90

Designing a Service's Interaction Layer

E

Before delegating these incoming client requests to the Web service business 

logic, you should perform any required security validation, transformation of 

parameters, and other required preprocessing of parameters. 

As noted in  Parameter Types for Web Service Operations  on page 72 and

elsewhere, Web service calls are basically method calls whose parameters are

passed as either Java objects, XML documents (

javax.xml.transform.Source

objects), or even SOAP document fragments (

javax.xml.soap.SOAPElement

objects).

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For parameters that are passed as Java objects (such as 

String,

int

, JAX RPC 

value types, and so forth), do the application specific parameter validation and 

map the incoming objects to domain specific objects in the interaction layer 

before delegating the request to the processing layer.

You may have to undertake additional steps to handle XML documents that

are passed as parameters. These steps, which are best performed in the interaction

layer of your service, are as follows:

1. The service endpoint should validate the incoming XML document against its 

schema. For details and guidelines on how and when to validate incoming 

XML documents, along with recommended validation techniques, refer to 

 Validating XML Documents  on page 139.

2. When the service's processing layer and business logic are designed to deal

with XML documents, you should transform the XML document to an inter 

nally supported schema, if the schema for the XML document differs from the

internal schema, before passing the document to the processing layer. 

3. When the processing layer deals with objects but the service interface receives 

XML documents, then, as part of the interaction layer, map the incoming XML 

documents to domain objects before delegating the request to the processing 

layer. For details and guidelines on mapping techniques for incoming XML 

documents, refer to  Mapping Schemas to the Application Data Model  on 

page 143.

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It is important that these three steps validation of incoming parameters or 

XML documents, translation of XML documents to internal supported sche