Sateful session bean passivation

Hi,
We know that stateful session beans are passivated depending on certain parameters, which is based completely on the Application server.
The passivation of the Stateful Bean is specified by Spec.
But i wonder what happens to the EJBObject itself. Every Stateful session bean will have its corresponding EJBObject, what happens to this EJBObject when the Bean is passivated. Does the EJBObject dies or does it stay alive all the time...
Thanks in advance,
Vijay.

Basically EJBObject is the request interceptor it does not store any client specific information, If the SFSB is passivated then the corresponding EJBOject will be associated with some other SFSB instance.

Similar Messages

A simple problem with sateful Session beans

Hi,
I have a really novice problem with stateful session bean in Java EE 5.
I have written a simple session bean which has a counter inside it and every time a client call this bean it must increment the count value and return it back.
I have also created a simple servlet to call this session bean.
Everything seemed fine I opened a firefox window and tried to load the page, the counter incremented from 1 to 3 for the 3 times that I reloaded the page then I opened an IE window (which I think is actually a new client) but the page counter started from 4 not 1 for the new client and it means that the new client has access to the old client session bean.
Am I missing anything here???
Isn�t it the way that a stateful session bean must react?
This is my stateful session bean source.
package test;
import javax.ejb.Stateful;
@Stateful
public class SecondSessionBean implements SecondSessionRemote
private int cnt;
/** Creates a new instance of SecondSessionBean */
public SecondSessionBean ()
cnt=1;
public int getCnt()
return cnt++;
And this is my simple client site servlet
package rezaServlets;
import java.io.*;
import java.net.*;
import javax.ejb.EJB;
import javax.servlet.*;
import javax.servlet.http.*;
import test.SecondSessionRemote;
public class main extends HttpServlet
@EJB
private SecondSessionRemote secondSessionBean;
protected void processRequest (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
response.setContentType ("text/html;charset=UTF-8");
PrintWriter out = response.getWriter ();
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet main</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Our count is " + Integer.toString (secondSessionBean.getCnt ()) + "</h1>");
out.println("</body>");
out.println("</html>");
out.close ();
protected void doGet (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
processRequest (request, response);
protected void doPost (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
processRequest (request, response);
}

You are injecting a reference to a stateful session bean to an instance variable in the servlet. This bean instance is shared by all servlet request, and that's why you are seeing this odd behavior.
You can use type-leve injection for the stateful bean, and then lookup the bean inside your request-processing method. You may also save this bean ref in HttpSession.
@EJB(name="ejb/foo", beanName="SecondBean", beanInterface="com.foo.foo.SecondBeanRemote")
public MyServlet extends HttpServlet {
ic.lookup("java:comp/env/ejb/foo");
}

How do i get back my stateful session bean after it has been passivated

hi ,
How do i get back my stateful session bean after it has been passivated by container.
i'm confused that is it possible or not .......give me answer
i've one stateful sessionbean which i'm accessing throgh my normal java client . now what i'm doing is when i first time call a method it is running ......then i'm shutting down the server jboss .......it is calling my ejbPassivate() method ... at this particular time client program doesn't do anything.....
now after i restart my server i'm again calling back that business method with that last object reference.......it gives me the exception given below.....
java.rmi.NoSuchObjectException: no such object in table
java.rmi.NoSuchObjectException: no such object in table
     at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Unknown Source)
     at sun.rmi.transport.StreamRemoteCall.executeCall(Unknown Source)
     at sun.rmi.server.UnicastRef.invoke(Unknown Source)
     at org.jboss.invocation.jrmp.server.JRMPInvoker_Stub.invoke(Unknown Source)
     at org.jboss.invocation.jrmp.interfaces.JRMPInvokerProxy.invoke(JRMPInvokerProxy.java:118)
     at org.jboss.invocation.InvokerInterceptor.invokeInvoker(InvokerInterceptor.java:227)
     at org.jboss.invocation.InvokerInterceptor.invoke(InvokerInterceptor.java:167)
     at org.jboss.proxy.TransactionInterceptor.invoke(TransactionInterceptor.java:46)
     at org.jboss.proxy.SecurityInterceptor.invoke(SecurityInterceptor.java:55)
     at org.jboss.proxy.ejb.StatefulSessionInterceptor.invoke(StatefulSessionInterceptor.java:106)
     at org.jboss.proxy.ClientContainer.invoke(ClientContainer.java:86)
     at $Proxy1.makeNewAcc(Unknown Source)
     at client.GanJavaClient.main(GanJavaClient.java:46)so pls tell me that is it possible to get back that session besn or not

