Understanding data conversion

Bidirectional converters are used to mediate the data from a specific integration layer to the presentation layer. The following conversions are in place:

• From UI wrapper objects to SDO objects and back again, implemented through SDOConverter.java
• From UI wrapper objects to Web service Transfer Objects and back again, implemented through TOConverter.java

Considerations related to converting data:

• Wrapper classes (derived form UIWrapper) are simple POJO classes
• A centralized registry (MDMServerRegistry.java) is used to identify the necessary communication layer for every InfoSphere® MDM Server service call
• A reference to the original integration layer object is preserved in the wrapper class
• A cloning method is in place as a utility functionality

The UIWrapper classes are structurally a mirror of Web service Transfer Objects. Very few modifications are applied, as shown in the following table:

There is a naming convention that allows you to associate the wrapper classes with their corresponding business object:

• The wrapper class name is prefixed with UI
• The com.ibm.mdm.bobj package contains the current collection of wrapper classes
• Every wrapper class associated with an InfoSphere MDM Server business object is derived from the com.ibm.mdm.bobj.UIWrapper class

Metadata driven conversion is done to match the wrappers to corresponding SDO objects and Transfer Objects in the following XML configuration files:

• SDOConversions.xml
• TOConversions.xml

The following is an example of SDOConversions.xml content:

<TOConversionContexts>
	<TOConversionContext mdmServiceName="addProductInstance" 	mdmServiceInvocationParamTO=
"com.ibm.mdm.product.service.to.Product" mdmServiceRetrievedTO=
"com.ibm.mdm.product.service.to.Product"  mdmServiceRetrievedUIWrapper=
"com.ibm.mdm.bobj.product.UIProduct"/>
	…….
</TOConversionContexts>

The following is an example of TOConversions.xml content:

<SDOConversionContexts>
	<SDOConversionContext 
		mdmServiceName="getAllProductTypes" mdmServiceInvocationParamTO="" mdmServiceRetrievedTO="com.dwl.admin.ProductTypeBObjType" mdmServiceRetrievedUIWrapper="com.ibm.mdm.bobj.product.UIProductType"/>
	....
</SDOConversionContexts>
<AlternativeSDOFieldNames>
	<AlternativeSDOFieldName 
		sdoClassName="com.dwl.admin.ProductTypeBObjType" sdoFieldName=
     "ProductTypeName" uiWrapperClasName="com.ibm.mdm.bobj.product.UIProductType" uiWrapperFieldName="Name"/>
	....
</AlternativeSDOFieldNames>

<EncapsulateSDOFields>
	<MapSDOToUIWrapper 
sdoClassName="com.dwl.admin.SpecFormatBObjType" uiWrapperClassName="com.ibm.mdm.bobj.UISpecFormat">
<EncapsulateSDOField 
	sdoFieldName="SpecFormatId" uiWrapperClassName=
  "com.ibm.mdm.bobj.UISpecFormatTranslation" uiWrapperFieldName="SpecFormatId"/>
		....
	</MapSDOToUIWrapper>
	....
</EncapsulateSDOFields>

As the SDOConversions.xml sample content shows, there are two additional sections in the SDO .xml file that deals with structural differences between SDO objects and Transfer Objects.

• AlternativeSDOFieldNames/AlternativeSDOFieldName—This metadata is used when SDO objects and transfer objects have the same object graph structure, but do not have the same class name and field name. Its attributes are defined as follows:
  • sdoClassName —Specifies the name of an SDO class/interface
  • sdoFieldName —Specifies the name of an SDO class field name
  • uiWrapperClassName —Specifies the name of a UIWrapper class
  • uiWrapperFieldName —Specifies the name of a UIWrapper class field name
• EncapsulateSDOFields/MapSDOToUIWrapper—This metadata is used when SDO objects and Transfer Objects have a different object graph structure. The MapSDOToUIWrapper tag is used to identify the UIWrapper class associated with the corresponding SDO class. It has the following attributes and sub tag:
  • sdoClassName —Specifies the name of an SDO class or interface
  • uiWrapperClassName —Specifies the name of a UIWrapper class
  • EncapsulateSDOField —Specifies the a sub tag and used to associate a SDO class field name with the corresponding UIWrapper field name (due to existing structural differences between SDO objects and Transfer Objects we can run into such scenarios). It has following attributes:
    • sdoFieldName —Specifies the name of an SDO class or interface
    • uiWrapperClassName —Specifies the name of a UIWrapper class encapsulating the field name corresponding to the sdoFieldName
    • uiWrapperFieldName —Specifies the name of a UIWrapper class field name associated with the value of the sdoFieldName