Support multiple databases

[sunnyawake]

my company is investigating using Seam as our framework. one of the requests is supporting multiple databases for different customers with almost the same set of java code and pages.

i used the dvdstore sample and did the following changes:

1. changed all @PersistenceContext to @In
2. in AuthenticationAction,added a companyId field for login.xhtml. after authentication,outject the companyId to sessionContext.
3. changed components.xml:
......

 <persistence:managed-persistence-context auto-create="true"
  name="entityManager" />
  <persistence:managed-persistence-context auto-create="true"
  name="company1_em" />
  <persistence:managed-persistence-context auto-create="true"
  name="company2_em" />
<factory auto-create="true" name="order" scope="stateless" value="#{orderHome.instance}"/>
 <framework:entity-home auto-create="true"
  entity-class="com.jboss.dvd.seam.Order" name="orderHome" scope="conversation" entity-manager="#{platform.entityManager}">
  <framework:id>#{orderId}</framework:id>
 </framework:entity-home>
 <framework:entity-query ejbql="select c from Category c"
  name="allCategories" order="c.name" entity-manager="#{platform.entityManager}">
  
 </framework:entity-query>
 <factory name="topProducts" value="#{topQuery.resultList}"/>
 <framework:entity-query ejbql="select p from Product p" max-results="8"
  name="topQuery" order="p.inventory.sales desc" entity-manager="#{platform.entityManager}"/>

4. add Platform.java:

@Name("platform")
public class Platform {
     public static final String KEY_COMPANYID="com.longkey.system.companyId";
     public static final String SUFFIX_EM = "_em";
     public static final String SUFFIX_JBPMCONTEXT = "";
     public static final String SUFFIX_DATASOURCE = "_dvdDatasource";
     public static String[] getCompanyIds() {
          return new String[]{"company1","company2"};
     }
     public  EntityManager getEntityManager(){
          String companyId=(String)Contexts.getSessionContext().get(KEY_COMPANYID);
          return (EntityManager)Component.getInstance(companyId+SUFFIX_EM);
     }

5. changed ManagedPersistenceContext.java:
........

 @Create
   public void create(Component component)
   {
      this.componentName = component.getName();
      if(componentName.equals("entityManager")){
           
           componentName=Contexts.getSessionContext().get(Platform.KEY_COMPANYID)+Platform.SUFFIX_EM;
      }

6. in persistence.xml,jbpm.cfg.xml and xxx-ds.xml,added entries for each company. in hibernate.cfg.xml,commented out datasource property,which i specified in Jbpm.java when seam startup:

private void initJbpmConfiguration()
   {
      if (jbpmConfigurationJndiName==null)
      {
         jbpmConfiguration = JbpmConfiguration.getInstance();
      }
      else
      {
         try
         {
            jbpmConfiguration = (JbpmConfiguration) Naming.getInitialContext().lookup(jbpmConfigurationJndiName);
         }
         catch (NamingException ne)
         {
            throw new IllegalArgumentException("JbpmConfiguration not found in JNDI", ne);
         }
      }

      DbPersistenceServiceFactory defaultFactory = (DbPersistenceServiceFactory) jbpmConfiguration.getServiceFactory("persistence");
      if (Naming.getInitialContextProperties()!=null)
      {
         // Prefix regular JNDI properties for Hibernate
         Hashtable<String, String> hash = Naming.getInitialContextProperties();
         Properties prefixed = new Properties();
         for (Map.Entry<String, String> entry: hash.entrySet() )
         {
            prefixed.setProperty( Environment.JNDI_PREFIX + "." + entry.getKey(), entry.getValue() );
         }
         
         try
         {
            defaultFactory.getConfiguration().getProperties().putAll(prefixed);
         }
         catch (HibernateException he)
         {
            log.info("could not set JNDI properties for jBPM persistence: " + he.getMessage());
         }
      }
      //sunny build session factory for each company
      Configuration cfg=defaultFactory.getConfiguration();
      String[] companyIds=Platform.getCompanyIds();
      for(String companyId:companyIds){
           DbPersistenceServiceFactory factory = (DbPersistenceServiceFactory) jbpmConfiguration.getServiceFactory("persistence",companyId+Platform.SUFFIX_JBPMCONTEXT);
           factory.setConfiguration(cfg);
           cfg.setProperty(Environment.DATASOURCE, "java:/"+companyId+Platform.SUFFIX_DATASOURCE);
           factory.getSessionFactory();
      }
   }

after these changes, something weird happens. in AuthenticationAction the outjected currentUser is always lost somewhere before i reach the checkout page,which causes CheckoutAction.submitOrder throw exceptions and not be able to lauch OrderManagement workflow.

Seam:2.1.0.SP1,JBoss:4.2.3.GA