Hi, I am using hibernate 3.2 and I try to implement the "session per request" paragdim with the org.hibernate.context.ThreadLocalSessionContext .

I don't understand as well the difference between openSession() and getCurrentSession() methods of the SessionFactory class.

I know that the session returned by openSession() is not attached to the current thread while the one return by getCurrentSession is. But the 2 session seems to be in different states. For example, the following code works fine :



and this one don't work :


In the second piece of code I have to open a transaction to run my query. This is not necessary in the first one.

How can I execute a query using the second way without opening a transaction?

Thanks for reply.

My apologies for my english.

Any idea?.....

Sorry if I say something too obvious. openSession retrieves a newly created sesion, while getCurrentSession gets the last sesion created with openSession (if you didn't close it). The second is a cheaper option, as it reuses the session (The session stores in session cache all objects used, so that less database access are required if you access the same object twice within the same session)

Thank you for the reply.

Ok Rober2D2, I am agree with you.

I just don't understand the difference of state between the two instances. I want to implement the "session per request" pattern using the ThreadLocalSessionContext class.

When I do "openSession()" or "getCurrentSession()" in a new thread I got a new session. How to put the two session in the same state?

Doing this test :



I have the results :

with openSession() :

active : false
open : true
connected : true

with getCurrentSession() :

active : false
open : true
org.hibernate.HibernateException: isConnected is not valid without active transaction
at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:297)
at $Proxy0.isConnected(Unknown Source)
at org.apache.jsp.Public.test_jsp._jspService(org.apache.jsp.Public.test_jsp:49)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:99)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:325)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:245)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)

I don't now how to open the connection without opening a transaction....

I don't know the exact difference between the two methods. It seems that openSession initializes something in the session, so it must be called once per Thread to get a new session. Once you've called openSession within a Thread, you may call getCurrentSession as many times as needed.

And something I read in the ThreadLocalSesionContext docs:



http://www.hibernate.org/hib_docs/v3/ap ... ntext.html

Actually, I think you just call getCurrentSession(), if you want to do the thread bound thing, and it will make a new session if one doesn't currently exist. Its a completely different thing that openSession().

I suspect that if you call openSession() first, it creates a normal session. If you then call getCurrentSession(), it creates another new session and binds it to the thread. Then if you call getcurrentSession() subsequent to this, it will return that thread bound session.

Also, I think all of your work is supposed to occur with in the bounds of a transaction, so you should probably be manually creating the transaction even with the openSession() method. I'm kind of suprized that it seems to be automatically making one for you. Perhaps you have another transaction manager configured in your environemnt that hibernate will automatically pick up on, i.e. JTA.