Where to store stateless session bean reference?
Hi,
I am currently writing my first ejb-jar <-> web app pair of applications. Thanks to EJB3.0 and J2EE5 the ejb part was quite easy to learn. J2EE has become a really cool platform in its recent version.
On the Web Application side I have the following question:
Where should references to stateless session beans generally be stored? Is it OK to store them in the ServletContext? In the HTTP session? Or is it better to do a JNDI lookup on a per request basis?
Application Scope (ServletContext) if many servlets use it, initialised by applicationListener (big advantage is that your webapp will not load if bean lookup fails.
Page scope (instance variable of servlet ), initialised in init() method of servlet if only needed by this page (servlet).
Session scope: makes no sense for stateless session beans, useful for stateful session beans only
Request scope: rarely used for this because JNI lookup overhead.
Hope this helps, R
Similar Messages
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Where to write SQL query in a Stateless Session Bean?
Hi
I want to query a database table from a Stateless Session Bean (SSB). I have the getter and setter methods. And am connecting to the database in ejbCreate and disconnecting in ejbRemove methods. But where should I query the database to retrieve the data? In case of a entity bean it is written in the ejbLoad but where in SSB.
Thanks in advance
SivaStateless Session Bean as its name indicates, it has no state, ie it should have no member variables. In another word, SLSB is method based.
Hence, if somehow you need to access to the database in one of the method, you have to open db connection and query the table in that method.
BTW, a Stateless Session Bean should not have getter and setter methods, because it should not keep any stateful information.
--lichu -
Call stateless session bean EJB 2.0 from Webdynpro Java UI
Hello,
Can someone please tell me asto how to call a stateless session bean EJB 2.0 from Webdynpro Java UI?
The NWDS version is 7.0.
Thanks and Regards,
AryaHi Aryadipta
Please check this pdfs
https://www.sdn.sap.com/irj/scn/index?rid=/library/uuid/b00917dc-ead4-2910-3ebb-b0a63e49ef10&overridelayout=true
Steps for calling stateless session bean in Webdynpro java
Go to NWDS -> open perspective ->j2ee
select EJB Module Project ->create a project with name
Open the Project -->RC on ejb-jar.xml -> Select new --> EJB
Give name to EJB Bean (First letter should be in capital letters)
select the type of bean as Stateless session bean and give the package name to store that EJB bean.
After that Expand ejb-jar.xml and then select the <projectEJB>
Double click on this on method tab double click you will get business method where we will create the methods for business logic
Double click on projectEJB and then RC on bean tab and write required business logic in bean window as follows(based on requirement we will design a business logic).
After writing the business logic go to project -> rebuild
Till now we have created one EJB jar file
then go to File-->Enterprise Application Project -->create a project (projectEAR)
After creating a project click on next-> here we will have ear projects and then we select specific project required for our application.(here select projectEJB)
After that Calculate EAR project will be available on j2ee explorer.
Right click on <Bean> here
select New->Web Service->give a name to webservice and select Default configuration type as simple SOAP
-->click next -> Finish.
That webservice and related are created in ejb-jar.xml .
Expand the ejb-jar.xml.and double click on < webservice>
RC ProjectEJB -> Build EJB Archive RC on CalculateEAR ->Build applicationarchive.
Expand the projectEAR->RC on CalculateEAR.ear->Deploy to J2EE Engine
Double click on calculateEAR.ear ->Webservice navigator tab ->we eill servers expand the node
select the specific WebService
Here we test the webservice by click on Test and test it.
After that go to Web dynpro perspective ->create one webdynpro Project and one component
RC on model> Select import Web Service model(last)>give model name and package
and select radio button as local file system or URL
Go to WSnavigator->copy the WSDL path and paste it in model WSDL path and click on finish.
from here onwards steps are same as that adaptive RFC model
Hope it helps
Thanks
Tulasi Palnati
Edited by: Tulasi Palnati on Aug 26, 2009 12:15 PM
Edited by: Tulasi Palnati on Aug 26, 2009 12:43 PM -
How to get stateful and stateless session bean in second jsp
I create stateful session bean in the first jsp, then how can I get the stateful session bean in the second jsp? I find that somebody store the bean in HttpSession.
