Thus, in
this example it is impossible to understand if the person lives in the city or if the
person works in the city. OEM uses edge labels to describe the pointed nodes, and
thus edges represent only the containment relationship.
In Damiani and Tanca (1997), the authors propose a graph-oriented description and
query language specifically designed for the needs of Web sites (WG-Log). WGLog
allows one to represent classical conceptual objects and standard hypermedia
design notations, allowing the expression of model entities and relationships as well
as navigational concepts. The WG-Log data model uses directed labeled graphs to
represent schemata, instances, and queries. In WG-Log graphs, nodes represent objects,
and edges indicate relationships between them. In particular, in WG-Log two
main node types are defined: simple and complex nodes. Simple nodes represent
simple objects (with an atomic, perceivable value as strings and numbers), while
complex nodes represent abstract objects (whose properties are described by means
of aggregates of simple objects). For example, a person is represented by means of
a complex node Person, and the person??™s name by means of a simple node Name
with a value. Moreover, there are other kinds of nodes to describe indexes and entry
points, useful for the representation of the hypermedia structure.
Pages:
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518