As a proof of concept project, I created a new site at TicketWarehouse.us. This site gives all information as XML files, converted to HTML with XSLT. A future improvement on the site will include some cross platform compatibility and other functionality. This site was developed for a few purposes, mainly as a proof of concept extensible platform, and also as a way to test how the different search engines crawl and process XML web sites, and a way to learn more about the technology.

As an experimental site, some of the links still point to our main site, and the navigation and overall design are simplistic, to say the least.

Please, take a look and let me know what you think of the site so far. The XML data the site is built on can be viewed using your browser's view source, and the XSLT template can be found at <xsl:value-of select="$title" />.

I look forward to your comments and suggestions, from areas of improvement for the design and navigation, to ways of improving the underlying code. This technology is still pretty new to me, but I'd like to get feedback and make sure I am not doing anything wrong or improper at this early stage.

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Very good.

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Dave Barnes
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Interesting. Should be interesting to hear your report on search engines crawl. In my view, that should not be any more difficult than crawling an HTML site. But may be it is too early for some SE to crawl and index it.

Or grab it in the page source.

1. You are a fast learner. Impressing site.
2. May be the next step should be defining your own XML Scema, so you learn how to get full control over your documents.
3. Then semanitc linking using XLink. You can transform XLinks to HTML links using XSLT if the browser is not XLink enabled. XPath, XPointer, XLink and XSL(T) are intimately connected.
4. AJAX functionality where DOM scripting is very important - the three layers of the web, content and information, presentation and styling and finally behaviour, animation and interactivity.
5. Usability and accessibilty. Single sourcing and multiple formats and presentations. KW's PDF documents, WAP, Screenreaders, ....

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Kjell Gunnar Bleivik:: Financial information at your fingertips
Learn object oriented programming where it started

I thank you for the comments and complements. I am still working on the site, experimenting with different things. I added a custom DTD, mostly as a way to keep track of the elements I am adding and removing from the different variants of the XML files, and I will see how that goes.

My new experiment is trying to make the site cross-platform. Unfortunately, there seem to be no cell phones that support XML+XSLT, so the transformation has to be done server side. This is a discovery I wish I had made before I developed an XSL template that could handle desktop and cell phone formats. I think the next step is to create a PHP script that can get the XML file and transform it according to the XSL template and return the resulting page to the client. Any advice on a method to do so using PHP? For instance, is that something I should be able to accomplish with an existing PHP library, or am I going to have to custom build a solution?

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I am not sure of what you mean here.

1. A web page is a bitstream (0,1)'s to a browsers. Does that imply that mobile browsers like Opera Mini don't yet support XML+XSLT?
2. Various XSLT transformations rely on third party or external libraries / parsers / proccessors that may be installed to function. Since AJAX have revitalized JavaSrcipt and DOM building a lot of JavaScript libraries have been implemented to support XML technologies. One example that I have not used myself is jQuery: The Write Less, Do More, JavaScript Library that also comes with a book. There are a lot of other libraries and new are made.
3. In addition there are XSLT extensions like EXSLT that some languages support. Note for example the important "regular expressions" extension.

PHP is my preferred language since it has a large community and is developing very fast.

1. When using PHP for XML DOM or HTML DOM transformations, it is important that you use the latest version of PHP. I think the current version is PHP 5.2.5.
2. PHP 5.* is important, since it is more a true OO program than it's predecessors. Not least the PHP Data Objects (PDO) extension encapsulates database connetction and makes it more secure and easy to use.
3. Many XML parsers and processors can be used with PHP, where the most advanced is the tree based DOM parser. The other major tree based PHP parser is SimpleXML. The two major stream based PHP parsers are SAX XML and XMLReader. The major avdvantage with the most advanced DOM parser is that you have (nearly) complete control of the XML Node tree in the memory of the server. The most important advantage with stream based parsers is that they are much more efficient when it comes to memory usage. If fast processing and efficient processing is important, stream based parsers should be used if it is possible. If you need full flexibility, the XML DOM should be used. Sometimes it is enough to use SimpleXML that is easier to learn and use.
4. Note, some parsers / processors requires that PHP is recompiled with the processor module or that external libraries like
   - ftp://xmlsoft.org/libxml2/
   - Downloads
   are installed. You find more if you scroll down on RedCarpetRank - Webs outstanding sites, resources and articles

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Kjell Gunnar Bleivik:: Financial information at your fingertips
Learn object oriented programming where it started

Figures, Opera Mini is the one browser I didn't test on. Most of the default web browsers are not yet ready for XML+XSLT it seems, as they simply return an unrecognized format error when presented with an XML file. Openwave for example. Opera Mini does handle the site very well, with a server side browser detection that transforms the XSLT document depending on the browser.

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The best way to learn anything, is to question everything.