If I store the stateful session bean in HttpSession, then I can get it in the second jsp. My problem is that I can store the stateless session bean in HttpSession, and get it in the second jsp. Then, both stateful and stateless can maintain the state in the second jsp. What is the difference between stateful and stateless session bean in this case ?
I understand the definition of stateful and stateless session bean, but I'm confuse how to use session bean. Can anyone provide sample jsp to show difference of stateful and stateless? How the stateful session bean can maintain the state for the client?Greetings,
I create stateful session bean in the first jsp, then how can I get the stateful session bean in the
second jsp? I find that somebody store the bean in HttpSession.Which is the correct scope for sharing client-specific data when 'request' scope is insufficient.
If I store the stateful session bean in HttpSession, then I can get it in the second jsp. My problem is
that I can store the stateless session bean in HttpSession, and get it in the second jsp. Then, bothWhy is that a "problem"? Does your application not require the stateless bean to be shared? If so, then don't store the EJBObject reference in the session...
stateful and stateless can maintain the state in the second jsp. What is the difference betweenWhat do you mean by this exactly?..
stateful and stateless session bean in this case ?Statefulness of session beans is in regard to maintaining client state (er, in all cases). If your "stateless" bean is receiving information from the client (i.e. its caller) - either through a create method or a business method - and that information is available (retrievable from the bean) on subsequent method calls, then that bean is, in fact, stateful - regardless of how it is deployed.
I understand the definition of stateful and stateless session bean, but I'm confuse how to use
session bean.The correct question, it here seems, is "when" to use which type... Use a "stateful" bean when information about (from) the client (i.e. the caller) must be maintained across method calls of the bean. Use a "stateless" bean for general business methods that do not depend on "prior knowledge" of the client (i.e. the caller).
Can anyone provide sample jsp to show difference of stateful and stateless? How the statefulA "sample JSP" would yield nothing additional... The semantics of calling, using, and "persisting", bean references are always the same - regardless of type or class. However, the reason(s) for using one over the other depends entirely on the needs of your application.
session bean can maintain the state for the client?I recommend that you spend more time learning about EJBs generally. In particular, it seems you require more fundamental understanding of their scope and lifecycle. Refer to sections 4, 6, and 7 of the EJB 2.0 Specification.
Regards,
Tony "Vee Schade" Cook -
Transaction not rolling back in stateless session bean
Hi,
I am facing a problem...
I have one stateless session bean which does multiple updates in SYBASE database.I
am using non-transactional datasource. Bean calls a method of data access obejct
whcih internally calls more than one one mehtod to update different tables.If
any of update fails then I am explicitly thorwing EJBException. Still it is not
rolling back.
I have one more application where similar situation is there but only difference
is that there we have Entity bean and updates are being done through store method.
In that case with same datasource it is rolling back perfectly.
I have tried with transactional datasource as well but it didn't work.Then I tried
to put setAutoCommit(false) in my connection class which gives me connection.But
then it is not allowing me to enter into my application.
In deployment descriptor for both the beans transaction attribute is required
for all methods.
Regards.
Rahul.
Hi,
I am facing a problem...
I have one stateless session bean which does multiple updates in SYBASE database.I
am using non-transactional datasource. Bean calls a method of data access obejct
whcih internally calls more than one one mehtod to update different tables.If
any of update fails then I am explicitly thorwing EJBException. Still it is not
rolling back.
I have one more application where similar situation is there but only difference
is that there we have Entity bean and updates are being done through store method.
In that case with same datasource it is rolling back perfectly.
I have tried with transactional datasource as well but it didn't work.Then I tried
to put setAutoCommit(false) in my connection class which gives me connection.But
then it is not allowing me to enter into my application.
