Rad-only Entity beans are replicated?

Hi. I have just read the document "Failover and Replication in a cluster": http://edocs.bea.com/wls/docs81/cluster/failover.html#1008850
I have no clear if read-only entity beans are replicated?
I understand that replica-aware stub does not mean that stub objects are replicated in all the servers of the cluster. This seems to be only for statefull session beans.
Thx.

Hi,
we use read only entity beans. It is beneficial if have findByPrimaryKey finders. but we also have finders on non primary key coloumn also. is there a way to cache such local references returned by such non primary key finders also.

Similar Messages

Load balancing not happending but fail over is for Read only Entity beans

          The following are the configuration.
          Two NT servers with WL5.1 sp9 having only EJBs(Read only entity beans)
          One Client with WL5.1 sp9 having servlet/java application as
          EJB client.
          I am trying to make a call like findbyprimarykey in one of the
          entity bean. I could see the request is being directed only to the one of the
          server always. When I bring that server, fail over is happening to the other server.
          Here are the settings I have in the ejb-jar.xml :
                    <entity>
                         <ejb-name>device.StartHome</ejb-name>
                         <home>com.wl.api.device.StartHome</home>
                         <remote>com.wl.api.device.StartRemote</remote>
                         <ejb-class>com.wl.server.device.StartImpl</ejb-class>
                         <persistence-type>Bean</persistence-type>
                         <prim-key-class>java.lang.Long</prim-key-class>
                         <reentrant>False</reentrant>
                         <resource-ref>
                              <res-ref-name>jdbc/wlPool</res-ref-name>
                              <res-type>javax.sql.DataSource</res-type>
                              <res-auth>Container</res-auth>
                         </resource-ref>
                    </entity>
          Here are the settings I have in the weblogic-ejb-jar.xml.
          <weblogic-enterprise-bean>
                    <ejb-name>device.StartHome</ejb-name>
                    <caching-descriptor>
                         <max-beans-in-cache>50</max-beans-in-cache>
                         <cache-strategy>Read-Only</cache-strategy>
                         <read-timeout-seconds>900</read-timeout-seconds>
                    </caching-descriptor>
                    <reference-descriptor>
                         <resource-description>
                              <res-ref-name>jdbc/wlPool</res-ref-name>
                              <jndi-name>weblogic.jdbc.pool.wlPool</jndi-name>
                         </resource-description>
                    </reference-descriptor>
                    <enable-call-by-reference>False</enable-call-by-reference>
                    <jndi-name>device.StartHome</jndi-name>
               </weblogic-enterprise-bean>
          Am I doin any mistake in this?
          Any one's help is appreciated.
          Thanks
          Suresh


