EJB skeleton tied to a specific bean instance?

Is a EJB skeleton tied to a specific EJB instance? For example, if in an application every access to the EJB was done via the same skeleton, would they have to queue or would the skeleton share the pool of beans amongst the requests.
I'm assuming by skeleton to mean the remote RMI reference to the EJB returned from the create() method.
Thanks

Hi,
It partly depends on what kind of ejb we're talking about. In the case of a stateful session bean, it doesn't make sense to have concurrent invocations of the same bean. If we're talking about stateless session beans, then the container typically dispatches concurrent requests to different bean instances on different threads.
Note that strictly speaking, it would be within the
rights of the container to serialize even stateless session bean
invocations. This would certainly be a dumb thing to do, but the
application would still work.
Regards,
Ken

Similar Messages

Remote and local interface on same ejb 3.0 bean instance

Hi,
Is it posible to get remote and local interface on same ejb 3.0 bean instance.
For example get local interface of a bean and than pass it as remote to client.
Both interfaces must operate on same bean instance.
Thanks
Zlaja

yes. You can implement multiple interfaces on a single class, so you can add a local and a remote interface. One trick to avoid duplicate code is to simply make the remote interface extend the local interface; then you only have to add the @Remote annotation and you're done.
For example get local interface of a bean and than pass it as remote to client.You don't pass an instances to a client, a client looks up a remote instance of the bean through JNDI.

EJB 3.0 Stateful - Limiting number of bean instances

Hello EJB Experts,
I have just started to learn EJB 3.0 and have some basic queries. The application server that I am using is Glassfish. Please find my queries below:
1. To remove an bean instance from the container, we can use the annotation '@Remove'. I basically had 2 methods and annotated the 2nd method with '@Remove'. Whenever the 2nd method is called, the container is removing this instance also in my program. My problem is that, i might get some invalid parameter values in the 2nd method, so in that case I have to just log the error message and whenever the input parameters are correct, then only the instance should be removed. But lets say, if someone calls my 2nd method with invalid parameters, I log the message and the container removes it, but after some time if the 2nd method is called with correct parameters, then the instance will not be available. Can we programatically tell the container when to remove a bean instance?
2. From the docs, I am clear that pooling works only for 'Stateless' beans. I however (I am using 'Statuful' bean), wanted to limit the max number of instance to 2. I did below mentioned configuration in the 'sun-ejb-jar.xml' file:
<bean-cache>
                    <is-cache-overflow-allowed>false</is-cache-overflow-allowed>
                    <cache-idle-timeout-in-seconds>1</cache-idle-timeout-in-seconds>
                    <max-cache-size>2</max-cache-size>
                    <resize-quantity>0</resize-quantity>
                    <removal-timeout-in-seconds>2</removal-timeout-in-seconds>
                    <victim-selection-policy>LRU</victim-selection-policy>
          </bean-cache>
But i think, it is still creating more that 2 instances of this bean.
Please help me in getting answers to these questions. I will be very thankful for your replies.
Regards,
San
Edited by: SolarisUser1 on Jun 27, 2010 11:00 PM

@Remove is used for stateful EJBs and you call it when your client has finished using that instance of the stateful EJB.
If you are passing in parameters to the method and letting it do some work with your parameters then perhaps it should not be a remove method at all. Make it a normal method and only put cleanup related logic in the remove method. You can also throw some application exception and rollback if the parameters are not correct.

Performance Test resulting in more EJB bean instances

Hi Guys,
I am trying to profile my application using OptimizeIT.
If I conduct a load test using Load Runner , But for the test I am using only
virtual client continously repeating the same operation for a period of an hour
or so. I expect only entity bean instance to cater to the needs . What I observe
from OptimizeIT is the number of instances of entity bean continously increases
My question is when the same thread is doing the operation the Entity Bean instance
which catered to the need during the first round should be able to process client
request second time. Why should the bean instance continously increase?
Thanks in advance,
Kumar