I will especially draw your attention to the zXML library for cross-browser XML, XPath, and XSLT support.

Link: NCZOnline - Downloads

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Kjell Gunnar Bleivik:: Financial information at your fingertips
Learn object oriented programming where it started

Having done some more testing on the site and research into different mobile browsers, I have found that currently, no mobile platform acknowledges that they support XML+XSLT, which makes the process more difficult, and has me back to server-side browser sniffing.

I have found that Google can crawl almost any link in an XML+XSLT site, be it a link contained in the XML file itself or a link generated by the XSLT stylesheet. This seems to me pretty impressive considering how uncommon this technology is at this time.

After doing some more research into this method of developing sites, which seems completely designed for the purpose of allowing a single XML file to be redisplayed on a variety of platforms, there seems to be a surprising lack of any way to specify different XSLT templates for different platforms. In fact, there seems to be no way to accomplish this.

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The best way to learn anything, is to question everything.

I have a proposal to you, email Opera and link to this post before Google come up with their own browser that will monopolize the browser market. We need competition and Google has a clear advantage, since they can start from scratch and follow the W3C standards. See my next comment. Foregive me this loppying on behalf of a small company that I think have been hurt by some large companies. And it should be relevant, since OpreaMini is rated high internationally or am I wrong?

That was what I expected and why Google increase their lead in the SE market.


If you by platfrom mean browser, again, contact Opera. Their browser is as far as I know in the front on making a full XML family compatible browser. And may be they have a solution already or will incorporate it in Version 10 of the full version and do it better than many other companies for the mobile market.

Try
KW + processor
KW + parser
KW + interpreter

You may need to recompile and / or relink PHP + a PHP processor if you use that for server scripting.

Have you searched on the W3C site generally and on the Mobile site specially?

Read what I write here: Logistics (The first section).

I can highly reccomend the book mentioned there:

"Dr. Erik Wilde and Dr. David Lowe has written a good book that describes this theory in greater detail.
XPath, XLink, XPointer, and XML: A Practical Guide to Web Hyperlinking and Transclusion Addison Wesley ISBN: 0201703440"

That book may be 5 to 10 years ahead of time, and you have to reread it. Those persons are far ahead of many of us. I am sure you only get a touch of the top of the iceberg of what they are working with (read chapter 9 "Transforming to a New Model") if you buy the book.

Section 8.4.3 "Link Semantics" with code example is worth the price of the book. It is about converting XLinks to HTML links before XLink is a standard used by the most important browsers.

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Kjell Gunnar Bleivik:: Financial information at your fingertips
Learn object oriented programming where it started

I actually opened a thread on the Opera site (Media Type for XML+XSLT Sites - Opera Mini - Opera Community) hoping to find out that there is simply a different media type I would need to specify to get the page to display in Opera Mini. Unfortunately, it seems that Opera is the only browser that supports the media tag, causing the page to break in Internet Explorer or Firefox, due to the two browsers diametrically opposed implementations of XSLT. For IE, whichever template I specify first is used, and Firefox uses the last specified template.

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The best way to learn anything, is to question everything.

If you intend to display the xml data in a mobile browser, why not just write a template that'll convert it to WAP or WML for the Openwave, Nokia and Opera mini browsers as well as most PDA's.

It's a hassle to learn WAP and WML but once you've set up your template(s), you'll be good to go.

As may have already been stated, you can test your wml using the regular Opera browser and you can download the Openwave and Nokia SDK's for testing your WAP pages.

Don't worry too much about developing specifically for the Motorola browser as their SDK's are notoriously buggy. Essentially, if your pages work in the Openwave and Nokia browsers, they should be good to go.

Openwave Developer Network - Tools & SDK - Openwave Phone Simulator

In addition to providing an SDK, forum Nokia is a pretty good resource as well:
Forum Nokia - Web Technologies

You're using a browser detect to determine which content to serve up, right?

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Actually, um, no. Being that this is a purely experimental site, right now the site only serves raw XML, hoping that the client will be able to download the correct template to display the page. Unfortunately, the only browsers that seem to be fully compatible with this technology are the Opera browsers. Openwave and Nokia do not support XML, at least on their respective emulators. I am using a small amount of server-side scripting to allow the site to display properly in IE and Mozilla, but my ultimate goal is to have the site work across browsers client side. Sadly, it seems this capability is a ways off.

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The best way to learn anything, is to question everything.

I thought you had tried to use XSL (XSTL or XML-FO) to transform the XML file to WAP or WML.

It shall be possible, but I have never tried it myself.

Using XSTL or XML-FO you can transform and XML document to whatever format you want as long as there are processors, libraries or parsers.

That is what the concept of single-souring is all about.

One single XML source file, many presentations / applications.

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Kjell Gunnar Bleivik:: Financial information at your fingertips
Learn object oriented programming where it started