we are using 5.1
          "Gene Chuang" <[email protected]> wrote in message
          news:[email protected]...
          > Colocation optimization occurs if your client resides in the same
          container (and also in the same
          > EAR for 6.0) as your ejbs.
          >
          > Gene
          >
          > "Suresh" <[email protected]> wrote in message
          news:[email protected]...
          > > Ok....the ejb-call-by-reference set to true is making the call to one
          server
          > > only. i am not sure why it is. I removed the property name and it
          works.
          > > Also I have one question, in our prduct environment, when i cache the
          ejb
          > > home it is not doing the load balancing. can any one help me for that.
          > > thanks
          > >
          > > Mike,
          > > From the sample pgm I sent, even from single client calls get load
          > > balanced.
          > >
          > > Suresh
          > >
          > >
          > > "Gene Chuang" <[email protected]> wrote in message
          > > news:[email protected]...
          > > > In WL, LoadBalancing will ONLY WORK if you reuse your EJBHome! Take
          your
          > > StartEndPointHome lookup
          > > > out of your for loop and see if this fixes your problem.
          > > >
          > > > I've seen this discussion in ejb-interest, and some other vendor
          (Borland,
          > > I believe it is), brings
          > > > up an interesting point: Clustering and LoadBalance is not in the
          J2EE
          > > specs, hence implementation
          > > > is totally up to the vendor. Weblogic loadbalances from the remote
          > > interfaces (EJBObject, EJBHome,
          > > > etc..), while Borland loadbalances from JNDI Context lookup.
          > > >
          > > > Let me suggest a third implmentation: loadbalance from BOTH Context
          > > lookup as well as stub method
          > > > invocation! Or create a smart replica-aware list manager which
          persists
          > > on the client thread
          > > > (ThreadLocal) and is aware of lookup/evocation history. Hence if I do
          the
          > > following in a client
          > > > hitting a 3 node cluster, I'll still get perfect round-robining
          regardless
          > > of what I do on the
          > > > client side:
          > > >
          > > > InitialContext ctxt = new InitialContext();
          > > > EJBHome myHome = ctxt.lookup(MY_BEAN);
          > > > myHome.findByPrimaryKey(pk); <== hits Node #1
          > > > myHome = ctxt.lookup(MY_BEAN);
          > > > myHome.findByPrimaryKey(pk); <== hits Node #2
          > > > myHome.findByPrimaryKey(pk); <== hits Node #3
          > > > myHome = ctxt.lookup(MY_BEAN);
          > > > myHome.findByPrimaryKey(pk); <== hits Node #1
          > > > ...
          > > >
          > > >
          > > > Gene
          > > >
          > > > "Suresh" <[email protected]> wrote in message
          > > news:[email protected]...
          > > > > Mike ,
          > > > >
          > > > > Do you have any reasons for the total number of machines to be 10.
          > > > >
          > > > > I tried with 7 machines.
          > > > >
          > > > >
          > > > > Here is my sample client java application running individual in the
          > > seven
          > > > > machines.
          > > > >
          > > > > StartEndPointHome =
          > > > > (StartEndPointHome)ctx.lookup("dev.StartEndPointHome");
          > > > > for(;;)
          > > > > {
          > > > > // logMsg(" --in loop "+currentTime);
          > > > > if (currentTime > nextRefereshTime)
          > > > > {
          > > > > logMsg("****- going to call");
          > > > > currentTime=getSystemTime();
          > > > > nextRefereshTime=currentTime+timeInterval;
          > > > > StartEndPointHome =
          > > > > (StartEndPointHome)ctx.lookup("dev.StartEndPointHome");
          > > > > long rndno=(long)(Math.random()*10)+range;
          > > > > logMsg(" going to call remotestub"+rndno);
          > > > > retVal =
          > > > >
          > >
          ((StartEndPointHome)getStartHome()).findByNumber("pe"+rndno+"_mportal_dsk36.
          > > > > mportal.com");
          > > > >
          > > > > logMsg("**++- called stub");
          > > > > }
          > > > >
          > > > >
          > > > >
          > > > > The range value is different for each of the machines in the