Kumar Raman wrote:
Hi Rob,
I am unable to send the .snp file as the file size is coming out to be 6 MB which
our mail server is not allowing to send thorough (we have a corporate limit of
3MB). If U have any other way across please let me know.Did you try compressing it? Or, just split it in multiple files and
send them separately. If none of that works, send me a private email,
and I can get you a FTP upload.
>
As regards to 2 questions
1) I know as to why two instances are getting created as I can see the code here.
But I really wanted to know as to when these instances be released from the memory
? They'll be kept in the cache at least until the transaction ends. Since
you're deleting them, they'll be removed from the cache and sent to the
pool when the tx completes.
Is this going to be there till the pool size defined is filled? I haven,t defined
any pool size in our configuration. I feel the default size is 1000.
Yes, they will be in the pool, and the default pool size is 1000.
2) As regards to 2nd question , the add/delete are running in different transaction.
I wanted to know as to whether the instances created during add , be used for
delete operation as well.
They can/should be the same instance. What is your concurrency-strategy
setting for this bean? I know in the past that exclusive concurrency
was not reusing bean instances as well as some of the other concurrency
strategies (eg database / optimistic).
3) Also for each of the bean instance will there be corresponding home instances
also floating in memory. I feel the home instances should be reusable.
There's just 1 home instance for the deployment, not 1 per bean.
In case of simple Entity bean creation in weblogic, how many objects will be
created vis. a vis , home object , remote object so on...
You'll need a bean interface (local and/or remote) and a bean
implementation class.
As the number of instances which OptimizeIT shows is beyond my understanding.
I wanted to ensure is there any configuration to help me optimize these creations.
Ok, let's try to get the snapshot to me so I can help you out.
-- Rob
>
Thanks,
Kumar
Rob Woollen <[email protected]> wrote:
Kumar Raman wrote:
Hi,
Actually we are running a scenario using Load Runner tool to add arow onto a
DB using an Container managed Entity Bean. This Bean is getting instantiated
using a Session Bean. In the workflow after creation we are deletingthe row in
the table by using the remove method of the same entity bean.
If we analyze using the profiler, the number of EJB instances increasesby 2 during
add and increases by another 2 after delete.Is your session bean only creating one bean?
There seems to be 2 questions:
1) Why are you getting 2 beans on add/delete? I'm not sure if you
expect this or not.
2) Why are the beans used for the creation not being used again when
you
issue the delete?
For #2, my first question is if the create and remove are both running
in the same transaction?
I am sending the OptimizeIT (ver5.5) snapshots to you by mail.
Haven't received them yet, but they would be very helpful.
-- Rob
Please let me know as to why the instances are increasing inspite explicitlycalling
the remove method in the code.
Thanks,
Kumar
Rob Woollen <[email protected]> wrote:
We'd need a little more information to diagnose this one.
First off, if you have an OptimizeIt snapshot file (the .snp extension
not the HTML output file), I'd be willing to take a look at it and
give
you some ideas. If you're interested, send me an email at rwoollenat
bea dot com.
If you're using a custom primary key class (ie not something like
java.lang.String), make sure it's hashCode and equals method are correct.
Otherwise, it'd be helpful if you gave us some more info about yourtest
and what you're doing with the entity bean(s).
-- Rob
Kumar Raman wrote:
Hi Guys,
I am trying to profile my application using OptimizeIT.
If I conduct a load test using Load Runner , But for the test I amusing only
virtual client continously repeating the same operation for a periodof an hour
or so. I expect only entity bean instance to cater to the needs .
What
I observe
from OptimizeIT is the number of instances of entity bean continouslyincreases
My question is when the same thread is doing the operation the EntityBean instance
which catered to the need during the first round should be able toprocess client
request second time. Why should the bean instance continously increase?
Thanks in advance,
Kumar

