Monday, May 25, 2009

Template Engine - Why Bother? XML + XSLT

I am not sure I read the entire recent "war" in the PHP general mailing list about the best PHP Template Engine Option but, generally speaking, this argument is truly loads of solutions and controversial opinions. Here I am with mine.

PHP 5 And In Core DOM, XML and XSLT

Apparently, all these "Smarty adorers" did not consider that PHP 5 introduced a lot of core classes to work over DOM, XML, and transform them via XSL files. Nothing to do, they prefer to move an entire template application rather than use the best native, fast, in core, solution. Here a couple of reasons to generally prefer XML and XSL Transformations rather than whatever engine, specially those written in PHP itself, a not that fast interpreted programming language.

Think Portable

Apparently developers like to be stuck forever in a single programming language, something I cannot even try to consider, since Information Technology means Flexibility and Updates. An extremely valid point to choose XML as output, and XSL as Transformer, is the universality of the XML markup language first, and complete separation between data and business logic from its presentation after.
Something PHP developers often look for, discarding without a valid reason what is already there since ages. Even if the entire website or application programming language will change (performances anybody?), rather than simply take care about how to reproduce the same XML via the new language, they prefer to recreate for each sub-part of the website the code to make that completely new and different template engine work. This becomes even more ridiculous when arguments are like:
if I need php in the middle of the presentation layer, I simply put it there ...
... "good thinking", isn't it?

Think Scalable

First of all, XML can be easily cached without even moving a single database connection. Moreover, having zero dependencies from external engines probably based on the same XML + XSLT concept, could simply make our application faster. XML has thousands of implementations, libraries, and fast parsers, for every kind of programming language and latest dabases could even interact directly with stored XML (or retrieve data directly in XML, did you know that?)
An application that as main intermediate layer has XML will have so many long therms advantages hard to imagine, are you still thinking a foreach inside the layout is a good solution?

Think About Your Career

Ok, I use PHP and I want a template engine that will bring me nothing new to learn, except its own PHP exposed API. And tomorrow, when I'll move into another better structured company, everything about XML, XSL(T), and XPath, will be a non-sense, "'cause I know peeaichpee", isn't it?
If you think you know enough about XML and XSLT and you are not using these layers I bet you do not truly know them or real potentials.
I bet you do not know XPath, you do not know how to generate a valid XHTML/HTML layout, and you do not know XSLT strategies to retrieve only info you want to show and nothing else.
Well, think about this, more enterprise ready stuff, rather than just whoevercanuseit programming language (easy to start, hard to use properly, that's PHP) ... is it an extra plus to at least give them a try?

Extreme Performances? A concrete Example

The New York Times website is using these technologies since ages and it implemented its own XSL Cache Extension in order to obtain best performances with xsl documents. At the same time, XSLT is present in every browser, included Internet Explorer 5 so it is even possible to simply delegate transformation to the client, speeding up even more the server. Here a simple example, based on my "old" JXON proposal.

Do you still think there are so many better options?

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