          cluster.
          > > > >
          > > > > If the first request starts at srv1, all request starts hitting the
          same
          > > > > server.
          > > > > If the first request starts at srv2, all request starts hitting the
          same
          > > > > server.
          > > > >
          > > > > I have the following for the url , user and pwd values for the
          context
          > > .
          > > > >
          > > > > public static String url="t3://10.11.12.14,10.11.12.117:8000";
          > > > > public static String user="guest";
          > > > > public static String password="guest";
          > > > >
          > > > >
          > > > >
          > > > > It would be great if you could help me.
          > > > >
          > > > > Thanks
          > > > > suresh
          > > > >
          > > > >
          > > > > "Mike Reiche" <[email protected]> wrote in message
          > > > > news:[email protected]...
          > > > > >
          > > > > > If you have only one client don't be surprised if you only hit one
          > > server.
          > > > > Try
          > > > > > running ten different clients and see if the hit the same server.
          > > > > >
          > > > > > Mike
          > > > > >
          > > > > >
          > > > > > "suresh" <[email protected]> wrote:
          > > > > > >
          > > > > > >The following are the configuration.
          > > > > > >
          > > > > > > Two NT servers with WL5.1 sp9 having only EJBs(Read only entity
          > > beans)
          > > > > > >
          > > > > > > One Client with WL5.1 sp9 having servlet/java application as
          > > > > > > EJB client.
          > > > > > >
          > > > > > >
          > > > > > >I am trying to make a call like findbyprimarykey in one of the
          > > > > > >entity bean. I could see the request is being directed only to
          the
          > > one
          > > > > > >of the
          > > > > > >server always. When I bring that server, fail over is happening
          to
          > > the
          > > > > > >other server.
          > > > > > >
          > > > > > >
          > > > > > >Here are the settings I have in the ejb-jar.xml :
          > > > > > > <entity>
          > > > > > > <ejb-name>device.StartHome</ejb-name>
          > > > > > > <home>com.wl.api.device.StartHome</home>
          > > > > > > <remote>com.wl.api.device.StartRemote</remote>
          > > > > > > <ejb-class>com.wl.server.device.StartImpl</ejb-class>
          > > > > > > <persistence-type>Bean</persistence-type>
          > > > > > > <prim-key-class>java.lang.Long</prim-key-class>
          > > > > > > <reentrant>False</reentrant>
          > > > > > > <resource-ref>
          > > > > > > <res-ref-name>jdbc/wlPool</res-ref-name>
          > > > > > > <res-type>javax.sql.DataSource</res-type>
          > > > > > > <res-auth>Container</res-auth>
          > > > > > > </resource-ref>
          > > > > > > </entity>
          > > > > > >
          > > > > > >
          > > > > > >Here are the settings I have in the weblogic-ejb-jar.xml.
          > > > > > >
          > > > > > ><weblogic-enterprise-bean>
          > > > > > > <ejb-name>device.StartHome</ejb-name>
          > > > > > >
          > > > > > > <caching-descriptor>
          > > > > > > <max-beans-in-cache>50</max-beans-in-cache>
          > > > > > > <cache-strategy>Read-Only</cache-strategy>
          > > > > > > <read-timeout-seconds>900</read-timeout-seconds>
          > > > > > > </caching-descriptor>
          > > > > > >
          > > > > > > <reference-descriptor>
          > > > > > > <resource-description>
          > > > > > > <res-ref-name>jdbc/wlPool</res-ref-name>
          > > > > > > <jndi-name>weblogic.jdbc.pool.wlPool</jndi-name>
          > > > > > > </resource-description>
          > > > > > > </reference-descriptor>
          > > > > > > <enable-call-by-reference>False</enable-call-by-reference>
          > > > > > > <jndi-name>device.StartHome</jndi-name>
          > > > > > > </weblogic-enterprise-bean>
          > > > > > >
          > > > > > >
          > > > > > >Am I doin any mistake in this?
          > > > > > >
          > > > > > >Any one's help is appreciated.
          > > > > > >Thanks
          > > > > > >Suresh
          > > > > >
          > > > >
          > > > >
          > > >
          > > >
          > >
          > >
          >
          >