Stateful session beans are not persisted across restart of the EJB server instance(s) hosting them. You can't treat a Session bean as one would an entity bean.
Chuck

Passivation of Connection Object in Stateful Session Bean

Hi all,
I am developing a Stateful session bean that has a Connection object as its instance variable. And this bean starts transaction that spans across multiple method calls and finally either commit or rollback.
BeanClass
UserTransaction utx;
Connection conn;
ejbCreate()
allocateconnection();
ejbRemove()
closeconnection();
ejbActivate()
allocateconnection();
ejbpassivate()
closeconnection();
StartTransaction()
utx = getusertransaction();
utx.begin();
Method1()
do something with database
Method2()
do something with database
CommitTransaction()
utx.commit();
For example, the typical usage of this bean would be:
bean.StartTransaction();
bean.Method1();
bean.Method2();
bean.CommitTransaction();
Here are my two questions:
1. General Question: In order for a Connection object to join a Transaction, Do I have to create the connection after the transaction has started?
2. If the answer to the above question is yes, then: I understand that when this bean get passivated, the UserTransaction instance object would be passivated. And since the connection object can't not be passivated, I have to recreate the connection object in ejbactivate() method, would newly created connection participate in the same Transaction that was being passivated and now activated?

>
Hi all,
I am developing a Stateful session bean that has a
Connection object as its instance variable. And this
bean starts transaction that spans across multiple
method calls and finally either commit or rollback.
BeanClass
UserTransaction utx;
Connection conn;
ejbCreate()
allocateconnection();
ejbRemove()
closeconnection();
ejbActivate()
allocateconnection();
ejbpassivate()
closeconnection();
StartTransaction()
utx = getusertransaction();
utx.begin();
Method1()
do something with database
Method2()
do something with database
CommitTransaction()
utx.commit();
For example, the typical usage of this bean would be:
bean.StartTransaction();
bean.Method1();
bean.Method2();
bean.CommitTransaction();
Here are my two questions:
1. General Question: In order for a Connection object
to join a Transaction, Do I have to create the
connection after the transaction has started?Strictly NO. In fact, the connection is obtained first and then can a transaction begin.
2. If the answer to the above question is yes, then: I
understand that when this bean get passivated, the
UserTransaction instance object would be passivated.
And since the connection object can't not be
passivated, I have to recreate the connection object
in ejbactivate() method, would newly created
connection participate in the same Transaction that
was being passivated and now activated?
The answer to first question being NO, your argument for question 2 does not hold true. According to the EJB specification, a stateful session bean can only be passivated between the transaction and not within a transaction. Your implementation for the stateful EJB is good to work.

Passivation of stateless session bean

For a stateful session bean, we mention the system directory in the server xml where Server stores the state of passivated stateful session bean instances.
Please can any one tell, if more than one beans are to be passivated how does it happen for one server instance?

The exact manner in which stateful session beans are passivated is considered an implementation detail. It is completely transparent to the developer.
Some implementations use a file-system as a stateful session bean store, while others use a database or memory replication.
If you're asking about specific configuration details I recommend consulting your vendor's documentation.
--ken

Stop passivation in stateful session bean

hi
How to stop the passivation in stateful session bean
Regards
Gajendran.G

>
Hi all,
I am developing a Stateful session bean that has a
Connection object as its instance variable. And this
bean starts transaction that spans across multiple
method calls and finally either commit or rollback.
BeanClass
UserTransaction utx;
Connection conn;
ejbCreate()
allocateconnection();
ejbRemove()
closeconnection();
ejbActivate()
allocateconnection();
ejbpassivate()
closeconnection();
StartTransaction()
utx = getusertransaction();
utx.begin();
Method1()
do something with database
Method2()
do something with database
CommitTransaction()
utx.commit();
For example, the typical usage of this bean would be:
bean.StartTransaction();
bean.Method1();
bean.Method2();
bean.CommitTransaction();
Here are my two questions:
1. General Question: In order for a Connection object
to join a Transaction, Do I have to create the
connection after the transaction has started?Strictly NO. In fact, the connection is obtained first and then can a transaction begin.
2. If the answer to the above question is yes, then: I
understand that when this bean get passivated, the
UserTransaction instance object would be passivated.
And since the connection object can't not be
passivated, I have to recreate the connection object
in ejbactivate() method, would newly created
connection participate in the same Transaction that
was being passivated and now activated?
The answer to first question being NO, your argument for question 2 does not hold true. According to the EJB specification, a stateful session bean can only be passivated between the transaction and not within a transaction. Your implementation for the stateful EJB is good to work.