In deployment descriptor for both the beans transaction attribute is required
for all methods.
Regards.
Rahul.
-
Registering EJB/Stateless Session Bean Web Service in Registry
Hi verybody!
I would like to know how I can register a Web Service in a registry. The web service is implemented as a session bean.
The problem is not the actual code to register the service, but how and where can I hook this code into the application so that it is started when the application server is started.
I've read the Sun J2EE tutorial which registered the service in the moment when the context for the servlet for an ordinary web client was created. This is not what I want. I would like to register the service when starting the EJB container, without the need to give it a kick from some external interface.
Any help or ideas will be greatly welcome
Regards
PI1. But I thought you were using a 'stateful session bean'?
2. For stateless session beans, there is no direct link between a remote reference and an instance of the bean. It is safe to hang on to the remote reference as long as you would like, of course it may go stale if the server dies. You will also find that the create() method does not actually contact the server, so doing it each usage costs very little. So, either way you should be fine.
3. As for memory leaks, make sure that you are closing all statements, result sets, etc. promptly. These are commonly the problem. Also, use hprof or some other profile tool to determine what types of data you are allocating and (with better tools) what types of data you may be holding on to references to.
Chuck -
EJB: Stateless Session Bean create() Question.
Lets say I have a stateless session bean that fetches data from my database. The point of the bean is to just do large SQL searches and funnel data back to the client. The prolem I have is that I am somehow fighting memory leaks. Despite having checked the code a number of times, the memory usage on my appserver continues to climb no matter what I do. I have theorized that the problem might be in the way Im using ma DataFetchBean (DFB).
When I start the client, he obtains a user session. This is a stateful session bean that he uses for almost all communication with the server. Then I call "getDataFetchBean" in the user session which calls DataFetchBeanHome.create(). Then the client holds onto the returned reference, using it for the live of his connection. As he disconnects, he calls remove on the bean.
Question is this:
1) Is it better for me to call create() prior to each call to the stateless session bean ?
2) Do you have any theories on why im loosing memory with this setup?
TIA
-- Rob1. But I thought you were using a 'stateful session bean'?
2. For stateless session beans, there is no direct link between a remote reference and an instance of the bean. It is safe to hang on to the remote reference as long as you would like, of course it may go stale if the server dies. You will also find that the create() method does not actually contact the server, so doing it each usage costs very little. So, either way you should be fine.
3. As for memory leaks, make sure that you are closing all statements, result sets, etc. promptly. These are commonly the problem. Also, use hprof or some other profile tool to determine what types of data you are allocating and (with better tools) what types of data you may be holding on to references to.
Chuck -
EJB Stateless Session Bean Transactions
I have a stateless session bean.
Its deployment descripter references a JDBC DataSource.
It uses container managed transactions.
If I make JDBC calls, within a business method
of this stateless session bean, with the referred datasource, is it attached
to a container managed transaction?If I make JDBC calls, within a business method
of this stateless session bean, with the referred
datasource, is it attached
to a container managed transaction?IIRC, yes. For CMT, the container will roll back any JDBC actions carried out by a method if it fails. -
StreamCorruptedException from Stateless Session bean to java class
Hi all,
We have 2 servers, a ColdFusion App server which contains suns jdk 1.4.2 and websphere appserver using Ibm jdk, 1.4.2. On Server 1, we have a standalone java class which does a stateless session bean lookup and requests a service from it. On server 2(websphere), we have a stateless session bean deployed which connects to a database using a jndi lookup, executes a query and returns back a CachedRowSet object (which populates the ResultSet from the above query.) In some cases, session bean returns back an array of objects or String objects or just plain int values.
When the java class on server 1 invokes the methods returning CachedRowSet, we are getting a StreamCorruptedException, whereas on the server side, there is no exception. everything gets executed fine on websphere. This is the case only for CachedRowSet and not for other return types(as mentioned earlier the session bean returns an array of object in some cases which the java class on server 1 is successfully able to use).