Problem with Read-Only Entity Bean

Hi All,
I have an Read-Only BMP that just read data from 20 tables and stores them in a Collection. In a 'Read-Only' Entity bean, the ejbLoad() is supposed to called periodically as defined by 'read-timeout-seconds' parameter in 'weblogic-ejb-jar.xml'. But this doesn't happen. Every time I invoke the EJB, ejbCreate() and ejbLoad() get called. Any suggestions will be highly appreciated.
Here is the content of my 'weblogic-ejb-jar.xml' file.
<?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>beanManaged</ejb-name>
     <entity-descriptor>
          <entity-cache>
               <max-beans-in-cache>1</max-beans-in-cache>
               <read-timeout-seconds>5</read-timeout-seconds>
               <concurrency-strategy>ReadOnly</concurrency-strategy>
          </entity-cache>
     </entity-descriptor>
<jndi-name>beanManaged</jndi-name>
</weblogic-enterprise-bean>
</weblogic-ejb-jar>
Thanks,
Prem

Yes, it calls ejbLoad() at intervals defined by read-timeout-seconds, but only when bean
is requested by the client, and the cached copy is old. If bean just sits in the cache
unused no ejbLoad()'s will be called.
Prem Raghupathy <[email protected]> wrote:
The weblogic document on 'Setting Entity EJBs to Read-Only' says "WebLogic Server
never calls ejbStore() for a read-only entity EJB. ejbLoad() is called initially
when the EJB is created; afterwards, WebLogic Server calls ejbLoad() only at intervals
defined by the read-timeout-seconds deployment parameter.". Here is the link to
the document
http://edocs.bea.com/wls/docs61/ejb/EJB_environment.html#1074846
Dimitri Rakitine <[email protected]> wrote:
WebLogic doesn't reload Read-Only entity beans periodically. It loads
bean instance only when client requests it, and instance is not in the
cache, or cached instance is older than read-timeout-seconds.
Prem Raghupathy <[email protected]> wrote:
This is a multi-part message in MIME format.
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Content-Type: text/plain
Content-Transfer-Encoding: 7bit
Rajesh,
Thanks for your reply. I’m using WL6.1 sp1. When I log the methodcalls,
this is what I see on the server console.
SetEntityContext()
ejbCreate()
ejbPostCreate()
ejbLoad()
As you see, the ejbLoad() doesn’t get called every 5 sec, eventhough I
set the ‘read-timeout-seconds=5’ in the weblogic-ejb-jar.xml,
Do you have a working example for Read-Only BMP on WL6.1? The examplesdirectory
in weblogic 6.1 doesn’t have one.
Also find attached all the files. Any suggestions will be highly appreciated.
Thanks,
Prem.
Rajesh Mirchandani <[email protected]> wrote:
What version of the Server and Service pack are you using? Turn on
JDBC
logging and see if every ejbLoad() hits the DB.
prem wrote:
Hi All,
I have an Read-Only BMP that just read data from 20 tables and storesthem in a Collection. In a 'Read-Only' Entity bean, the ejbLoad() is
supposed to called periodically as defined by 'read-timeout-seconds'
parameter in 'weblogic-ejb-jar.xml'. But this doesn't happen. Every
time I invoke the EJB, ejbCreate() and ejbLoad() get called. Any suggestions
will be highly appreciated.
Here is the content of my 'weblogic-ejb-jar.xml' file.
<?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>beanManaged</ejb-name>
<entity-descriptor>
<entity-cache>
<max-beans-in-cache>1</max-beans-in-cache>
<read-timeout-seconds>5</read-timeout-seconds>
<concurrency-strategy>ReadOnly</concurrency-strategy>
</entity-cache>
</entity-descriptor>
<jndi-name>beanManaged</jndi-name>
</weblogic-enterprise-bean>
</weblogic-ejb-jar>
Thanks,
Prem--
Rajesh Mirchandani
Developer Relations Engineer
BEA Support
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---=_newsgroups3c21148f----
Dimitri
Dimitri

Read Only entity beans and Finders

Hi,
We are using Read Only entity beans with WLS 7.0 SP1 for some entities that represent Reference Data that will never change. What I would like to know is whether WLS needs to hit the database when a finder on these beans is run or does WLS cache the results of the Finder also?
Thanks.
Santosh

Hi,
we use read only entity beans. It is beneficial if have findByPrimaryKey finders. but we also have finders on non primary key coloumn also. is there a way to cache such local references returned by such non primary key finders also.

Are ENtity Beans are deprecated in 3.0 version

Hi the below line is from the book "Mastering EJB 3.0 "
Note that Entity beans havent been enhanced in ejb3.0 , since there have been no changes made to them .
What does this mean actually ?
Does it mean ENtity Beans are deprecated in 3.0 version ?

>
Hi kiran7882,
Note that Entity beans havent been enhanced in ejb3.0 , since there have been no changes made to them .Entity beans are specific to persistence managers. EJB's are only modules which can use them like any other objects.
Does it mean ENtity Beans are deprecated in 3.0 version ?No.

Read Only Entity Bean will not cache

I'm using the Sun Java Application Server version 8.2. I've created a read only entity bean with a 900 second refresh. This bean has a findAll() method that I've created. The table it is reading from has only 22 rows of data that doesn't change (well, maybe 2 or 3 times a year).
As stated I've set the read-only property to true and the refresh to 900 seconds. I've also set the caching settings, which I guess i don't really need to mess with from the defaults.
I do not seem to be achieving any caching at all. My check for this is very simple. I simply load a drop down in the client application with these 22 values. After the intial load I add another row in the database. The newley added row always shows up in the drop down in real time. If i'm caching correctly I shouldn't see this value until the refresh time of 900 seconds. Is there something I am missing? I'm using NetBeans 5.0 to set the values of the entity beans and such.
Thanks for the help!
ryan

Hi Ryan,
The 8.2 read-only bean implementation still executes non-findByPrimaryKey queries within the database.
If your application calls findByPrimaryKey or accesses a business method on one of the
read-only beans returned from a query, that will not result in a database access (unless a refresh
period boundary is crossed).
We have added the additional optimization of caching specific result sets of non-findByPrimaryKey
read-only bean finders in the latest development version of Glassfish (V2).
https://glassfish.dev.java.net/public/downloadsindex.html#Official_supported_builds
It will also be available in our Application Server release 9.1. There are no plans to backport this
optimization to the 8.2 codebase.
--ken

Primary Key for Read Only Entity Beans In EJB 3.0

Hi,
I have checked the spec for ejb 3.0 which mentions that, there is no common standard for the vendor to implement the Read only Entity Beans.
My question over here is how it is implemented in OC4J??
Do we need to specify a primary key attribute in the read-only entity bean?
w.r.t BC4J(ADF) i remember, we used to create a read-only View Object with out specifying a primary key.
Just want to check is that the way it works in EJB 3.0 (Implemented by OC4J).
Thanks for your help in advance.
Shiva

Hi,
Try using the JBoss embedded container:
http://docs.codehaus.org/display/MAVENUSER/How+to+use+the+JBoss+Embedded+EJB3+Container+for+Unit+testing
/klejs

Are EJB ( entity beans) are cached ?

