Example 8.15 Implementing Session Facade - Session Bean

package corepatterns.apps.psa.ejb;

import java.util.*;
import java.rmi.RemoteException;
import javax.ejb.*;
import javax.naming.*;
import corepatterns.apps.psa.core.*;
import corepatterns.util.ServiceLocator;
import corepatterns.util.ServiceLocatorException;

// Note: all try/catch details not shown for brevity.

public class ProjectResourceManagerSession
  implements SessionBean {

  private SessionContext context;

  // Remote references for the
  // entity Beans encapsulated by this facade
  private Resource resourceEntity = null;
  private Project projectEntity = null;
  ...

  // default create
  public void ejbCreate() 
  throws CreateException {
  }

  // create method to create this facade and to
  // establish connections to the required entity
  // beans
  // using primary key values
  public void ejbCreate(
    String resourceId, String projectId, ...)
  throws CreateException, ResourceException {

    try {
      // locate and connect to entity beans
      connectToEntities(resourceId, projectId, ...);
    } catch(...) {
      // Handle exceptions
    }
  }

  // method to connect the session facade to its 
  // entity beans using the primary key values
  private void connectToEntities (
    String resourceId, String projectId)
  throws ResourceException {
    resourceEntity = getResourceEntity(resourceId);
    projectEntity = getProjectEntity(projectId);
    ...
  }

  // method to reconnect the session facade to a
  // different set of entity beans using primary key
  // values
  public resetEntities(String resourceId,
    String projectId, ...)
  throws PSAException {

    connectToEntities(resourceId, projectId, ...);
  }

  // private method to get Home for Resource
  private ResourceHome getResourceHome()
  throws ServiceLocatorException {
    return ServiceLocator.      getInstance().getHome(
        "ResourceEntity", ResourceHome.class);
  }

  // private method to get Home for Project
  private ProjectHome getProjectHome()
  throws ServiceLocatorException {
    return ServiceLocator.      getInstance().getHome(
        "ProjectEntity", ProjectHome.class);  
  }

  // private method to get Resource entity
  private Resource getResourceEntity(
    String resourceId)   throws ResourceException {
    try {
      ResourceHome home = getResourceHome();
      return (Resource) 
        home.findByPrimaryKey(resourceId);
    } catch(...) {
      // Handle exceptions
    }
  }

  // private method to get Project entity
  private Project getProjectEntity(String projectId)
  throws ProjectException {
    // similar to getResourceEntity
    ...
  }

  // Method to encapsulate workflow related
  // to assigning a resource to a project.
  // It deals with Project and Resource Entity beans
  public void assignResourceToProject(int numHours)
  throws PSAException {

    try {
      if ((projectEntity == null) ||
          (resourceEntity == null)) {

        // SessionFacade not connected to entities
        throw new PSAException(...);
      }

      // Get Resource data
      ResourceVO resourceVO =
          resourceEntity.getResourceData();

      // Get Project data
      ProjectVO projectVO =
        projectEntity.getProjectData();
      // first add Resource to Project
      projectEntity.addResource(resourceVO);
      // Create a new Commitment for the Project
      CommitmentVO commitment = new
        CommitmentVO(  ...);

      // add the commitment to the Resource
      projectEntity.addCommitment(commitment);

    } catch(...) {
      // Handle exceptions
    }
  }

  // Similarly implement other business methods to
  // facilitate various use cases/interactions
  public void unassignResourceFromProject()
  throws PSAException {
    ...
  }

  // Methods working with ResourceEntity
  public ResourceVO getResourceData()
  throws ResourceException {
    ...
  }

  // Update Resource Entity Bean
  public void setResourceData(ResourceVO resource) 
  throws ResourceException {
    ...
  }

  // Create new Resource Entity bean
  public ResourceVO createNewResource(ResourceVO 
    resource)   throws ResourceException {
    ...
  }

  // Methods for managing resourceÕs blockout time
  public void addBlockoutTime(Collection blockoutTime) 
  throws RemoteException,BlockoutTimeException {
    ...
  }
  
  public void updateBlockoutTime(
    Collection blockoutTime)   
  throws RemoteException, BlockoutTimeException {
    ...
  }
  
  public Collection getResourceCommitments() 
  throws RemoteException, ResourceException {
    ...
  }

  // Methods working with ProjectEntity
  public ProjectVO getProjectData()
  throws ProjectException {
    ...
  }

  // Update Project Entity Bean
  public void setProjectData(ProjectVO project) 
  throws ProjectException {
    ...
  }

  // Create new Project Entity bean
  public ProjectVO createNewProject(ProjectVO project)
  throws ProjectException {
    ...
  }

  ...

  // Other session facade method examples

  // This proxies a call to a Value Object Assembler
  // to obtain a composite value object.
  // See Value Object Assembler pattern
  public ProjectCVO getProjectDetailsData()
  throws PSAException {
    try {
      ProjectVOAHome projectVOAHome = (ProjectVOAHome)
        ServiceLocator.getInstance().getHome(
          "ProjectVOA", ProjectVOAHome.class);
      // Value Object Assembler session bean
      ProjectVOA projectVOA = 
          projectVOAHome.create(...);
      return projectVOA.getData(...);
    } catch (...) {
        // Handle / throw exceptions
    }
  }

  // These method proxies a call to a ValueListHandler
  // to get a list of projects. See Value List Handler 
  // pattern.
  public Collection getProjectsList(Date start, 
  Date end) throws PSAException {
    try {
      ProjectListHandlerHome projectVLHHome = 
        (ProjectVLHHome)
          ServiceLocator.getInstance().getHome(
            "ProjectListHandler",
            ProjectVLHHome.class);
      // Value List Handler session bean
      ProjectListHandler projectListHandler = 
        projectVLHHome.create();
      return projectListHandler.getProjects(
                    start, end);
    } catch (...) {
        // Handle / throw exceptions
    }
  }

  ...

  public void ejbActivate() {
    ...
  }

  public void ejbPassivate() {
    context = null;
  }

  public void setSessionContext(SessionContext ctx) {
       this.context = ctx;
  }

  public void ejbRemove() {
    ...
  }
}