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Designing XML Based Applications

fines transformations on the internal schema to support the external schemas.

3. An  in to out  approach, or legacy adapter This approach is actually about 

how to map an application data model to schemas. The developer designs the 

exposed schema from an existing data model. 

Figure 4.4, Figure 4.5, and Figure 4.6 show the sequencing of the activities

involved at design time and the artifacts (schemas and classes) used or produced

by these activities. The figures also show the relationships between these artifacts

and the runtime entities (documents and objects), as well as the interaction at

runtime between these entities.

The first approach (Figure 4.4), which introduces a strong dependency

between the application's data model and logic and the external schemas, is suit 

able only for applications dedicated to supporting a specific interaction model. A

strong dependency such as this implies that evolving or revising the external

schemas impacts the application's data model and its logic.

Design time

XML

Schema

(1) Design Data 

Model Classes

Data Model 

Classes

Runtime 

 XML 

Data Model 

Document 

Objects

Figure 4.4

Out to In Approach for Mapping Schemas to the Data Model Classes