Error While passivating Stateful session bean

I also have same problem when WL passivating. However, the exception throwing from
WL saying the "Ignoring exception raised while passivating".
My question is will that exception lead to failure of passivating and evenually
lead to memory leakage? I just thought that the memory is still in cache either
removed or passivated, as a result more and more memory will be used up as more
failure occurs.
Frank
Rob Woollen <[email protected]> wrote:
It looks like you have a reference to a DB Connection as a member
variable. This reference should be transient. You can re-acquire it
in
ejbActivate.
-- Rob
Hemant Arora wrote:
Hi
Can anybody please clarify the error that I'm getting while runningthe
stateful session bean with weblogic
I have instantiated 20 stateful session beans all using the DB connection
but if the connection is unaailable I'm making the beans to wait.
I'm not removeing the beans and again making the instance of 20 another
beans
The max beans in cache is 25.
Thanks
Hemant
This is the output at the console of the weblogic
ejbPassivate()
Tue Jul 17 20:58:00 GMT+05:30 2001:<I> <EJB JAR deployment
d:/weblogic/myserver/romanCount.jar> Ignoring exception raised while
passivating:
java.io.NotSerializableException:
weblogic.jdbc20.rmi.internal.ConnectionImpl
at
java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1148)
at
java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:366)
at
java.io.ObjectOutputStream.outputClassFields(ObjectOutputStream.java:1841)
at
java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:480)
at
java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1214)
at
java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:366)
at
java.io.ObjectOutputStream.outputClassFields(ObjectOutputStream.java:1841)
at
java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:480)
Coming Soon: Building J2EE Applications & BEA WebLogic Server
by Michael Girdley, Rob Woollen, and Sandra Emerson
http://learnweblogic.com

