Information Technology Reference
In-Depth Information
Figure 3.
Merlyn in the Briar Rose Room.
The agent operates in a split-frame window of a Web browser. The up-
per frame, occupying most of the window, contains the current site's content.
The lower frame holds JavaScript code for interfacing between the agent, the
visitor, and the site, and displays buttons the visitor can use to command the
agent. The agent's architecture (its intelligence, behaviors, and annotation han-
dling) is written in Java. Hooks to the Microsoft Agent API are used to provide
the animated character and speech synthesis. The lower frame persists as the
user navigates the Web, so while the agent is an extra layer of interface beyond
the standard browser, it does not prevent the user from visiting any Web sites,
whether or not they are annotated.
Web annotations are represented in the Extensible Markup Language
(XML). Every page on an annotated site has a corresponding XML file con-
taining its annotations. Whenever a user visits a new page on the site, the guide
agent requests the annotation file from the server, parses it, and adds that in-
formation to its local store. If there are no annotations available, or if they are
useful only to other kinds of annotation-sensitive agents with different abilities
or goals, the agent can still fall back on its built-in repertoire of behaviors. The
agent does not require that the annotations be there, but it will make use of
them if they are.
