Chapter 4 XML Processing

163

4.3.8 Design Recommendation Summary

When you design an XML based application, specifically one that is a Web service,

you must make certain decisions concerning the processing of the content of incom 

ing XML documents. Essentially, you decide the  how, where, and what  of the pro 

cessing: You decide the technology to use for this process, where to perform the

processing, and the form of the content of the processing.

In summary, keep in mind the following recommendations:

E

When designing application specific schemas, promote reuse, modularization, 

and extensibility, and leverage existing vertical and horizontal schemas.

E

When implementing a pure object centric processing model, keep XML on the 

boundary of your system as much as possible that is, in the Web service in 

teraction layer closest to the service endpoint, or, for more classical applica 

tions, in the presentation layer. Map document content to domain specific 

objects as soon as possible.

E

When implementing a document centric processing model, consider using the 

flexible mapping technique. This technique allows the different components of 

your application to handle XML in a way that is most appropriate for each of 

them.

E

Strongly consider validation at system entry points of your processing 

model specifically, validation of input documents where the source is not 

trusted.

E

When consuming or producing documents, as much as possible express your 

documents in terms of abstract 

Source

 and 

Result

 objects that are independent 

from the actual XML processing API you are using.

E

Consider a  meet in the middle  mapping design strategy when you want to 

decouple the application data model from the external schema that you want to 

support.

E

Abstract XML processing from the business logic processing using the XML 

document editor design strategy. This promotes separation of skills and inde 

pendence from the actual API used.