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Data Integration Guidelines

native formats and the translation happens just before the data either goes out 

to the external world or comes in from the outside. 

2. Use a facade approach and do programmatic object mapping in the DAO layer. 

That is, you set up a DAO to connect an EIS to the application server. Write 

the DAO so that it exposes only the canonical data model and have it map any 

incoming data to the appropriate internal data model. Since this approach con 

verts incoming data to the canonical form when the data arrives at the applica 

tion server, the business logic internally uses the canonical data representation.

To understand the XSL style sheet approach, let's consider how the adventure

builder enterprise receives invoices from various suppliers. In adventure builder's

case, various suppliers submit invoices, and each supplier may have a different

representation (that is, a different format) of the invoice information. Furthermore,

adventure builder's various EISs may each have a different representation of the

same invoice information. Code Example 6.6 shows an example of a typical sup 

plier's invoice.