WebLogic 10 and EJB 3.0 for Message Driven Bean

Hi,
I am trying to deploy Message Driven Bean using EJB3.0 on weblogic 10. I am using annotations and don't want to use deployment descriptors.
The Bean class:
CalculatorBean.java
import javax.ejb.*;
import javax.jms.*;
import java.sql.Timestamp;
import java.util.StringTokenizer;
@MessageDriven(activationConfig =
@ActivationConfigProperty(propertyName="destinationType",
propertyValue="javax.jms.Queue"),
@ActivationConfigProperty(propertyName="destination",
propertyValue="queue/mdb")
public class CalculatorBean implements MessageListener {
public void onMessage (Message msg) {
TextMessage tmsg=null;
try {
if (msg instanceof TextMessage) {
tmsg = (TextMessage) msg;
System.out.println
("MESSAGE BEAN1: Message received: "
+ tmsg.getText());
} else {
System.out.println
("Message of wrong type1: "
+ msg.getClass().getName());
catch (JMSException e) {
e.printStackTrace();
catch (Throwable te) {
te.printStackTrace();
My client:
import javax.naming.*;
import javax.naming.InitialContext;
import java.text.*;
import javax.jms.*;
public class MsgClient {
public static void main(String args[])
QueueConnection cnn=null;
QueueSender sender=null;
QueueSession sess=null;
Queue queue=null;
try {
java.util.Properties p = new java.util.Properties();
p.put("java.naming.factory.initial","weblogic.jndi.WLInitialContextFactory");
p.put("java.naming.provider.url","t3://10.6.74.79:7001");
Context ctx=new InitialContext(p);
//InitialContext ctx=new InitialContext(p);
queue = (Queue)ctx.lookup("queue/mdb");
QueueConnectionFactory factory = (QueueConnectionFactory)ctx.lookup("ConnectionFactory");
cnn = factory.createQueueConnection();
sess= cnn.createQueueSession(false, QueueSession.AUTO_ACKNOWLEDGE);
sender = sess.createSender(queue);
TextMessage message = sess.createTextMessage();
message.setText("This is message by Gurumurthy" );
System.out.println("Sending message: " +message.getText());
sender.send(message);
sess.close();
catch (Exception e)
e.printStackTrace();
I am compiling and creating jar file for this class. Then I am creating a .ear file for this.
The meta-inf/application.xml contains the following:
<?xml version="1.0" encoding="UTF-8"?>
<application xmlns="http://java.sun.com/xml/ns/j2ee" version="1.4"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com /xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/application_1_4.xsd">
<display-name>MDBWorking1</display-name>
<description>Application description</description>
<module>
<ejb>MDBWorking1.jar</ejb>
</module>
</application>
I don't want to use deployment descriptor (ejb-jar.xml or weblogic-ejb-jar-xml), because I want to utilize the annotation feature of EJB3.0
So, after creating the .ear file for this, and try to deploy on weblogic 10, I get the following error:
An error occurred during activation of changes, please see the log for details.
Exception preparing module: EJBModule(MDBWorking1.jar) Unable to deploy EJB: CalculatorBean from MDBWorking1.jar: [EJB:011113]Error: The Message Driven Bean 'CalculatorBean(Application: MDBWorking1, EJBComponent: MDBWorking1.jar)', does not have a message destination configured. The message destination must be set using a message-destination-link, destination-resource-link, destination-jndi-name or a resource-adapter-jndi-name.
Substituted for missing class [EJB - 11113]Error: The Message Driven Bean 'CalculatorBean(Application: MDBWorking1, EJBComponent: MDBWorking1.jar)', does not have a message destination configured. The message destination must be set using a message-destination-link, destination-resource-link, destination-jndi-name or a resource-adapter-jndi-name.
How to solve this?
Note:
I don't want to use Deployment Descriptor and all I want to use is EJB3.0's annotation feature.
Thanks,
Guru

Dear gurubbc,
I don't know if it still matters to you but you can use the javax.ejb.MessageDriven annotation to point your bean on your queue. I had the same issue like you but i could not solve it properly by switchihg to weblogic.ejb.MessageDriven.
Use the following annotation and it should work out:
@MessageDriven
(mappedName = "queue/mdb",
name = "CalculatorBean",
activationConfig = {
@ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Queue")
Here you can see that the mappedName is the JNDI name of the queue you are trying to connect to. The name is the name for your Bean, and the only property passed is the destination type.
Hope this helps.
Cheers,
Istvan