Stateful Session Beans are not passivated / serialized when cache idle time

Technology: Sun Application Server version 7.0.0_01; JDK 1.4.1; developed on Windows 2000; Tested on Sun Solaris.
Initial error on Sun Solaris:
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr: Exception in thread "service-j2ee-25" org.omg.CORBA.OBJ_ADAPTER: vmcid: SUN minor code: 1015 completed: No
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.POA.GenericPOAServerSC.preinvoke(GenericPOAServerSC.java:389)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.POA.ServantCachePOAClientSC.initServant(ServantCachePOAClientSC.java:112)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.POA.ServantCachePOAClientSC.setOrb(ServantCachePOAClientSC.java:95)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.iiop.CDRInputStream_1_0.createDelegate(CDRInputStream_1_0.java:760)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.iiop.CDRInputStream_1_0.internalIORToObject(CDRInputStream_1_0.java:750)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.iiop.CDRInputStream_1_0.read_Object(CDRInputStream_1_0.java:669)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.iiop.CDRInputStream_1_0.read_abstract_interface(CDRInputStream_1_0.java:890)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.iiop.CDRInputStream_1_0.read_abstract_interface(CDRInputStream_1_0.java:884)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.iiop.CDRInputStream.read_abstract_interface(CDRInputStream.java:307)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.se.internal.io.IIOPInputStream.readObjectDelegate(IIOPInputStream.java:228)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.se.internal.io.IIOPInputStream.readObjectOverride(IIOPInputStream.java:381)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at java.io.ObjectInputStream.readObject(ObjectInputStream.java:318)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.enterprise.iiop.IIOPHandleDelegate.getStub(IIOPHandleDelegate.java:58)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.enterprise.iiop.IIOPHandleDelegate.readEJBObject(IIOPHandleDelegate.java:38)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.ejb.portable.HandleImpl.readObject(HandleImpl.java:91)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.se.internal.io.IIOPInputStream.readObject(Native Method)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.se.internal.io.IIOPInputStream.invokeObjectReader(IIOPInputStream.java:1298)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.se.internal.io.IIOPInputStream.inputObject(IIOPInputStream.java:908)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.se.internal.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:261)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:247)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:981)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:287)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.sun.corba.ee.internal.javax.rmi.CORBA.Util.copyObject(Util.java:598)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at javax.rmi.CORBA.Util.copyObject(Util.java:314)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.telstra.nodeman.ejb._NodeMaint_Stub.getHandle(Unknown Source)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.telstra.nodeman.arch.NMAViewBeanProxy.checkBeans(NMAViewBeanProxy.java:631)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.telstra.nodeman.view.html.NMAStandardButton.handleRequest(NMAStandardButton.java:143)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.telstra.nodeman.arch.NMAViewBeanBase.handleRequest(NMAViewBeanBase.java:1573)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.iplanet.jato.view.ViewBeanBase.dispatchInvocation(ViewBeanBase.java:824)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.iplanet.jato.view.ViewBeanBase.invokeRequestHandlerInternal(ViewBeanBase.java:637)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.iplanet.jato.view.ViewBeanBase.invokeRequestHandler(ViewBeanBase.java:595)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.iplanet.jato.ApplicationServletBase.dispatchRequest(ApplicationServletBase.java:772)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.iplanet.jato.ApplicationServletBase.processRequest(ApplicationServletBase.java:446)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.iplanet.jato.ApplicationServletBase.doPost(ApplicationServletBase.java:324)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.telstra.nodeman.view.ViewServlet.doPost(ViewServlet.java:243)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at org.apache.catalina.core.StandardWrapperValve.invokeServletService(StandardWrapperValve.java:720)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at org.apache.catalina.core.StandardWrapperValve.access$000(StandardWrapperValve.java:118)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at org.apache.catalina.core.StandardWrapperValve$1.run(StandardWrapperValve.java:278)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at java.security.AccessController.doPrivileged(Native Method)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:274)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:505)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:212)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:505)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:203)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:505)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.iplanet.ias.web.connector.nsapi.NSAPIProcessor.process(NSAPIProcessor.java:158)
[10/Aug/2004:08:04:57] WARNING (17227): CORE3283: stderr:      at com.iplanet.ias.web.WebContainer.service(WebContainer.java:598)
The above error caused the server to use all available memory and required a reboot to proceed.
Subsequent testing against the Sun Appliucation Server 7 on Windows 2000 dev environment using the Sun Studio IDE for debugging and trace statements inserted in the code indicate that the Application Server is removing the Stateful Session Beans when they time out without an ejbPassivate event and without serializing the beans to the data-store. cache-idle-timeout-in-seconds set to 180 and removal-timeout-in-seconds set to 1800.
The server.log indicates that the beans are timing out:
[19/Aug/2004:18:15:10] WARNING ( 1664): [NRU-com.telstra.nodeman.ejb.AddressMaintBean]: IdleBeanCleanerTask finished after removing 2 idle beans
Trace statements inserted in ejbPassivate do not appear in the log.
It is my understanding that the above timeout should have caused an ejbPasssivate and serialization of the beans.
The beans have been validated using Sun Java Studio Enterprise 6 with 'EJB validate'.
My reading of the problem is that the beans are not being serialized and the error occurs when the application attempts to reference (getHandle) the bean after timeout.
Any suggestions would be appreciated.

Thanks Thorick.
I am using NRU caching. WL 7.0 SP2.
I have not defined idle-timeout-seconds in my weblogic-ejb-jar.xml. As I understand
the default value for this is 600secs. So the ejbs should be removed after this
time. Below is the
weblogic-ejb-jar.xml that I am using.
<!DOCTYPE weblogic-ejb-jar PUBLIC '-//BEA Systems, Inc.//DTD WebLogic 7.0.0 EJB//EN'
'http://www.bea.com/servers/wls700/dtd/weblogic-ejb-jar.dtd'>

<weblogic-ejb-jar>
<weblogic-enterprise-bean>
<ejb-name>Cart</ejb-name>
<stateful-session-descriptor>
<stateful-session-clustering>
<home-is-clusterable>true</home-is-clusterable>
<replication-type>InMemory</replication-type>
</stateful-session-clustering>
</stateful-session-descriptor>
<transaction-descriptor>
     <trans-timeout-seconds>
          60
     </trans-timeout-seconds>
</transaction-descriptor>
<jndi-name>CartHome</jndi-name>
</weblogic-enterprise-bean>
</weblogic-ejb-jar>
"thorick" <[email protected]> wrote:
>
The idle-timeout-seconds property controls the timeout/removal behavior.
which stateful session cache type are you using ? LRUCache or NRUCache