Are EJB ( entity beans) are cached ?
I have a doubt here . As per my understanding , the entity beans are cached from the database. In that case , If I delete a row in the database by an external application ( say using TOAD tool) , how the Entity bean will be updated / reloaded ? Entity bean will be out of sync then .
Application server : weblogic/webspehere .

>
You can use the refresh method of the EntityManager interface to read new values from the database (if you expect it to be out of sync), and use locks to prevent others from changing your data while the application is performing actions in a transaction.Did you mean I have to write code for this ? can't be made it automatic refresh by the container ? Is there any settings I can configure so that container can do it by itself proactively ?
Also, using locks ...is this a container settings or I need to configure myself in ejb-jar.xml ? Could you please shed some light here ?

Re: Read Only Entity Bean

I am trying to convert an entity bean into a read only bean .
I am not sure how it works ? I read the documentation and it said that I had to
set
the following parameters
cache-strategy>Read-Write</cache-strategy>
read-timeout-seconds>100</read-timeout-seconds>
If I set the time out time to 100 seconds will the container call the ejbLoad
method
to reload the bean after every 100 seconds or only when the a request is made
on the
bean
Thanks a lot in advance for your answers.

Kevin,
"Kevin" <[email protected]> wrote in message
news:3ec25923$[email protected]..
I am trying to convert an entity bean into a read only bean .
I am not sure how it works ? I read the documentation and it said that Ihad to
set
the following parameters
cache-strategy>Read-Write</cache-strategy>
read-timeout-seconds>100</read-timeout-seconds>
If I set the time out time to 100 seconds will the container call theejbLoad
method
to reload the bean after every 100 seconds or only when the a request ismade
on the
bean
Thanks a lot in advance for your answers.read-timeout-seconds make sense only for Read-Only
cache strategy and defines cache element expiration time.
For Read-Write strategy data will be loaded from the database
in with every new transaction (if db-is-shared set to true).
Hope this helps.
Regards,
Slava Imeshev

Read only entity beans

Is there any way to mark an entity bean as read only? I'm using glassfish V2.

JPA does not define a read-only concept, but TopLink Essentials (glassfish v2 persistence) does. You can use a DescriptorCustomizer to set your TopLink Descriptor to be read-only (descriptor.setReadOnly()).
TopLink 11g, and EclipseLink (Glassfish v3) also provider a query hint for returning read-only objects at the query level ("eclipselink.return-shared").
-- James : EclipseLink

Help reg. read only CMP bean in the examples!!