Too many bean instances

Hi
We've been struggling with this issue for a while and were wondering
if anyone has had similar exp's. reading this group and other weblogic
ones I see that entity bean instance counts have been(sic) causing
problems however we are having similar problems with stateless session
beans.
Here is our pool tag
<pool>
<max-beans-in-free-pool>2</max-beans-in-free-pool>
<initial-beans-in-free-pool>1</initial-beans-in-free-pool>
</pool>
Now, when the server starts JProbe is reporting anything up to 30
instances of EJB implementation Objects on the heap when we expect to
see at most 2.
This situation arises when the profiler invokes weblogic with no heap
switches.
if we use -ms64m -mx64m then we get even more instances on the heap.
If we set the switches to -ms128m -mx256m then the counts are up in
the hundreds and JProbe/weblogic takes as long as 30 minutes to start
up.
We are running the software on Win2000 with an 800Mhz intel processor
running in 512 MB RAM.
We have tried to get this working on Solaris8 but the server fell over
after 2.5 hours having consumed 600 MB of virtual memory.
Has any one suffered the same problem.
Also are we alone in experiencing these huge delays when starting the
server via the profiler.
Oh yes, if we start the server 'standalone' it comes up in about 1
minute.
Any help greatly appreciated
Cheers
Duncan L strang

Did you take a thread dump to see what the server was doing? I would start
there ... hopefully it is a bug in your code (those are easy to get a fix
for ;-)
Peace,
Cameron Purdy
Tangosol Inc.
Tangosol Coherence: Clustered Coherent Cache for J2EE
Information at http://www.tangosol.com/
"Duncan L" <[email protected]> wrote in message
news:[email protected]..
Hi
We've been struggling with this issue for a while and were wondering
if anyone has had similar exp's. reading this group and other weblogic
ones I see that entity bean instance counts have been(sic) causing
problems however we are having similar problems with stateless session
beans.
Here is our pool tag
<pool>
<max-beans-in-free-pool>2</max-beans-in-free-pool>
<initial-beans-in-free-pool>1</initial-beans-in-free-pool>
</pool>
Now, when the server starts JProbe is reporting anything up to 30
instances of EJB implementation Objects on the heap when we expect to
see at most 2.
This situation arises when the profiler invokes weblogic with no heap
switches.
if we use -ms64m -mx64m then we get even more instances on the heap.
If we set the switches to -ms128m -mx256m then the counts are up in
the hundreds and JProbe/weblogic takes as long as 30 minutes to start
up.
We are running the software on Win2000 with an 800Mhz intel processor
running in 512 MB RAM.
We have tried to get this working on Solaris8 but the server fell over
after 2.5 hours having consumed 600 MB of virtual memory.
Has any one suffered the same problem.
Also are we alone in experiencing these huge delays when starting the
server via the profiler.
Oh yes, if we start the server 'standalone' it comes up in about 1
minute.
Any help greatly appreciated
Cheers
Duncan L strang

Client request / response from a specific jpd instance

Hi all,
I have a business process whose instances are long running and need to be
individually accessed by multiple clients (mostly pageflow controllers on
numerous portlets).
How can I possibly target a client receive/send call to/from a specific
instance of a business process (not a specific JPD class, rather a specific
INSTANCE of a JPD that is already running and has not necesarily need
started by the current pageflow controller etc.)???
This seems like a pretty fundamental requirement - I'd hate to have to use
message brokers and message filter for all interchanges. Is that my only
option?
I looked into dynamic binding, but that seems to be a method for dynamically
selecting between multiple JPD classes - and not running instances of those
classes.
cheers,
Markus

Where is this getInstanceId() method. This does not seem to be a method of ProcessDefinition.
I can only see the getConversationId() and setConversationId() methods. The getConversationId()
method returns null.
"Markus Blumrich" <[email protected]> wrote:
This helps immensely - thank you for taking the time to post.
Really I think BEA should address this rather basic scenario in a more
developer friendly way - and if they have, then publish a how-to.
cheers,
Markus
"Yueming Xu" <[email protected]> wrote in message
news:[email protected]...
We had the same request, and I figured it out the hard way. The solutionis actually
pretty simple.
(1) When the JPD processes the initial request, it should usegetInstanceId()
to get the conversation ID and store it somewhere the client app canfind
(e.g.,
in an Entity bean), or return it to your client, and manage it at theclient.
(2) At a later time, client app may retrieve the conversation ID, andthen
send
follow-up requests to the JPD instance (which is actually an Entitybean
whose
primary key is the conversation ID).
(3) To send a request to a specific JPD instance using a process control,you
need to first call setConversationID(), and then call the request method.
Hope this helps.
Yueming
"Markus Blumrich" <[email protected]> wrote:
Hi all,
I have a business process whose instances are long running and need
to
be
individually accessed by multiple clients (mostly pageflow controllers
on
numerous portlets).
How can I possibly target a client receive/send call to/from a specific
instance of a business process (not a specific JPD class, rather aspecific
INSTANCE of a JPD that is already running and has not necesarily need
started by the current pageflow controller etc.)???
This seems like a pretty fundamental requirement - I'd hate to haveto
use
message brokers and message filter for all interchanges. Is that myonly
option?
I looked into dynamic binding, but that seems to be a method fordynamically
selecting between multiple JPD classes - and not running instancesof
those
classes.
cheers,
Markus

How to get all property names and values of an bean instance at runtime?

