Implementing Business Object Mediators to transform logical SDOs and physical SDOs
In this lesson,
you import read and change mediators
to transform the logical and physical SDOs. The Business Object Mediator
in the WebSphere Commerce Data Service Layer transforms between logical
SDOs, the Java implementation of a noun, and physical SDOs, a Java
representation of a database table. There are two types of mediators:
read mediators and change mediators. Read mediators transform the
physical representation of data, physical SDOs, to the logical representation,
logical SDOs. Change mediators translate actions on the logical SDOs
such as create, update, and delete, into operations on the physical
data.
About this task
A noun part is either a part of a noun, or by definition, can be a noun itself. Mediators are needed for each noun and each changeable noun part. To simplify development and maintenance of mediators, one noun can be sectioned into multiple changeable parts. It is recommended to use one mediator for each complex element in the noun, excluding any user data elements.
Breaking up your nouns into noun parts is a design decision that is based on your business logic requirements. In general, a software architect would refactor complex substructures in the noun into noun parts.
For this tutorial, the Project
noun is divided into the following noun parts:
- Description part
- Material part
- Tool part
- Instruction part
- Collection part
- Project part, which includes all other noun contents
The ProjectCollection noun is divided
into the following
noun parts:
- Description part
- ProjectCollection part, which includes all other noun contents
In this lesson, you import the following mediators:
Project
noun:
- ReadProjectDescriptionPartMediator
- Builds the Description part of the Project noun.
- ReadProjectMaterialPartMediator
- Builds the Material part of the Project noun.
- ReadProjectToolPartMediator
- Builds the tool part of the Project noun.
- ReadProjectInstructionPartMediator
- Builds the Instruction part of the Project noun.
- ReadProjectCollectionRelPartMediator
- Builds the Collection part of the Project noun.
- ReadProjectMediator
- Builds the remainder of the Project noun.
- ChangeProjectDescriptionPartMediator
- Updates the physical SDOs with the Description part of the Project noun.
- ChangeProjectMaterialPartMediator
- Updates the physical SDOs with the Material part of the Project noun.
- ChangeProjectToolPartMediator
- Updates the physical SDOs with the tool part of the Project noun.
- ChangeProjectInstructionPartMediator
- Updates the physical SDOs with the Instruction part of the Project noun.
- ChangeProjectCollectionRelPartMediator
- Updates the physical SDOs with the Collection part of the Project noun.
- ChangeProjectBasePartMediator
- Updates the physical SDOs with the remainder of the Project noun.
- ChangeProjectMediator
- Creates and deletes the Project noun.
ProjectCollection noun:
- ReadProjectCollectionDescriptionPartMediator
- Builds the Description part of the ProjectCollection noun.
- ReadProjectCollectionMediator
- Builds the remainder of the ProjectCollection noun.
- ChangeProjectCollectionDescriptionPartMediator
- Updates the physical SDOs with the Description part of the ProjectCollection noun.
- ChangeProjectCollectionBasePartMediator
- Updates the physical SDOs with the remainder of the ProjectCollection noun.
- ChangeProjectCollectionMediator
- Creates and deletes the ProjectCollection noun.
Read
mediators are responsible for constructing
a logical noun from the physical SDOs that represents the corresponding
entry in the database. Each read mediator contains a buildNoun method
(or buildNounPart) that has two parameters:
- Object aLogicalEntityType
- The logical noun (or noun part) to build.
- Object aPhysicalEntityType
- The physical SDO containing the unique ID of the noun.
- validateCreate, validateChange, validateDelete
- These methods are used to determine whether an action can proceed. For example, a validateChange method always checks if the noun to change currently exists in the database.
- create, update, delete
- These methods set the values of the logical noun into the physical SDOs representing the database tables.
- getNounPartXPaths
- This method returns the noun part that this mediator operates on, for example, /Description.
The WC_eardir\xml\config\com.mycompany.commerce.project\wc-component.xml file
defines the following data service configuration:
<_config:dataservice dataMediatorType="JDBC" metadataClass="com.mycompany.commerce.project.facade.server.metadata.ProjectMetadata"> </_config:dataservice>Complete the following steps to import the mediators.
Procedure
- Import the ProjectMetadata.java file:
- Expand Project-Server/ejbModule.
- Right-click com.mycompany.commerce.project.facade.server.metadata; click Import.
- Expand General; select File System, then click Next.
- Browse to the temporary location where you extracted the RecipeServices.zip file.
- Browse to the com.mycompany.commerce.project.facade.server.metadata folder; select the folder, then click Ok.
- Select ProjectMetadata.java; click Finish.
- Click Yes to overwrite any existing file.
- Import the com.mycompany.commerce.project.facade.server.services.dataaccess.bom.mediator
package:
- Expand Project-Server/ejbModule.
- Right-click com.mycompany.commerce.project.facade.server.services.dataaccess.bom.mediator; click Import.
- Expand General; select File System, then click Next.
- Browse to the temporary location where you extracted the RecipeServices.zip file.
- Browse to the com.mycompany.commerce.project.facade.server.services.dataaccess.bom.mediator folder; select the folder, then click Ok.
- Select all the files in the mediator folder; click Finish.
- Click Yes to All to overwrite any existing files.
- Import
the com.mycompany.commerce.project.facade.server.helpers package:
-
Type com.mycompany.commerce.project.facade.server.helpers in
the name field. Click Finish.
-
Type com.mycompany.commerce.project.facade.server.helpers in
the name field. Click Finish.