Chapter 12

  1. Hypermedia is a combination of hypertext and multimedia. See slide 12-hypertext. Hypermedia interfaces are usually direct manipulation interfaces. They must support the display of a variety of media components and the anchors embedded in documents. Also, they must allow for following links in response to the activation of an anchor. See slide 12-direct.
  2. See slide 12-navigation. Support for navigation may be offered by selective traversal, based on attributes, content listings, indexes and, in a graphical manner, by maps displaying the information components and their connections.
  3. See slide 12-classification.
  4. Such a model is essentially based on the Dexter hypertext reference model. Important for hypermedia is the support for time-based documents and the synchronization between components. See slide 12-model.
  5. A link is a, possibly conditional, connection between a source anchor and a target anchor. An important distinction is that between structural links, which determine the hierarchical organization of the hyperdocument, and referential links, that may impose an arbitrary associative structure upon the document. Both anchors and links may be defined in a virtual way. The actual meaning of virtual links is computed when reading the document. Active documents are scripts that require computation to display their contents. Following links usually is the result of executing a procedure in response to an event or an action of the user.
  6. Just think of the time you have spent waiting for your program to compile.
  7. The problem of heterogeneous systems is essentially to combine multiple hybrid components in a seamless way. An object-oriented approach allows for employing techniques such as encapsulation by wrapping, refinement by inheritance and distributed application integration along the lines sketched in the OMG proposal. See slide 12-heterogeneous.
  8. Answer this question with some caution. You may want to write a paper about it.