Understanding > WebSphere Commerce and service-oriented architecture (SOA) > Data service layer > Data service layer query processing > Query template file
Commerce Feature Pack
Graph composer
In the query template file, an optional graph composer Java class can be specified in the ENTITY section within the PROFILE block. This Java class allows you to augment the final graph of physical SDOs. It can perform data aggregation from other sources and can merge multiple graphs of physical SDOs into a single graph if there is more than one associated SQL statement defined in the profile for the base table object.
The graph composer is needed for two-step queries that use multiple association SQL statements. You need to implement your own graph composer only if the result sets of the association SQL statements retrieve identical records from tables other than the base table.
If specified, the graph composer must subclass from the com.ibm.commerce.foundation.server.services.dataaccess.GraphComposer abstract class and implement the abstract composeGraph() method.
For example:
BEGIN_PROFILE
name=profileName1
BEGIN_ENTITY
entity_table=CATENTRY
<!-- must subclass from com.ibm.commerce.foundation.server.services.dataaccess.GraphComposer -->
<!-- used to compose the final graph -->
<!-- if more than one associated SQL statement defined -->
className=com.my.GraphComposer
associated_sql_statement=CatEntryWithDescription
associated_sql_statement=CatEntryWithProperty
END_ENTITY
END_PROFILE
Related tasks
Create an access profile for an existing XPath expression
Extending a default WebSphere Commerce query
Generating your XPath key using the wcs_xpathkey utility
Related reference
Data service layer naming conventions
WebSphere Commerce extended XPath notation
Last updated: 25 November 2009