Thesis full text (PDF) - Politecnico di Milano

• Structural Model: The structural model expresses the data content of the site. The content
is expressed in terms of relevant entities and relationships (Figure 2.1.a). WebML is
compatible with classical notations like Entity Relationship (E-R) model [16], the ODMG
object-oriented model [17] and UML class diagram [18].
• Hypertext Model: The hypertext model can be published in the site. Different hypertext
defines different site view (Figure 2.1.b). The site view consist two sub models:
o Composition Model: It specifies which page composes the hypertext and which
content units make up a page. There are six different types of units available to
build up a page. The units are following: data, multi-data, index, filter, scroller
and direct units. Composition units are defined on the top of the structure schema
of the site. The developer/designer indicates the underlying entity or relationship
on which the content of each unit is based. For example in figure 2.1.b, the “Book
Data”, “Author Data” data unit are showing the information of a book, refer the
“Book” and “Author” entity is specified in the schema of figure 2.1.a.
o Navigation Model: Navigation model describes how the pages and the content of
the units are connected or linked to form the hypertext. There are two kinds of
links – non-contextual and contextual. Non-contextual links are used when they
connect semantically independent pages. For example, the page of a book to the
home page of the site. On the other hand, the contextual links are used when the
content of the destination unit of the link depends on the content unit of the source
unit. For instance, the page showing a book’s data in linked by a contextual link
of the page showing the index of edition of books of that book. Contextual links
are based on the structure schema because they connect content units whose
underlying entities are associated by the relationships in the schema.
• Presentation Model: Presentation model expresses the layout of the pages and graphic
content of each page. Presentation specifications are either page-specific or generic.
• Personalization Model: Users and user groups are explicitly modeled in the structure
schema in the form of predefined entities namely – User and Group. The features of these
entities can be used for storing group-based or individual content like shopping
suggestion, list of favorites etc. This personalized information can be used both in the
composition of units or in the definition of presentation specifications. On the other hand,
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