DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports Events Over 2 million developers have joined DZone. Join Today! Thanks for visiting DZone today,
Edit Profile Manage Email Subscriptions Moderation Admin Console How to Post to DZone Article Submission Guidelines
View Profile
Sign Out
Refcards
Trend Reports
Events
Zones
Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Partner Zones AWS Cloud
by AWS Developer Relations
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Partner Zones
AWS Cloud
by AWS Developer Relations
The Latest "Software Integration: The Intersection of APIs, Microservices, and Cloud-Based Systems" Trend Report
Get the report
  1. DZone
  2. Data Engineering
  3. Databases
  4. Connecting to Multiple Databases Using Hibernate

Connecting to Multiple Databases Using Hibernate

Taha Siddiqi user avatar by
Taha Siddiqi
·
Mar. 07, 12 · Interview
Like (3)
Save
Tweet
Share
98.42K Views

Join the DZone community and get the full member experience.

Join For Free

In a recent project, I had a requirement of connecting to multiple databases using hibernate. As tapestry-hibernate module does not provide an out-of-box support, I thought of adding one. https://github.com/tawus/tapestry5

Now that the application is in production, I thought of writing a simple “How to”.

I have cloned the latest stable(5.3.2) tapestry project at

https://github.com/tawus/tapestry5

and have added multiple database support to it.

Single Database

It is almost fully compatible with the previous integration when using a single database except for a few things

1) HibernateConfigurer has changed

public interface HibernateConfigurer
{
   /**
    * Passed the configuration so as to make changes.
    */
   void configure(Configuration configuration);

   /**
    * Factory Id for which this configurer is meant for
    */
   Class<? extends Annotation> getMarker();

   /**
    * Entity package names
    * 
    * @return
    */
   String[] getPackageNames();
}

2) There is no HibernateEntityPackageManager, as the packages can be contributed by adding more HibernateConfigurers with the same Markers.

Multiple databases

For multiple database, a marker has to be used for accessing Session or HibernateSessionManager

@Inject
@XDB
private Session session;

@Inject
@YDB
private HibernateSessionManager sessionManager;

@XDB
@CommitAfter
void myMethod(){

}

Also you have to define a HibernateSessionManager and a Session for the secondary database in the Module class.

@Scope(ScopeConstants.PERTHREAD)
@Marker(DatabaseTwo.class)
public static HibernateSessionManager buildHibernateSessionManagerForFinacle(
    HibernateSessionSource sessionSource,
    PerthreadManager perthreadManager)
{
    HibernateSessionManagerImpl service = new HibernateSessionManagerImpl(sessionSource,
        DatabaseTwo.class);

    perthreadManager.addThreadCleanupListener(service);

    return service;
}

@Marker(DatabaseTwo.class)
public static Session buildSessionForFinacle(
    @Local HibernateSessionManager
        sessionManager,
    PropertyShadowBuilder propertyShadowBuilder)
{
    return propertyShadowBuilder.build(sessionManager, "session", Session.class);
}

Notice an annotation @DatabaseTwo.class. This is a Factory marker and is used to identify a service related to a particular SessionFactory.

@Retention(RetentionPolicy.RUNTIME)
@Target( {ElementType.FIELD, ElementType.PARAMETER, ElementType.METHOD})
@FactoryMarker
@Documented
public @interface DatabaseTwo
{

}

A typical AppModule for two databases will be

public class AppModule
{

    public static void bind(ServiceBinder binder)
    {
        binder.bind(DemoService.class, DemoServiceImpl.class);
    }