Hi,
I have been working with examples of EJB in WLS 6.1
I used the Access database with CMP.
The basic entity beans, both CMP and BMP worked well.
However when I tried the read-only Stock Bean and write StockWriter Beans... I received the following error... I am not sure what does it say...
==============================================
Beginning readMostly.Client...
Creating a StockWriter for BEAS
There was an exception while creating and using the Beans.
This indicates that there was a problem communicating with the server: java.rmi.RemoteException: EJB Exception:; nested exception is:
java.sql.SQLException: [Microsoft][ODBC Microsoft Access Driver]Optional feature not implemented
Start server side stack trace:
java.rmi.RemoteException: EJB Exception:; nested exception is:
java.sql.SQLException: [Microsoft][ODBC Microsoft Access Driver]Optional feature not implemented
java.sql.SQLException: [Microsoft][ODBC Microsoft Access Driver]Optional feature not implemented
at sun.jdbc.odbc.JdbcOdbc.createSQLException(JdbcOdbc.java:6026)
at sun.jdbc.odbc.JdbcOdbc.standardError(JdbcOdbc.java:6183)
at sun.jdbc.odbc.JdbcOdbc.SQLBindInParameterFloat(JdbcOdbc.java:852)
at sun.jdbc.odbc.JdbcOdbcPreparedStatement.setLong(JdbcOdbcPreparedStatement.java:575)
at weblogic.jdbc.pool.Statement.setLong(Statement.java:369)
at weblogic.jdbc.rmi.internal.PreparedStatementImpl.setLong(PreparedStatementImpl.java:114)
at weblogic.jdbc.rmi.SerialPreparedStatement.setLong(SerialPreparedStatement.java:147)
at ejb.readMostly.StockWriterBean_u4qwd5__WebLogic_CMP_RDBMS.__WL_create(StockWriterBean_u4qwd5__WebLogic_CMP_RDBMS.java:589)
at ejb.readMostly.StockWriterBean_u4qwd5__WebLogic_CMP_RDBMS.ejbCreate(StockWriterBean_u4qwd5__WebLogic_CMP_RDBMS.java:518)
at java.lang.reflect.Method.invoke(Native Method)
at weblogic.ejb20.manager.DBManager.create(DBManager.java:519)
at weblogic.ejb20.manager.DBManager.remoteCreate(DBManager.java:489)
at weblogic.ejb20.internal.EntityEJBHome.create(EntityEJBHome.java:190)
at ejb.readMostly.StockWriterBean_u4qwd5_HomeImpl.create(StockWriterBean_u4qwd5_HomeImpl.java:78)
at ejb.readMostly.StockWriterBean_u4qwd5_HomeImpl_WLSkel.invoke(Unknown Source)
at weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:305)
at weblogic.rmi.cluster.ReplicaAwareServerRef.invoke(ReplicaAwareServerRef.java:93)
at weblogic.rmi.internal.BasicServerRef.handleRequest(BasicServerRef.java:274)
at weblogic.rmi.internal.BasicExecuteRequest.execute(BasicExecuteRequest.java:22)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:139)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
End server side stack trace
; nested exception is:
java.sql.SQLException: [Microsoft][ODBC Microsoft Access Driver]Optional feature not implemented
Start server side stack trace:
java.sql.SQLException: [Microsoft][ODBC Microsoft Access Driver]Optional feature not implemented
at sun.jdbc.odbc.JdbcOdbc.createSQLException(JdbcOdbc.java:6026)
at sun.jdbc.odbc.JdbcOdbc.standardError(JdbcOdbc.java:6183)
at sun.jdbc.odbc.JdbcOdbc.SQLBindInParameterFloat(JdbcOdbc.java:852)
at sun.jdbc.odbc.JdbcOdbcPreparedStatement.setLong(JdbcOdbcPreparedStatement.java:575)
at weblogic.jdbc.pool.Statement.setLong(Statement.java:369)
at weblogic.jdbc.rmi.internal.PreparedStatementImpl.setLong(PreparedStatementImpl.java:114)
at weblogic.jdbc.rmi.SerialPreparedStatement.setLong(SerialPreparedStatement.java:147)
at ejb.readMostly.StockWriterBean_u4qwd5__WebLogic_CMP_RDBMS.__WL_create(StockWriterBean_u4qwd5__WebLogic_CMP_RDBMS.java:589)
at ejb.readMostly.StockWriterBean_u4qwd5__WebLogic_CMP_RDBMS.ejbCreate(StockWriterBean_u4qwd5__WebLogic_CMP_RDBMS.java:518)
at java.lang.reflect.Method.invoke(Native Method)
at weblogic.ejb20.manager.DBManager.create(DBManager.java:519)
at weblogic.ejb20.manager.DBManager.remoteCreate(DBManager.java:489)
at weblogic.ejb20.internal.EntityEJBHome.create(EntityEJBHome.java:190)
at ejb.readMostly.StockWriterBean_u4qwd5_HomeImpl.create(StockWriterBean_u4qwd5_HomeImpl.java:78)
at ejb.readMostly.StockWriterBean_u4qwd5_HomeImpl_WLSkel.invoke(Unknown Source)
at weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:305)
at weblogic.rmi.cluster.ReplicaAwareServerRef.invoke(ReplicaAwareServerRef.java:93)
at weblogic.rmi.internal.BasicServerRef.handleRequest(BasicServerRef.java:274)
at weblogic.rmi.internal.BasicExecuteRequest.execute(BasicExecuteRequest.java:22)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:139)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
End server side stack trace
End readMostly.Client...
==========================================
please help
SP
[att1.html]

<entity-cache>
          <max-beans-in-cache>...</max-beans-in-cache>
          <read-timeout-seconds>...</read-timeout-seconds>
          <concurrency-strategy>ReadOnly</concurrency-strategy>
          </entity-cache>
          I believe this is what you are looking for and this is part of entity-descriptor.
          -- Prasad
          Aruna wrote:
          > Hi
          > I am trying to develop few entity beans which is for only reading the
          > data from the data base, As Read only entity beans are treated like stateless
          > session beans(ie lead balancing at method calls as well auto failover) in the
          > cluster. I want to know how to specify an entity bean as read only entity bean???
          > ie in deployment descriptor so that ejb container treats it as a read only entity
          > bean.
          >
          > Any help on this highly appreciated
          >
          > Thanks and Regards
          > Aruna

JDBC or Entity Beans for Read-Only Data?