NON-transactional session bean access entity bean

We are currently profiling our product using Borland OptmizeIt tool, and we
found some interesting issues. Due to our design, we have many session beans which
are non transactional, and these session beans will access entity beans to do
the reading operations, such as getWeight, getRate, since it's read only, there
is no need to do transaction commit stuff which really takes time, this could
be seen through the profile. I know weblogic support readonly entity bean, but
it seems that it only has benefit on ejbLoad call, my test program shows that
weblogic still creates local transaction even I specified it as transaction not
supported, and Transaction.commit() will always be called in postInvoke(), from
the profile, we got that for a single method call, such as getRate(), 80% time
spent on postInvoke(), any suggestion on this? BTW, most of our entity beans are
using Exclusive lock, that's the reason that we use non-transactional session
bean to avoid dead lock problem.
Thanks

Slava,
Thanks for the link, actually I read it before, and following is what I extracted
it from the doc:
<weblogic-doc>
Do not set db-is-shared to "false" if you set the entity bean's concurrency
strategy to the "Database" option. If you do, WebLogic Server will ignore the
db-is-shared setting.
</weblogic-doc>
Thanks
"Slava Imeshev" <[email protected]> wrote:
Hi Jinsong,
You may want to read this to get more detailed explanation
on db-is-shared (cache-between-transactions for 7.0):
http://e-docs.bea.com/wls/docs61/ejb/EJB_environment.html#1127563
Let me know if you have any questions.
Regards,
Slava Imeshev
"Jinsong HU" <[email protected]> wrote in message
news:[email protected]...
Thanks.
But it's still not clear to me in db-is-shared setting, if I specifiedentity
lock as database lock, I assumed db-is-shared is useless, because foreach
new
transaction, entity bean will reload data anyway. Correct me if I amwrong.
Jinsong
"Slava Imeshev" <[email protected]> wrote:
Jinsong,
See my answers inline.
"Jinsong Hu" <[email protected]> wrote in message
news:[email protected]...
Hi Slava,
Thanks for your reply, actually, I agree with you, we need to
review
our db
schema and seperate business logic to avoid db lock. I can not say,guys,
we need
to change this and that, since it's a big application and developedsince
EJB1.0
spec, I think they are afraid to do such a big change.Total rewrite is the worst thing that can happen to an app. The
better aproach would be identifying the most critical piece and
make a surgery on it.
Following are questions in my mind:
(1) I think there should be many companies using weblogic serverto
develop
large enterprise applications, I am just wondering what's the maintransaction/lock
mechanism that is used? Transional session / database lock,
db-is-shared
entity
I can't say for the whole community, as for my experience the standard
usage patthern is session fasades calling Entity EJBs while having
Required TX attribute plus plain transacted JDBC calls for bulk
reads or inserts.
is the dominant one? It seems that if you speficy database lock,
the
db-is-shared
should be true, right?Basically it's not true. One will need db-is-shared only if thereare
changes
to the database done from outside of the app server.
(2) For RO bean, if I specify read-idle-timeout to 0, it shouldonly
load
once at the first use time, right?I assume read-timeout-seconds was meant. That's right, but if
an application constantly reads new RO data, RO beans will be
constantly dropped from cache and new ones will be loaded.
You may want to looks at server console to see if there's a lot
of passivation for RO beans.
(3) For clustering part, have anyone use it in real enterpriseapplication?
My concern, since database lock is the only way to choose, how aboutthe
affect
of ejbLoad to performance, since most transactions are short live,if high
volume
transactions are in processing, I am just scared to death about
the
ejbLoad overhead.
ejbLoad is a part of bean's lifecycle, how would you be scared ofit?
If ejbLoads take too much time, it could be a good idea to profile
used SQLs. Right index optimization can make huge difference.
Also you may want cosider using CMP beans to let weblogic
take care about load optimization.
(4) If using Optimization lock, all the ejbStore need to do
version
check
or timestamp check, right? How about this overhead?As for optimistic concurrency, it performs quite well as you can
use lighter isolation levels.
HTH,
Slava Imeshev
"Jinsong Hu" <[email protected]> wrote in message
news:[email protected]...
We are using Exclusive Lock for entity bean, because of we do
not
want
to
load
data in each new transaction. If we use Database lock, that means
we
dedicate
data access calls to database, if database deadlock happens,
it's
hard
to
detect,
while using Exclusive lock, we could detect this dead lock in
container
level.
The problem is, using Exclusive concurrency mode you serialize
access to data represented by the bean. This aproach has negative
effect on ablity of application to process concurrent requests.As
a
result the app may have performance problems under load.
Actually, at the beginnning, we did use database lock and usingtransactional
The fact that you had database deadlocking issues tells that
application logic / database schema may need some review.
Normally to avoid deadlocking it's good to group database
operations mixing in updattes and inserts into one place so
that db locking sequence is not spreaded in time. Moving to
forced serialized data access just hides design/implementation
problems.
session bean, but the database dead lock and frequent ejbLoad
really
kill
us,
so we decided to move to use Exclusive lock and to avoid dead
lock,
we
change
some session bean to non-transactional.Making session beans non-transactions makes container
creating short-living transactions for each call to entity bean
methods. It's a costly process and it puts additional load to
both container and database.
We could use ReadOnly lock for some entity beans, but since weblogicserver will
always create local transaction for entity bean, and we found
transaction
commit
is expensive, I am arguing why do we need create container leveltransaction for
read only bean.First, read-only beans still need to load data. Also, you may seeRO
beans
contanly loading data if db-is-shared set to true. Other reason
can
be
that
RO semantics is not applicable the data presented by RO bean (forinstance,
you have a reporting engine that constantly produces "RO" data,
while
application-consumer of that data retrieves only new data and neverasks
for "old" data). RO beans are good when there is a relatively stable
data
accessed repeatedly for read only access.
You may want to tell us more about your app, we may be of help.
Regards,
Slava Imeshev
I will post the performance data, let's see how costful
transaction.commit
is.
"Cameron Purdy" <[email protected]> wrote:
We are currently profiling our product using Borland
OptmizeIt
tool,
and we
found some interesting issues. Due to our design, we have
many
session
beans which
are non transactional, and these session beans will access
entity
beans
to
do
the reading operations, such as getWeight, getRate, since
it's
read
only,
there
is no need to do transaction commit stuff which really takes
time,
this
could
be seen through the profile. I know weblogic support readonly
entity
bean,
but
it seems that it only has benefit on ejbLoad call, my test
program
shows
that
weblogic still creates local transaction even I specified
it
as
transaction not
supported, and Transaction.commit() will always be called
in
postInvoke(),
from
the profile, we got that for a single method call, such as
getRate(),
80%
time
spent on postInvoke(), any suggestion on this? BTW, most of
our
entity
beans are
using Exclusive lock, that's the reason that we use
non-transactional
session
bean to avoid dead lock problem.I am worried that you have made some decisions based on an improper
understand of what WebLogic is doing.
First, you say "non transactional", but from your description
you
should
have those marked as tx REQUIRED to avoid multiple transactions
(since
non-transactional just means that the database operation becomesits
own
little transaction).
Second, you say you are using exclusive lock, which you shouldonly
use
if
you are absolutely sure that you need it, (and note that it
does
not
work in
a cluster).
Peace,
Cameron Purdy
Tangosol, Inc.
http://www.tangosol.com/coherence.jsp
Tangosol Coherence: Clustered Replicated Cache for Weblogic
"Jinsong Hu" <[email protected]> wrote in message
news:[email protected]...
>

