What you describe is provided by XSL and XHTML! These are both standard web technologies, albeit not particularly popular ones. This is how you define a templat

What you describe is provided by XSL and XHTML! These are both standard web technologies, albeit not particularly popular ones. This is how you define a template: <xsl:template match="put the xpath query for your components name here"> Anything inside that template will be expanded when you use your component's name in your XHTML file, either by the web browser or (more practically in an HTML5 world) by a server-side XSL processor. It's pretty fun :)