TAL processor for hypermedia applications

Abstract

TAL (Template Authoring Language) is a specification language for hypermedia document templates. Templates describe application families with structural and semantic similarities. In TAL, templates not only define design patterns that applications must follow, but also constraints on the use of these patterns. A template must be processed together with a padding document giving rise to a new document in some specification language, called target language. TAL supports the description of templates independently of the languages used to specify target and padding documents. Usually a specific processor is required for each target language and for each padding document used. This paper concerns TAL processors. However, we should note that the proposal can be easily extended to any other solution used to define templates. Any pattern language and any language used to define constraints could be used instead of TAL. The TAL processor architecture is general and it is discussed when presenting the processor framework. As an instantiation example, an implementation of a TAL Processor targeting NCL (the declarative language of Ginga DTV middleware) is examined, and also another one targeting HTML-based middleware. The use of wizards for defining padding documents is also discussed in the examples of the proposed architecture instantiation.