Hypertext Templates

Hypermedia templates are defined as sets of pre-linked documents that can be duplicated [Catlin et al., 1991]. Another definition of a hypertext template states that it "is a partially-created, properly formatted collection of document skeletons that can be filled in by the user" [Rao & Turoff, 1990].

Templates automate the process of creating hypermedia collections by creating the "skeletons" of documents and linking them. They facilitate the design, organization, and presentation of a collection of knowledge in the form of hypertext.

The template can be considered as a composite object comprised of other objects such as nodes and links. The usage of a template will definitely speed up the process of an average user's understanding of the underlying hypertext model or the metaphor . Without a template, a hypertext author will have to start constructing the hypertext collection of ideas from the beginning. Many applications such as collaborative writing, teaching aids etc., have some common basis that can be transformed into a hypertext template.

The following are some requirements for a hypertext system to provide templates:

1. It should provide some generic operations to create, duplicate, edit or delete a template. Duplication should yield empty documents with nodes and links.
2. There should be facilities to add contents to empty documents, list templates and their constituent documents and links, to display an overview of the template, to access a template by its type ("get a copy of the planning template"), by author, or by creation date.
3. There should be control operations to displaying an overview of the template, to zoom into specific link sets or webs or sub graphs and look at the contents of documents.
4. Strategic choices must exist to find out the master template from which a duplicate was created and to edit the master template. Editing a master template should propagate the changes to all templates created from it.
5. Facilities should exist to specify formats and screen layouts for a template and to add help.
6. Reactive choices must be provided to directly manipulate the contents of documents within a template such as editing, deleting, creating new links etc.

Intermedia, developed at Brown University, provides the following features for hypermedia templates [Catlin et al., 1991]:

1. Intermedia system provides the facility to create templates including the documents and links that make up the template. That is, a hypermedia author has the ability to create nodes, links, and link sets or webs within a template. A list of webs can be associated with a template one of which can be chosen as the default when the template is duplicated.
2. Documents within the same template can be linked. Users can also link a document in a template to another document outside of the template.
3. The user can specify the folder or directory under which each document is created and also the folder where the template has to be duplicated. The user can also name and save a template for future use. The system will make copies of all folders and documents and automatically link them just as the original template was linked. All new documents will be displayed for the purpose of editing.
4. When a template is duplicated, all associated documents and links can be easily accessed in new folders. The user will be prompted to choose one of the webs associated with the template. The user can open a template, add document members, delete members, rename them, create or modify links etc. Contents of documents can be edited.
5. The user can easily find out which template was used to make a new hypermedia collection.
6. The original template itself is write-protected so that users do not edit it accidentally.

Researchers at Brown University believe that the ability to duplicate collections of linked material can be extended to other hypertext environments. Research is required in the area of propagating editing changes to documents that were created using a particular template. The concept of class-based templates needs exploration - templates should be able to inherit characteristics from other templates (similar to the concept of inheritance in object-oriented systems). With inheritance, when an author changes a parent template, all of its sub-classed templates would change accordingly.