How can I get all property names and values of an bean instance at runtime?
(The class of the bean instance is dynamic and I can not know before I write the code .)

Look at Class. It has a way to get at all public methods and attributes.
If you need to get to private attributes you can do what the Introspector does and expect the methods to follow the Bean pattern and pull the attributes out based upon that. Privates are all hidden from direct access but through the Bean Pattern they can be figured out.

Problem with EJB skeleton classloader

Hi
We have been migrating an enterprise application from Weblogic 7 to 9.2 and experienced strange problem with EJBs. Our EAR contains (beside the other elements) an EJB module with EJBs and some common POJO classes inside. At the deploy and run phase everything seems working fine, but when the remote client invokes a method which receives one of the common classes as a parameter we get ClassNotFoundException on the server side (talking precisely, the exception is thrown from the EJB skeleton, trying to unmarshall the parameter).
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The other JARs have no problem loading the content of our EJB module (including the common classes, which cause the problem).
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The problem was fixed by upgrading to version 9.2.1

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CODE:
package webclass;
import java.io.*;
import java.sql.*;
import java.util.*;
import webclass.LoginBean.*;
public class LoginDataBean
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ERROR:
cannot resolve symbol class LoginBean
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thanks, but look at the new code i modified still given error on not resolving the class LoginBean in the class LoginDataBean. here is the new code.
package webclass;
import java.io.*;
import java.sql.*;
import java.util.*;
public class LoginDataBean
     private Connection cn;
     private PreparedStatement addRecord;
     public LoginDataBean()throws Exception
          Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
          cn = DriverManager.getConnection("jdbc:odbc:portal");
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I'm runing powershell commnad New-SPConfigurationDatabase ,
there is a parameter is
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Awen

Hi,
Just use the instance name for Databse server...like below.
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Sangeetha
-Sangeetha

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What are the necessary elements in ejb-jar.xml with CMP entity bean

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some elements r missing
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Anand Pritam

According to the ejb-jar.xml dtd ejb-name, ejb-class, persistence-type, prim-key-class, reentrant are the required elements for an entity bean.
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          local?, ejb-class, persistence-type, prim-key-class,
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How exchange messages between two user-bean instances?

Hi,
I would like to let several user to log-in my web site (I'm using tomcat) and then let them exchange some messages until they are logged-in. Is there a way using JSF?
I was thinking about implementing a list of messages inside each user-bean. The user should know that other users are logged-in, that could be listed in a table, and click on its name. I would like that the click action create an item in the list valiable of the selected user. Is that possible using JSF? I didn't find any of such kind of communication between two user-bean instances.
Do you have any hints? Is that the right way or is there other possibilities?
Thanks

You could get hold of a map of sessions in the application scope. Make use of HttpSessionListener to add/remove sessions to/from the map.
JSF is just another component based MVC framework on top of JSP/Servlet. Everything which you can do in JSP/Servlet is just still possible. You only need to understand how JSF works under the hood.

Restrict number of stateless bean instances

i need to restrict number of stateless bean instances. Am working on EJB3.0 and jboss.
I have even modified the following in standardjboss.xml but, still am not able to restrict.......
<container-pool-conf>
<MaximumSize>10</MaximumSize>
<strictMaximumSize>true</strictMaximumSize>
</container-pool-conf>
Is there any other way?
Thank in advance

all the config files are different in jboss for the ejb3 stuff (rather annoying). assuming you want to make this change globally, you need to alter the deploy/ejb3-interceptors-aop.xml file. at the end of the "Stateless Bean" domain there is an annotation element which defines the pool configuration (it's basically a copy of the java annotation embedded in the xml file).

EJB skeleton tied to a specific bean instance?

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