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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