Database Server Models for WMS and WFS Geographic Web Services - Geographical Information Systems: Trends and Technologies - page 148

<Metamodel>
MOF

<<instantiate>> <<instantiate>>

Real World

Real World

<Metamodel>
Metamodel
CSL X

<Metamodel>
Metamodel
CSL Y

Application
Domain
Model B

Application
Domain
Model A

<<instantiate>>

<<instantiate>>

<Model>
Conceptual
Schema A
(PIM)

<Model>
Conceptual
Schema B
(PIM)

Formal mapping

Conceptual
Schema Mapping

PIM>PSM Mapping

<<derive>>

<<derive>>

<<derive>>

<Model>
Logical/Physical
Schema A
(PSM)

<Model>
Logical/Physical
Schema B
(PSM)

GML App.
Schema

Schema
Translation

Encoding <<derive>>

<<instantiate>> <<instantiate>>

GML
Instance
Document

Database A,
Transfer format A

Database B,
Transfer format B

:Instance
Translation

Fig. 3. Model- driven approach.

model, description of an application domain with a conceptual language
and then derivation of the schema into various dialects.
The mdWFS proposition handles the storage/delivery of conceptual
schemas and the semantic transformations depending on translation
models. The fi rst step is a semantic transformation. The second step is the
confi guration of a standard WFS service (OGC 2010b) to provide a data
exchange service. The standard WFS service is parameterized with the
destination data model but delivers data from the initial database. The WFS
service must be able to store data and provide several conceptual schemas.
OGC specifi cations should be extended.
A conceptual language, UMLT, is introduced for two main purposes:
the data representation and the semantic transformations. This cartographic
conceptual language is defi ned upon an independent extension of the
UML2 meta-model. Elements of the language are specifi ed with a UML2
model as a heritage of Activities. The textual notation of the language is
defi ned by a set of grammatical rules (EBNF—Extended Backus Naur Form).
Table 1 presents the extensions of the WFS specifi cations. Table 2 presents
the elements of the UMLT language.