Are (TCDL) Transformers a supported extension point?

Question

A 'standard' Tridion Deployer configuration contains TCDL Transformers for pages and component presentations, which typically convert language neutral TCDL markup into web app specific code (like JSP or ASP.NET):

<Module Type="ComponentPresentationDeploy" Class="com.tridion.deployer.modules.ComponentPresentationDeploy">
    <Transformer Class="com.tridion.deployer.TCDLTransformer" />
</Module> 
<Module Type="PageDeploy" Class="com.tridion.deployer.modules.PageDeploy">
    <Transformer Class="com.tridion.deployer.TCDLTransformer"/>
</Module>

I guess its possible to add your own custom or extended Transformer, but is this supported?

The (potential) use case I have is to resolve TCDL links into static URLs at deployment time using the linking API. This would be required when publishing to a system which (for various reasons) is not capable of using dynamic linking in published pages.

Answer 1

Of course. It's documented too, albeit as more of an outline than a complete walkthrough:

Creating custom TCDL tags

You can find more information in the Content Delivery API documentation, available on this page:

API reference documentation downloads

Answer 2

To my knowledge TCDL Transformers always have been a supported extension point, they came around in R5.3 I guess and were promoted in the beginning. Later the com.tridion.tcdl.TagHandler and com.tridion.tcdl.TagRenderer extension points were added and those appear to be promoted currently through the documentation.

In your case, you want to transform a tag during publishing/deployment, so you can create a class that implements the interface com.tridion.tcdl.TagHandler.

If you would want to transform this tag at request time (for use by the Web service), then you would create a class that implements the interface com.tridion.tcdl.TagRenderer.