    @Contribute(HibernateSessionSource.class)
    public static void configureHibernateSources(OrderedConfiguration<HibernateConfigurer>
        configurers)
    {
        configurers.add("databaseOne", new HibernateConfigurer()
        {
            public void configure(org.hibernate.cfg.Configuration configuration)
            {
                configuration.configure("/databaseOne.xml");
            }

            public Class<? extends Annotation> getMarker()
            {
                return DefaultFactory.class;
            }

            public String[] getPackageNames()
            {
                return new String[] {"org.example.demo.one"};
            }
        });

        configurers.add("databaseTwo", new HibernateConfigurer()
        {
            public void configure(org.hibernate.cfg.Configuration configuration)
            {
                configuration.configure("/databaseTwo.xml");
            }

            public Class<? extends Annotation> getMarker()
            {
                return DatabaseTwo.class;
            }

            public String[] getPackageNames()
            {
                return new String[] {"org.example.demo.two"};
            }
        });
    }

    @Contribute(SymbolProvider.class)
    @ApplicationDefaults
    public static void addSymbols(MappedConfiguration<String, String> configuration)
    {
        configuration.add(HibernateSymbols.DEFAULT_CONFIGURATION, "false");
        configuration.add("tapestry.app-package", "org.example.demo");
    }


    @Scope(ScopeConstants.PERTHREAD)
    @Marker(DatabaseTwo.class)
    public static HibernateSessionManager buildHibernateSessionManagerForFinacle(
        HibernateSessionSource sessionSource,
        PerthreadManager perthreadManager)
    {
        HibernateSessionManagerImpl service = new HibernateSessionManagerImpl(sessionSource,
            DatabaseTwo.class);

        perthreadManager.addThreadCleanupListener(service);

        return service;
    }

    @Marker(DatabaseTwo.class)
    public static Session buildSessionForFinacle(
        @Local HibernateSessionManager
            sessionManager,
        PropertyShadowBuilder propertyShadowBuilder)
    {
        return propertyShadowBuilder.build(sessionManager, "session", Session.class);
    }

}

Injecting into Services

You can inject a session in a service using the marker. As DatabaseOne is being used as the default configuration, in order to inject its Session, you have to annotate it with @DefaultFactory. For DatabaseTwo, you can use @DatabaseTwo annotation.

public class DemoServiceImpl implements DemoService
{
    private Session sessionOne;

    private Session sessionTwo;

    public DemoServiceImpl(
        @DefaultFactory Session sessionOne,
        @DatabaseTwo Session sessionTwo)
    {
        this.sessionOne = sessionOne;
        this.sessionTwo = sessionTwo;
    }

    @SuppressWarnings("unchecked")
    public List<EntityOne> listOnes()
    {
        return sessionOne.createCriteria(EntityOne.class).list();
    }

    @SuppressWarnings("unchecked")
    public List<EntityTwo> listTwos()
    {
        return sessionTwo.createCriteria(EntityTwo.class).list();
    }

    public void save(EntityOne entityOne)
    {
        sessionOne.saveOrUpdate(entityOne);
    }

    public void save(EntityTwo entityTwo)
    {
        sessionTwo.saveOrUpdate(entityTwo);
    }
}


Using @CommitAfter

You can add an advice the same way you used to. The only change is in @CommitAfter. You have to additionally annotate the method with the respective marker.

public interface DemoService
{
    List<EntityOne> listOnes();

    List<EntityTwo> listTwos();

    @CommitAfter
    @DefaultFactory
    void save(EntityOne entityOne);

    @CommitAfter
    @DatabaseTwo
    void save(EntityTwo entityTwo);
}

Here is an example.

 

From http://tawus.wordpress.com/2012/03/03/tapestry-hibernate-multiple-databases/

Database Hibernate

Opinions expressed by DZone contributors are their own.

Popular on DZone

  • Full Lifecycle API Management Is Dead
  • Spring Boot vs Eclipse MicroProfile: Resident Set Size (RSS) and Time to First Request (TFR) Comparative
  • Custom Validators in Quarkus
  • Multi-Cloud Integration

Comments

Partner Resources

X

ABOUT US

  • About DZone
  • Send feedback
  • Careers
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 600 Park Offices Drive
  • Suite 300
  • Durham, NC 27709
  • support@dzone.com
  • +1 (919) 678-0300

Let's be friends: