’s a lot to work on. Mallard was designed to be a platform from which we could explore new ideas for help. I think it’s proven itself in that regard. But as with any open source project, it needs an investment from people to keep driving it forward.

I’ve recently been talking with Petr Kovar about how to make language packs for videos work well with Mallard. Petr, Jakub Steiner, and others have been working on a video-intensive “Getting Started” document for GNOME. Videos, of course, can take up a lot of disk space very quickly, and the problem is compounded when we localize into dozens of languages, as we do in GNOME.

I suggested making language packs for videos. So, for example, the Czech videos would be in a package called gnome-getting-started-cz. But you can’t expect people to use the software center to install the language pack on their own before viewing some introductory videos. Fortunately, we have a mechanism to install packages directly from a help document, using install action links.

<note>
<p>Install a language pack to view vidoes in your language.</p>
<p><link action="install:gnome-getting-started-cz" style="button">Install<link></p>
</note>


This works nicely when viewed locally in Yelp, but it doesn’t work so well when the document is built to HTML for the web. We can use Mallard Conditionals to make the note only visible when install action links are available.

<if:if test="action:install"
xmlns:if="http://projectmallard.org/if/1.0/">
<note>
<p>Install a language pack to view vidoes in your language.</p>
<p><link action="install:gnome-getting-started-cz" style="button">Install<link></p>
</note>
</if:if>

And while we’re at it, we really don’t want this note showing up when you view the original English source document, so we can refine the conditional with some language tokens:

<if:if test="action:install !lang:C !lang:en"
xmlns:if="http://projectmallard.org/if/1.0/">
<note>
<p>Install a language pack to view vidoes in your language.</p>
<p><link action="install:gnome-getting-started-cz" style="button">Install<link></p>
</note>
</if:if>

This is almost right, except that we’ve hard-coded the package name for the Czech language pack. We want to be able to translate the package name in the action attribute. If you use itstool to translate your Mallard document with PO files, it turns out the package name will be in a translatable message, but embedded in markup in a way that translators won’t like:

msgid "<link action=\"install:getting-started-cz\" style=\"button\">Install</link>"

Worse yet, if you use Okapi to translate your document with XLIFF files, it won’t appear at all. Okapi and itstool are both based on the W3C Internationalization Tag Set (ITS), and this is a case where I think ITS really shines. We can use local overrides and embedded ITS rules to instruct these tools on exactly what to offer for translation.

For convenience, define these two namespace prefixes on the page element:

xmlns:mal="http://projectmallard.org/1.0/"
xmlns:its="http://www.w3.org/2005/11/its"

To make segmentation clearer (especially for itstool), mark the link as non-translatable. This makes sure the action attribute doesn’t just get segmented with the rest of the containing paragraph. But we do want to translate the content of the link, so add a span that is translatable:

<p><link action="install:gnome-getting-started-cz" style="button" its:translate="no">
<span its:translate="yes">Install</span><link></p>

With itstool, you’ll now get the nicer no-markup message in your PO file:

msgid "Install"

But now we want to be able to translate the action attribute. Of course, we can’t add an its:translate attribute to the attribute. XML just doesn’t work that way. So we have to use embedded global rules to mark it is translatable. And while we’re at it, we can also provide a localization note for translators. Put this in the info element of the page:

<its:rules version="1.0">
<its:translateRule selector="//mal:link/@action" translate="yes"/>
<its:locNoteRule selector="//mal:link/@action" locNoteType="description">
<its:locNote>Translate this to install:getting-started-LL, replacing LL
with your locale, only if there is a video translation pack for your
locale.</its:locNote>
</its:locNoteRule>
</its:rules>


You’ll now get this in your PO file:

#. Translate this to install:getting-started-LL, replacing LL with your
#. locale, only if there is a video translation pack for your locale.
msgid "install:getting-started-cz"

This is the kind of thing that’s possible when you have a dynamic help format, an integrated local help viewer, a run-time conditional processing system, and a translation process based on powerful industry standards. And it’s why I still love XML.