In-memory-replace for stateful session bean

When I add "<replication-type>InMemory</replication-type>" at the
          weblogic-ejb-jar.xml file,
          the client can't call this stateful session bean and happen exception.
          If I delete "<replication-type>InMemory</replication-type>" at the
          weblogic-ejb-jar.xml, the client can call this ejb.
          How does the In-memory-replac set?
          Is there any limitations about using the In-memory-replace?
          The weblogic-ejb-jar.xml and the exception are list.
          The weblogic-ejb-jar.xml:
          <?xml version="1.0"?>
          <!DOCTYPE weblogic-ejb-jar PUBLIC '-//BEA Systems, Inc.//DTD WebLogic 6.0.0
          EJB//EN' 'http://www.bea.com/servers/wls600/dtd/weblogic-ejb-jar.dtd'>
          <weblogic-ejb-jar>
          <weblogic-enterprise-bean>
          <ejb-name>test_stateful</ejb-name>
          <stateful-session-descriptor>
          <stateful-session-clustering>
          <home-is-clusterable>True</home-is-clusterable>
          <home-load-algorithm>round-robin</home-load-algorithm>
          <home-call-router-class-name>beanRouter</home-call-router-class-name>
          <replication-type>InMemory</replication-type>
          </stateful-session-clustering>
          </stateful-session-descriptor>
          <jndi-name>test_stateful</jndi-name>
          </weblogic-enterprise-bean>
          </weblogic-ejb-jar>
          The exception:
          java.rmi.RemoteException: EJB Exception: ; nested exception is:
          java.lang.ClassCastException:
          weblogic.rmi.internal.BasicRequestDispatcher
          java.lang.ClassCastException: weblogic.rmi.internal.BasicRequestDispatcher
          <<no stack trace available>>