This is what the piece of code look like on server 1:
// First gets a StatelessSessionBean using suns InitialContextFactory
Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.cosnaming.CNCtxFactory");
env.put(Context.PROVIDER_URL,"iiop://localhost:2809");
System.out.println("Creating initial context");
Context ctx = new InitialContext(env);
System.out.println("Initial context created.");
Object homeObj = ctx.lookup("cell/nodes/localhost/servers/server1/ejb/SSBHome");
SSBHome eHome = (SSBHome)PortableRemoteObject.narrow(homeObj,SSBHome.class);
System.out.println("Got Home");
SSB eBean = eHome.create();
CachedRowSet crs = eBean.getAccts(param1, param2);
//This is the line of code which throws the exception.
The stacktrace shoows as follows:
Got Home
java.io.StreamCorruptedException
at com.sun.corba.se.internal.io.IIOPInputStream.inputRemoteMembersForReadFields(IIOPInputStream.java:1675)
at com.sun.corba.se.internal.io.IIOPInputStream.readFields(IIOPInputStream.java:1595)
at com.sun.corba.se.internal.io.InputStreamHook.readFields(InputStreamHook.java:177)
at java.math.BigInteger.readObject(BigInteger.java:3034)
at com.sun.corba.se.internal.io.IIOPInputStream.readObject(Native Method)
at com.sun.corba.se.internal.io.IIOPInputStream.invokeObjectReader(IIOPInputStream.java:1298)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObject(IIOPInputStream.java:908)
at com.sun.corba.se.internal.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:261)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:247)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1084)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:293)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:1484)
at com.sun.corba.se.internal.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:1893)
at com.sun.corba.se.internal.io.IIOPInputStream.defaultReadObjectDelegate(IIOPInputStream.java:424)
at com.sun.corba.se.internal.io.InputStreamHook.defaultReadObject(InputStreamHook.java:163)
at java.math.BigDecimal.readObject(BigDecimal.java:1084)
at com.sun.corba.se.internal.io.IIOPInputStream.readObject(Native Method)
at com.sun.corba.se.internal.io.IIOPInputStream.invokeObjectReader(IIOPInputStream.java:1298)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObjectUsingFVD(IIOPInputStream.java:1182)
at com.sun.corba.se.internal.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:259)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:247)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:948)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:289)
at com.sun.corba.se.internal.corba.TCUtility.unmarshalIn(TCUtility.java:266)
at com.sun.corba.se.internal.corba.AnyImpl.read_value(AnyImpl.java:561)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_any(CDRInputStream_1_0.java:635)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_any(CDRInputStream.java:260)
at com.sun.corba.se.internal.javax.rmi.CORBA.Util.readAny(Util.java:100)
at javax.rmi.CORBA.Util.readAny(Util.java:90)
at com.sun.corba.se.internal.io.ValueHandlerImpl.read_Array(ValueHandlerImpl.java:586)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:244)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1084)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:293)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:1577)
at com.sun.corba.se.internal.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:1796)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObject(IIOPInputStream.java:913)
at com.sun.corba.se.internal.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:261)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:247)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:948)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:289)
at com.sun.corba.se.internal.corba.TCUtility.unmarshalIn(TCUtility.java:266)
at com.sun.corba.se.internal.corba.AnyImpl.read_value(AnyImpl.java:561)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_any(CDRInputStream_1_0.java:635)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_any(CDRInputStream.java:260)
at com.sun.corba.se.internal.javax.rmi.CORBA.Util.readAny(Util.java:100)
at javax.rmi.CORBA.Util.readAny(Util.java:90)
at com.sun.corba.se.internal.io.ValueHandlerImpl.read_Array(ValueHandlerImpl.java:586)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:244)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1084)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:293)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:1577)
at com.sun.corba.se.internal.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:1796)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObject(IIOPInputStream.java:913)
at com.sun.corba.se.internal.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:261)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:247)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1084)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:293)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:1577)
at com.sun.corba.se.internal.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:1796)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObject(IIOPInputStream.java:913)
