session.isConnected() ?

lakshmi_raga · **Joined:** Wed Feb 07, 2007 4:34 am **Posts:** 8

Hi All,

What exactly does session.isConnected() do?

when i call this api on the session object returned from a newSession using sessionFactory.openSession()

>>it prints true.

does it say whether this session object has a jdbc connection opened?

But if so, hibernate doc says that, a connection to a database is obtained and sql statements are triggered only when a transaction is commited or before some hql query.

moreover it states that, creating sessions is inexpensive, so this means that creating new session does not immedeately obtain a connection to a database otherwise how session creation is inexpensive.

Can somebody demistify this.

Thanks,
Lakshmi

narenderreddy · **Joined:** Tue Dec 12, 2006 7:52 am **Posts:** 20

hi
that session.isConnected() it takes the JDBC connection from the hibernate session it gives tru value

lakshmi_raga · **Joined:** Wed Feb 07, 2007 4:34 am **Posts:** 8

apparently, it intrigues me more,
meaning that, since the session.isConnected is returning true just after opening a new session from the sessionfactory and even before calling any persist, query apis or any trans.commits.

Then how does session creation become inexpensive?

belto.ntn · **Posted:** Tue Mar 13, 2007 5:47 am

lakshmi_raga wrote:

apparently, it intrigues me more,
meaning that, since the session.isConnected is returning true just after opening a new session from the sessionfactory and even before calling any persist, query apis or any trans.commits.

Then how does session creation become inexpensive?

hi;

Once u opened a session means it will renain opened until u r closing the
particular session u have to close the session if its is of no use further. u can use threadLocale design pattern. in wthe session will be closed automatically while u r commiting a transaction....

lakshmi_raga · **Joined:** Wed Feb 07, 2007 4:34 am **Posts:** 8

The answers i am receiving for this question are totally off the topic...

marias · **Posted:** Wed Mar 14, 2007 2:20 am

hi lakshmi, this session.isConnected() method returns true/false whether the session is opend() or closed() . but what u think is after calling
Transaction.commit() only we will get connection to the DB no thats correct i think so..as soon as u call sessionFactory.openSession() will get a DBconnection and a gets a session on it , after tx.commit() only ur all operations will hit DB once and makes the updates...

concluding that : sessionFactory().openSession() method only gets the connection not tx.commit().....see sessionFactory in api ok

marias · **Posted:** Wed Mar 14, 2007 2:23 am

hi lakshmi, this session.isConnected() method returns true/false whether the session is opend() or closed() . but what u think is after calling
Transaction.commit() only we will get connection to the DB no thats correct i think so..as soon as u call sessionFactory.openSession() will get a DBconnection and a gets a session on it , after tx.commit() only ur all operations will hit DB once and makes the updates...

concluding that : sessionFactory().openSession() method only gets the connection not tx.commit().....see sessionFactory in api ok

lakshmi_raga · **Joined:** Wed Feb 07, 2007 4:34 am **Posts:** 8

if session.isConnected() specifies whether the session is open or closed then what does session.isOpen() do?

ok, sessionFactory API says that openSession creates a new connection on it.
Suppose i have a getCurrentSession api defined to maintain session-per-request, and i close the session after each operation within the unit of work, then this session is saved within threadlocal space.
Do you mean that the session holds a connection for the entire duration?

And if I open 100 new sessions, according to the sessionFactory API,
each session will have a connection opened.
The author for this api is Gaving King.
But the book "Hibernate in Action" written by Gaving King says that unless it is necessary hibernate does not even require even a connection?

nathanmoon · **Posted:** Wed Mar 14, 2007 9:55 am

The documentation for the hibernate.connection.release_mode property may be helpful:

Quote:

Specify when Hibernate should release JDBC connections. By default, a JDBC connection is held until the session is explicitly closed or disconnected. For an application server JTA datasource, you should use after_statement to aggressively release connections after every JDBC call. For a non-JTA connection, it often makes sense to release the connection at the end of each transaction, by using after_transaction. auto will choose after_statement for the JTA and CMT transaction strategies and after_transaction for the JDBC transaction strategy.

eg. auto (default) | on_close | after_transaction | after_statement

Note that this setting only affects Sessions returned from SessionFactory.openSession. For Sessions obtained through SessionFactory.getCurrentSession, the CurrentSessionContext implementation configured for use controls the connection release mode for those Sessions. See Section 2.5, “Contextual Sessions”

My understanding is that if hibernate.connection.release_mode is set to auto, connections are obtained when the session is opened, and released when the session is closed. If it's set to after_transaction, I think it doesn't obtain a connection until session.beginTransaction (and then releases it after transaction.commit()).

Anyway, obtaining a connection should not be expensive because you should be using a connection pool. The connections have already been created, you are just checking it out of the pool (an inexpensive operation).