This is a Work as designed in my opinion
with NRU ,the container work with an eager remove algorithm, this as stated need pressure at the cache to push the container to remove the beans from the cache ,hence there will no passivation unless the max-beans-in-cache is reached, hence you can try reducing the max-beans-in-cache and see how the caching behaves , if It does not help ,chnage the Algorithm of caching or open a Service Request for us , we can look at this closely
Regards
Anis

Bean passivation not completed

Environment: WLS 6.1 SP2 on NT
Hi,
I am loading 50 entities (EJB 2.0 BMP) and playing with WLS configuration
to force the container to passivate them.
I set max-beans-in-cache to 100, idle-timeout-seconds to 10 seconds
and concurrency-strategy to Database.
In addtion, I set the passivation-strategy to transaction to make sure
the container will passivate the bean after every transaction.
I ran my test to list the details of my 50 objects. 50 local entities
are indeed created, but none are passivated.
I would have expected the container to passivate them after 10 seconds
given my idle-timeout-seconds value. My passivation-strategy being set
to transaction, I would have expected the container to passivate them
straight away anyway.
If I change max-beans-in-cache to 30, the container passivates 20 entities
(activation count 50, passivation count 20, idle beans count 20, beans in
use count 30)
If I run it again the values change as expected to
activation count 70 (50+20), passivation count 40 (20+20), idle beans count
20, beans in use count 30.
My questions are:
Is idle-timeout-seconds working ?
Is passivation-strategy working ?
Is the console displaying the right information?
Could someone tell me what is the best practice for passivation policy?
It is not normal that my 50 entities will sit there for the whole day even
if there are not used.
They should be passivated shouldn't they?
Cheers
Arnaud

Arnaud wrote:
Environment: WLS 6.1 SP2 on NT
Hi,
I am loading 50 entities (EJB 2.0 BMP) and playing with WLS configuration
to force the container to passivate them.
I set max-beans-in-cache to 100, idle-timeout-seconds to 10 seconds
and concurrency-strategy to Database.
In addtion, I set the passivation-strategy to transaction to make sure
the container will passivate the bean after every transaction.
Passivation-strategy was deprecated in 6.0. It doesn't do anything in
6.0 or later. Actually it never really worked correctly even in 5.1.
idle-timeout-seconds is not used for entity bean passivation. That
parameter is only used for session beans.
I ran my test to list the details of my 50 objects. 50 local entities
are indeed created, but none are passivated.
I would have expected the container to passivate them after 10 seconds
given my idle-timeout-seconds value. My passivation-strategy being set
to transaction, I would have expected the container to passivate them
straight away anyway.
If I change max-beans-in-cache to 30, the container passivates 20 entities
(activation count 50, passivation count 20, idle beans count 20, beans in
use count 30)Right
If I run it again the values change as expected to
activation count 70 (50+20), passivation count 40 (20+20), idle beans count
20, beans in use count 30.
My questions are:
Is idle-timeout-seconds working ?
Is passivation-strategy working ?See above
Is the console displaying the right information?
Could someone tell me what is the best practice for passivation policy?
It is not normal that my 50 entities will sit there for the whole day even
if there are not used.
They should be passivated shouldn't they?
It depends on your usage. The better solution is in 7.0 where you can
configure application caches that will hold many different types of
EJBs. They're better able to handle mixed EJB loads.
-- Rob
Cheers
Arnaud

HttpSession vs. Stateful Session Bean ---- when State Session is large

I hope most of the people come across with this issue where to put the state
for the internet/intranet based applications when they are using
servlet/jsps calling session beans. Weblogic 4.5.1 does support httpsession
in-memory replication for the servlets but the stateful session beans are
not replicated in clustered environment. Plus with stateful bean u get
activation/passivation overhead too. So one tempts to use stateless session
beans and store state in httpsession?
Then what is the upper limit for the session state one can put in
HttpSession with the weblogic? Is there any way to configure it?
One way to overcome the httpsession size limitation is to use database for
storing state and just store some unique Ids for the session info in
httpSession. But then there will be overhead for database connection?(jdbc
connection pool can provide some help here). So what is the recommended way
for doing this provided few thousand concurrent clients with session size
say exceeding 4kb per client?
Thanks
Usmani