at com.sun.corba.se.internal.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:261)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:247)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1084)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:293)
at com.EJBProj._SSB_Stub.getAccts(_SSB_Stub.java:240)
at com.test.Test1.getAccts(Test1.java:101)
at com.test.Test1.<init>(Test1.java:65)
at com.test.Test1.main(Test1.java:81)
java.io.IOException: Unable to read value from underlying bridge : Serializable readObject method failed internally
at com.sun.corba.se.internal.io.IIOPInputStream.throwExceptionType(Native Method)
at com.sun.corba.se.internal.io.IIOPInputStream.defaultReadObjectDelegate(IIOPInputStream.java:446)
at com.sun.corba.se.internal.io.InputStreamHook.defaultReadObject(InputStreamHook.java:163)
at java.math.BigDecimal.readObject(BigDecimal.java:1084)
at com.sun.corba.se.internal.io.IIOPInputStream.readObject(Native Method)
at com.sun.corba.se.internal.io.IIOPInputStream.invokeObjectReader(IIOPInputStream.java:1298)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObjectUsingFVD(IIOPInputStream.java:1182)
at com.sun.corba.se.internal.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:259)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:247)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:948)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:289)
at com.sun.corba.se.internal.corba.TCUtility.unmarshalIn(TCUtility.java:266)
at com.sun.corba.se.internal.corba.AnyImpl.read_value(AnyImpl.java:561)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_any(CDRInputStream_1_0.java:635)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_any(CDRInputStream.java:260)
at com.sun.corba.se.internal.javax.rmi.CORBA.Util.readAny(Util.java:100)
at javax.rmi.CORBA.Util.readAny(Util.java:90)
at com.sun.corba.se.internal.io.ValueHandlerImpl.read_Array(ValueHandlerImpl.java:586)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:244)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1084)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:293)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:1577)
at com.sun.corba.se.internal.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:1796)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObject(IIOPInputStream.java:913)
at com.sun.corba.se.internal.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:261)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:247)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:948)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:289)
at com.sun.corba.se.internal.corba.TCUtility.unmarshalIn(TCUtility.java:266)
at com.sun.corba.se.internal.corba.AnyImpl.read_value(AnyImpl.java:561)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_any(CDRInputStream_1_0.java:635)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_any(CDRInputStream.java:260)
at com.sun.corba.se.internal.javax.rmi.CORBA.Util.readAny(Util.java:100)
at javax.rmi.CORBA.Util.readAny(Util.java:90)
at com.sun.corba.se.internal.io.ValueHandlerImpl.read_Array(ValueHandlerImpl.java:586)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:244)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1084)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:293)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:1577)
at com.sun.corba.se.internal.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:1796)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObject(IIOPInputStream.java:913)
at com.sun.corba.se.internal.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:261)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:247)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1084)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:293)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:1577)
at com.sun.corba.se.internal.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:1796)
at com.sun.corba.se.internal.io.IIOPInputStream.inputObject(IIOPInputStream.java:913)
at com.sun.corba.se.internal.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:261)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:247)
at com.sun.corba.se.internal.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:209)
at com.sun.corba.se.internal.iiop.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1084)
at com.sun.corba.se.internal.iiop.CDRInputStream.read_value(CDRInputStream.java:293)
at com.EJBProj._SSB_Stub.getAccts(_SSB_Stub.java:240)
at com.test.Test1.getAccts(Test1.java:101)
at com.test.Test1.<init>(Test1.java:65)
at com.test.Test1.main(Test1.java:81)
Again, everything seems to work fine on websphere server.
Any Clue of why this is happening?
All suggestions are greatly appreciated.
Thanks
Neorav
Message was edited by:
NeoravBSorry for the confusion!
The solution mentioned above is not the right solution.
The above given code works fine irrespective of having corbaloc in the url, if you are working in the IBMs jvm.
It fails if you are working in suns jvm.