Entity beans are way to slow on pulling the amount of data I need. What are the cons of just using JDBC? Is this bad programming?
One query pulls about 700 rows from 6 different tables taking up to 20 seconds. The same call using JDBC takes 2 seconds. What is the proper thing to do?

One query pulls about 700 rows from 6 different
tables taking up to 20 seconds. The same call using
JDBC takes 2 seconds. What is the proper thing to do?JDBC. Entity beans are not really suited for data across multiple tables. This can be best done with plain SQL +JDBC.

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]...
>

Can anyone explain the advantage of entity beans

Hi All,
I was wondering if anyone can explain the advantage of entity beans versus session beans. We argue that session beans can perform retrival/storage more efficiently than having an extra layer of entity beans. Basically we can't see any advantage entity beans have to offer except caching a row in a database table. I'd like to see the other side of the argument. So please if someone is an expert in this field, please advise us.
Thanks in advance for any argument
Regards,
Di

-Caching the data is one.
-Seperation of logical layer. Entity beans are used to represent the data layer, while session beans hold the business rules. This is some what nebulous as some business rules are often best implement directly in the database, although they might be replicated at a different level as well.
-Mapping a logical layout to a physical layout. For example 'customer' might have a 'fax' and 'voice' line which is represented as a Customer class with two TN classes hanging off of it. The database might represent this in one of two ways: two tables (customer and TN) or one table (customer with two tn fields).
Both of the above are more readily apparent when dealing with distributed data. If one database holds the customer and another holds the TNs, then caching of data is more relevant and dealing with the actual CRUD stuff is much more complicated. This is likely to lead to a session bean offloading the logic to another class anyways - and it becomes a defacto bean.
And a really excellent example is when the entity bean represents data that isn't accessed via normal database calls. For example the customer record might be on a legacy system which can only be accessed via screen scrapping and batch input. That single customer entity is now the front end for a large sub-system.
All such answers are usually pretty wishy-washy anyways. Why should one use java over C++? Most decisions of this nature are made because developers want to use something rather than because there is any strong technical reason to do so. And even though keeping the data layer seperate for the rules layer seems like a good idea, compromises are always required and adding layers adds complexity.

To use Entity Bean or Oracle stored Package?

Currently, in my project, Weblogic8.1 and Oracle is used, but lots of business logic is implemented using Oracle stored Packages, many of these packages have a package level readonly lookup table(like index-by table or nested table), which is populated with data from database, once the package is called, and is accessed very often in subsequent calls of stored procedures.
Since, in Weblogic server, a connection pool is maintained, and those package level lookup tables would be stored as session data in oracle PGA, I'm afraid this might cause oracle database server to be overloaded.
to fully take advantage of middleware cache service that weblogic provide, should I move those business logic out of oracle and implement them using like read only entity bean?
any help appreciated!

Its very hard to say without knowing the usage patterns of the data. It sounds like you have a lot of read-only entities. These could be spread around a WLS cluster, therefore there is more scalability and performance with this option. However, I would not neccessarily rewrite business logic from SP into EJB just for middle-tier caching.
If its a DB intensive app with lots of SQL, then if the calls are within SP's, there is only 1 call from WLS and the DBA ought o be able to tune the DB usin read-ahead and other DBA semantics. If there is locality of reference in the data, again, DB can use read-ahead better than WLS, although RO cache in middle is more scalable than DBMS.
I wouldnt rewrite business logic from SP to EJB/Entity beans to take advantage of cache, especially if there is no locality of read-only reference to data. Oracle could do this better in my opinion, especially if SP's already exist
Need for information on the usage patterns of the data - how is it CRUD'd.
I would use-case the steel threads and put them under test load to see if the SP's really are an issue, since this is an architecture decision. What state is the project at? Live/Dev? Inception?

Rad-only Entity beans are replicated?

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