Use the EJB data mediator service for data access

The following steps use code samples to describe a simple instance of how to create the EJBs data mediator service (DMS) metadata.

 

1. A mediator instance is created using one of the create methods on the mediator factory (com.ibm.websphere.sdo.mediator.ejb.MediatorFactory) as in the following example

   import com.ibm.websphere.sdo.mediator.ejb.Mediator;
    import com.ibm.websphere.sdo.mediator.ejb.MediatorFactory;
    import com.ibm.webpshere.ejbquery.QueryException;
    import commonj.sdo.DataObject;
    try{
    String[] query =  { "select d.deptno,d.name from DeptBean as d" }; 
    Mediator m = MediatorFactory.getInstance().createMediator( query, null);
    DataObject root = m.getGraph();
   } catch (QueryException e) { ... } 
   

2. There are 3 different forms of the createMediator method. The arguments are explained as follows:

   createMediator( query, parms)  createMediator( query, parms, schema ) createMediator( query, parms, schema,  typeMap,  pattern)
   

   
   

   Table 1. createMediator method arguments

   String	query	array of EJB query statements
   Object	parms	values for input parameters of the query statements
   Eclass*	schema	the EClass of the root DataObject
   Map*	typeMap	a java.util.Map that maps EJB Abstract Schema Names from the query statement into Eclass names
   int*	pattern	the pattern used for containment
   * used only when using caller provided schema

Enterprise Java Beans Data Mediator Service

 

Related

DataGraph schema
Example: Using query arguments with EJB mediator