Anyone with any idea whats missing here.
Thanks a lot for any suggestion/ideas
Neorav -
Help Connecting A Stateless Session Bean To MySQL Database
Hi, I'm trying to connect a simple stateless session bean that has been
deployed using the admin console to a MySQL database that has been
set up and pinged using the JDBC Resources/Connection Pools part of the
admin console.
When I attempt to connect to the database using the session bean I get the
following error message:
Exception in thread "main" java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.RemoteException: ; nested exception is:
java.sql.SQLException: No database selected
at com.sun.corba.ee.impl.javax.rmi.CORBA.Util.mapSystemException(Util.java:161)
at javax.rmi.CORBA.Util.mapSystemException(Unknown Source)
at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.invoke(StubInvocationHandlerImpl.java:142)
at com.sun.corba.ee.impl.presentation.rmi.bcel.BCELStubBase.invoke(Unknown Source)
at DBDynamicStub.testDatabase(_DB_DynamicStub.java)
at DBClient.main(DBClient.java:9)
Caused by: java.rmi.RemoteException: ; nested exception is:
java.sql.SQLException: No database selected
at com.sun.ejb.containers.InvocationHandlerUtil.throwRemoteException(InvocationHandlerUtil.java:96)
at com.sun.ejb.containers.EJBObjectInvocationHandler.invoke(EJBObjectInvocationHandler.java:141)
at $Proxy26.testDatabase(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.sun.corba.ee.impl.presentation.rmi.ReflectiveTie._invoke(ReflectiveTie.java:123)
at com.sun.corba.ee.impl.protocol.CorbaServerRequestDispatcherImpl.dispatchToServant(CorbaServerRequestDispatcherImpl.java:648)
at com.sun.corba.ee.impl.protocol.CorbaServerRequestDispatcherImpl.dispatch(CorbaServerRequestDispatcherImpl.java:192)
at com.sun.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequestRequest(CorbaMessageMediatorImpl.java:1709)
at com.sun.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequest(CorbaMessageMediatorImpl.java:1569)
at com.sun.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleInput(CorbaMessageMediatorImpl.java:951)
at com.sun.corba.ee.impl.protocol.giopmsgheaders.RequestMessage_1_2.callback(RequestMessage_1_2.java:181)
at com.sun.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequest(CorbaMessageMediatorImpl.java:721)
at com.sun.corba.ee.impl.transport.SocketOrChannelConnectionImpl.dispatch(SocketOrChannelConnectionImpl.java:469)
at com.sun.corba.ee.impl.transport.SocketOrChannelConnectionImpl.doWork(SocketOrChannelConnectionImpl.java:1258)
at com.sun.corba.ee.impl.orbutil.threadpool.ThreadPoolImpl$WorkerThread.run(ThreadPoolImpl.java:409)
Caused by: java.sql.SQLException: No database selected
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2851)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1531)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1622)
at com.mysql.jdbc.Connection.execSQL(Connection.java:2379)
at com.mysql.jdbc.Connection.execSQL(Connection.java:2306)
at com.mysql.jdbc.Statement.executeQuery(Statement.java:1192)
at DBBean.testDatabase(DBBean.java:45)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.sun.enterprise.security.SecurityUtil$2.run(SecurityUtil.java:153)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.enterprise.security.application.EJBSecurityManager.doAsPrivileged(EJBSecurityManager.java:950)
at com.sun.enterprise.security.SecurityUtil.invoke(SecurityUtil.java:158)
Obviously this means that the bean can't connect to the database but I am
unsure why this is. When I set up the database using the admin console
I set the the jndi name to jdbc/test and I've tried using the following look up
code to find the database that is referenced by the JNDI name:
Context context = new javax.naming.InitialContext();
DataSource ds = (DataSource) context.lookup("jdbc/test");
and also
Context context = new javax.naming.InitialContext();
DataSource ds = (DataSource)context.lookup("java:comp/env/jdbc/test");
Neither of these methods work.