There are no special setting in sun-ejb-jar.xml regarding cache settings. The default settings from server.xml are used:
    <jdbc-connection-pool steady-pool-size="8" max-pool-size="32" max-wait-time-in-millis="60000" pool-resize-quantity="2" idle-timeout-in-seconds="300" is-isolation-level-guaranteed="false" is-connection-validation-required="false" connection-validation-method="auto-commit" fail-all-connections="false" datasource-classname="oracle.jdbc.pool.OracleDataSource" name="ebs">
      <property value="jdbc:oracle:thin:@myebsdbsserver:1521:ebsdevdb" name="url"/>
      <property value="ebs" name="user"/>
      <property value="ebs" name="password"/>
    </jdbc-connection-pool>
<ejb-container steady-pool-size="32" pool-resize-quantity="16" max-pool-size="64" cache-resize-quantity="32" max-cache-size="512" pool-idle-timeout-in-seconds="600" cache-idle-timeout-in-seconds="600" removal-timeout-in-seconds="5400" victim-selection-policy="nru" commit-option="B" monitoring-enabled="true">
     </ejb-container>The Session Bean uses Container Managed Transaction. Is it possible in this case, that the bean isn't 'idle enough' in order to set into passivated?

Stateful Session Bean with BMT: JDBCpmf or EEpmf?

Quote:
For the record: when using BMT as David described, you should use a JDBCPersistenceManagerFactory
instead of an EEPersistenceManagerFactory. EEPersistenceManagerFactory is only appropriate when
transaction synchronization is desired.
-Patrick
Hi Patrick,
I wanted to follow up on this. In the case of Kodo, the JDBCpmf does not turn on the
UserTransaction in a managed environment, while the EEpmf does. My question: isn't is necessary to
turn on the UserTransaction in a stateful session bean with BMT? If this doesn't happen, isn't
there a danger, if the bean allows transactions to span business method invocations, that the
container will passivate the bean while a transaction is active? Since the PM can't be saved during
passivation, the tx would be interrupted by passivation -- something that would not happen if the
container were aware that a tx was active.
David Ezzio

David,
My interpretation of your initial post was that you were using fully
unmanaged transactions in your bean. That is, that you were not using the
UserTransaction, but were just using the javax.jdo.Transaction for
transactional data store access.
In the situation I just described, using the EEPMF would result in changes
to the UserTransaction. If your goal was to manage the UserTransaction in
the bean, then yes, you'd still want to use the EEPMF.
-Patrick
On 7/25/02 7:17 PM, "David Ezzio" <[email protected]> wrote:
Quote:
For the record: when using BMT as David described, you should use a
JDBCPersistenceManagerFactory
instead of an EEPersistenceManagerFactory. EEPersistenceManagerFactory is only
appropriate when
transaction synchronization is desired.
-Patrick
Hi Patrick,
I wanted to follow up on this. In the case of Kodo, the JDBCpmf does not turn
on the
UserTransaction in a managed environment, while the EEpmf does. My question:
isn't is necessary to
turn on the UserTransaction in a stateful session bean with BMT? If this
doesn't happen, isn't
there a danger, if the bean allows transactions to span business method
invocations, that the
container will passivate the bean while a transaction is active? Since the PM
can't be saved during
passivation, the tx would be interrupted by passivation -- something that
would not happen if the
container were aware that a tx was active.
David Ezzio--
Patrick Linskey [email protected]
SolarMetric Inc. http://www.solarmetric.com

Stateful session bean time out

How to specify a stateful session beans's time out value?
Thanks,
Jack

Bear in mind that setting a timeout for a stateful session bean will
typically have no more effect than setting a maximum number of beans. As
with garbage collection in Java, beans become eligible for passivation or
removal when their timeout expires and there are more beans than the
maximum, but they will only be removed or passivated when the server runs
low on memory.
Dave
"jack" <[email protected]> wrote in message
news:[email protected]..
>
How to specify a stateful session beans's time out value?
Thanks,
Jack

Ejbpassivate and ejbactivate methods in session beans?

I have read in most of the sites that stateful session beans are not pooled, then when ejbpassivate and ejbactivate methods are used?
As per my understanding ,when SFSB are pooled and all SFSB are engaged in servicing then say some request comes. Then container tries to passivate the LRU SFSB anf make it available for new request. But i think it is required in case of pooling only.
If SFSB are not pooled is there any need of passivate/activate methods?

It's not the SF EJB itself that is being used for multiple clients, it's the resources that are being used by the EJB that can be freed up for use by other objects while the EJB is passivated.

Sateful session bean passivation

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