Nuxeo CoreSession and Transactions

Getting a CoreSession in nuxeo

See also Nuxeo's more recent post about the topic.

• Through an event listener's context
• Through a Seam context
• Through a Restlet context
• By opening a repository manually
• Via an "UnrestrictedSessionRunner"
• Through the WebEngine context
• In tests: by dependency injection

Through an event listener's context

Any document event holds an event context which is a DocumentEventContext instance. It is then ensured to contain a CoreSession (not always the case with other event contexts). Example:

public class ServiceAPIListener implements EventListener {

    public void handleEvent(Event event) {
        EventContext ctx = event.getContext();
        if (!(ctx instanceof DocumentEventContext)) {
            return;
        }
        CoreSession session = ctx.getCoreSession();
        ....
    }
}

Through a Seam context

CoreSessions can be injected on a Bean, example:

@Name("easysoaImport")
@Scope(ScopeType.CONVERSATION)
@Install(precedence = Install.FRAMEWORK)
public class ScaImportBean {

    private static Log log = LogFactory.getLog(ScaImportBean.class);

    @In(create = true, required = false)
    CoreSession documentManager;

    ....
}

Through a Restlet request

Example from the EasySOA discovery API (in the easysoa-registry-rest bundle):

@Path("easysoa/discovery")
public class DiscoveryRest {

    @POST
    @Path("/appliimpl")
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
    @Produces(MediaType.APPLICATION_JSON)
    public Object doPostAppliImpl(@Context HttpContext httpContext, @Context HttpServletRequest request) throws Exception {
        CoreSession session = SessionFactory.getSession(request);
        ......
    }

}

By opening a repository manually

Example from org.nuxeo.ecm.platform.mail.listener.MailEventListener:

            // open a system session
            loginContext = Framework.login();
            RepositoryManager mgr = Framework.getService(RepositoryManager.class);
            Repository repository = mgr.getDefaultRepository();
            if (repository != null) {
                coreSession = repository.open();
            }

Note: other login() functions are also available, including login(String username, Object password).

In the case of events triggered by the scheduler (Quartz), the login part is unnecessary if you configured an username in your contribution.

Via an "UnrestrictedSessionRunner"

Create a class that extends org.nuxeo.ecm.core.api.UnrestrictedSessionRunner, then launch it by using the runUnrestricted() method. See for example the EasySOAInitComponent + DomainInit use:

      new DomainInit(defaultRepository.getName()).runUnrestricted();

public class DomainInit extends UnrestrictedSessionRunner {
    public DomainInit(String repositoryName) {
        super(repositoryName);
    }
    public void run() throws ClientException {
        DocumentModel root = session.getChildren(
                this.session.getRootDocument().getRef()).get(0);
        .....
    }
}

Through the WebEngine context

Any Resource registered by a WebEngineModule can access a WebContext object which holds a CoreSession.

In tests: by dependency injection

Use the @Inject annotation:

@RunWith(FeaturesRunner.class)
@Features(EasySOACoreTestFeature.class)
@RepositoryConfig(type=BackendType.H2, user = "Administrator", init=EasySOARepositoryInit.class)
public class DocumentServiceTest {
    @Inject DocumentService docService;
    @Inject CoreSession session;
    ....
}

Using & configuring transactions in Nuxeo :

Transactions can be configured in Nuxeo using following ways :

• in seam UI, jboss seam annotations @Transactional
• in webengine ui, one transaction around each UI request (session in view pattern), save if disabled or XML-configured otherwise on some URL patterns. See http://doc.nuxeo.com/display/NXDOC/Session+And+Transaction+Management
• in async events, AsyncEventExecutor execute a ReconnectedEventBundleImpl in its transaction thanks to EventBundleTransactionHandler, which uses TransactionHelper with custom retry & timeout.
• in services, @Transacted method annotation (used nowhere ??) : if TransactedServiceProvider is in use, Framework.getLocalService() will provide an instance of the service that is wrapped by a proxy by TransactedInstanceHandler.newProxy() that does a transaction (using TransactionHelper) around calls to @Transacted-annotated methods.
• in tests, TransactionalFeature. Uses TransactionHelper.

Additional helpers :

• TransactionHelper : explictly manage user transactions (Nuxeo's JTA Transaction manager's UserTransaction)
• TransactionalCoreSessionWrapper : Wrapper around a CoreSession that gives it transactional behavior (including events). Uses TransactionHelper.