When I look at the JNDI Tree Browsing window which is available from the
admin console there is no mention of the database at all, there are four
items in the three, they are:
UserTransaction
->jdbc
->ejb
DBBean
Do I need to add a JNDI reference somewhere in order for the bean to locate
the database? I thought that when I created the database in the admin
console and specified a JNDI name this would be all that's required in order
for beans to locate the database, obviously not.
If anyone can offer any advice at all I would be very very grateful.
Ianstmt.execute("use YOUR_DATABASE_NAME");
// then your db queries.This approach works for me.
It also works to specify the database in the query like this:
InitialContext initCtx = new InitialContext();
Context envCtx = (Context) initCtx.lookup("java:comp/env");
DataSource ds = (DataSource) envCtx.lookup("jdbc/myDB");
Connection conn = ds.getConnection();
try {
Statement statement = conn.createStatement();
ResultSet rs = statement.executeQuery("select * from myDB.news");
...As you can see I added myDB. to the query.
But why is this necessary?
If I use DriverManager instead, this is NOT necessary. Like this:
Connection connection = null;
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/myDB", "username", "password");
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery("select * from news");
...Why do I not have to run the query statement.execute("use YOUR_DATABASE_NAME"); or specify the database name in the query statement.executeQuery("select * from myDB.news"); when I use DriverManager to obtain a Connection when I have to do that when using a DataSource?
It don't seem very efficient to have to run the extra query ( use db-name ) before I run any other query in my application. -
A tough one for EJB experts - Stateless session bean spec question
I am busy learning more about EJBs and came across something confusing regarding the legal operations in the various container callback methods for stateless session beans.
Specifically, the EJB spec states that in the ejbCreate() method, the SessionContext can be used to obtain a reference to the EJB Object. Now this makes perfect sense with stateful session beans, since the ejbCreate() method isn't called until a client is creating a bean and the container has linked that bean to the client's EJB Object. However, it is my understanding that when it comes to stateless session beans, the container creates the beans and adds them to the bean pool at its leisure. It is not until a business method is called by a client that a stateless bean is actually linked to an EJB object. So, how is it that a stateless bean could ever obtain a reference to an EJB Object from within ejbCreate(). Which EJB Object would it be linked to? This operation just doesn't appear to make sense in that context.
Can anyone clarify this for me?Interesting question. I have such questions all the time! Here's a link to a similar discussion
http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=70&t=000905
Also, I tried this using Weblogic 8.1. Tried to access the EJBObject in ejbCreate before any business method was invoked. I did this by specifying a value for initial-beans-in-free-pool and found that the hash code for the EJBObject was the same for all the bean instances that were created on startup.
I then invoked a business method and accessed the EJBObject in that method. Again the hash code for the object was the same as the one created on startup.
Seemed to be that there is a 1:n relation between the EJBObject and bean instances.
This may be container specific. The spec says the user should be able to invoke the getEJBObject() method in ejbCreate(), its upto the container to comply with it. -
JNDI lookup of a Stateless Session bean from another stateless session bean
Hi,
I am working on SAP Netweaver. We have created a stateless session bean which is finally deployed as a webservice. From this stateless session bean we need to call another stateless session bean as a local reference.
I have done the following.
1. Added JNDI-Name to the ejb-j2ee-engine.xml.
2. My lookup code is as follows
Context context = null;
Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sap.engine.services.jndi.InitialContextFactoryImpl");
context = new InitialContext(env);
Object ejbObj = context.lookup("MyBean");
But i get the NamingException .Here MyBean is the jndi-name provided in the ejb-j2ee-engine.xml.
Can somebody tell me what i am doing wrong.
Thanks
PriyaHi,
Thanks for your replies.I did as you had suggested.I added ejb-local-ref to the ejb-jar.xml and i provided ejb-ref as MyBean.
My lookup code uses the string
ctxt.lookup("localejbs\MyBean");
But still i get Naming Exception.
