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Outline for Handling XML Documents

4.2

Outline for Handling XML Documents 

An XML based application, and in particular a Web service application, may

consume or produce XML documents, and such an application may implement

three distinct processing phases: 

1. The application consumes an XML document.

2. The application applies its business logic on information retrieved from the

document.

3. The application produces an XML document for response.

Generally speaking, an XML based application exposes an interface that is

defined in terms of the schemas for the XML documents that it consumes and pro 

duces as well as by the communication or interaction policies of the application.

In the case of a Web service, a Web Services Description Language (WSDL) doc 

ument describes this interface, and this document refers to the XML schemas to

which the exchanged documents conform.

Let's examine the steps for handling XML documents. (See Figure 4.1.) The

first phase, consuming XML incoming documents or XML input processing, con 

sists of the following steps:

1.

Parse and optionally validate the document

 Parse and validate the incom 

ing document against the schema to which the document should conform.

2.

Transform the document

 If necessary, transform the document from its

conforming schema to the internally supported schema.

3.

Disassemble the document or pass it as is to the next phase

 Disassembling

a document consists of these steps:

I

Search the incoming document for relevant information. The information 

can be recognized by using the embedded tags or its expected location within 

the document.

I

Extract the relevant information once it is located.

I

Optionally, map the retrieved information to domain specific objects.