I tried something different yesterday.
I changed the code to use
InitialContext ctxt = new InitialContext();
ctxt.lookup("localejbs/"+ pathfromJNDIRegistry);
and this time i did not get Naming exception but i got RemoteException saying there was error loading the class.
Is there something i need to add somewhere for the classloader to be able to find and load this class in the second scenario.
Please suggest me which method to go for amongst the two and what is the missing information i need to add.
Thanks
Priya -
A question about entity manager in stateless session bean.
JSR 220 ejbcore, page 47 : stateless session bean: All business object references of the same interface type for the same stateless session bean have the "same object identity", which is assigned by the container.
So, if we have two session beans in client code...
@EJB Cart cart1;
@EJB Cart cart2;
then cart1.equals(cart2)==true
If we declare entity manager in stateless session bean:
@PersistenceContext( unitName="ds" ,type=PersistenceContextType.TRANSACTION)
private EntityManager em;If cart1 and cart2 are the same reference, do we have any problem when using the same reference(maybe the same em? ) to get data from db?If cart1 and cart2 are the same reference, do we have
any problem when using the same reference(maybe the
same em? ) to get data from db?No. In EJB, there is a distinction between the EJB reference and the bean instance.
Each time you make an invocation on an EJB reference for a stateless session bean,
the container can choose any instance of that bean's bean class to process the
invocation. That's true whether you invoke the same reference multiple times or
two difference references to the same bean.
Each bean instance is guaranteed to be single-threaded. -
Stateless session beans and idle timeouts (weblogic 10.3.1)
Need clarification about stateless session beans and the idle-timeout-seconds setting.
Situation is this – we have a process that is timing out due to an API call to a very slow Authentication server.
I am trying to resolve this with a code change, but need to further other understand what the server is actually doing.
We have a session bean which calls another which is calling a util class that does all the work and returns the results back up to the initial session bean. I have left out the ejbName in these examples (it’s irrelevant here).
Example:
SessionBean1 // basically called just once a day
@Session(defaultTransaction = Constants.TransactionAttribute.SUPPORTS,
enableCallByReference = Constants.Bool.TRUE,
type = Session.SessionType.STATELESS,
transTimeoutSeconds = "0",
initialBeansInFreePool = "0",
maxBeansInFreePool = "20")
Methods
@RemoteMethod() public boolean getUserList(String adminGroup) {
Map usrList = getUserList(adminGroup);
Private Map getUserList(String adminGroup) {
return SessionBean2.getUsers(adminGroup);
SessonBean2
@Session(defaultTransaction = Constants.TransactionAttribute.SUPPORTS,
enableCallByReference = Constants.Bool.TRUE,
type = Session.SessionType.STATELESS,
transTimeoutSeconds = "0",
initialBeansInFreePool = "3",
maxBeansInFreePool = "20")
Method
@RemoteMethod() public Map getUsers(String adminGroup) throws RemoteException {
return javaUtilClass.getUsers(adminGroup);
JavaUtilClass
Method
public Map getUsers(String adminGroup) throws RemoteException {
// This is where the work happens, calling the Authentication server to get a complete
// list of users for an admin group. When the user list is around 1500 entries, this can
// take an hour. Did I mention this server is very slow? It’s about this threshold of 1500
// that causes the timeout.
return Map of users
First thought, just bump the idle-timeout-seconds setting for the session beans (from the default 600), but that would be a temporary solution until the user list grew larger.
Second thought, refactor the call to the Authentication Server API to get the user list in blocks of data (say 400 at a time) and decreasing the call/response time between the method getUsers and the API call. This would still occur in the JavaUtilClass, so I am unsure this would make a difference. The session beans would still be idle and subject to timeout, correct?
Would setting initialBeansInFreePool to 1 in SessionBean1 make any difference?
Or should I be looking at replicating the re-factored method from the JavaUtilClass in SessionBean1 where the user list is being used so that the API calls come back to it and keep it 'active'?
Thanks for any advice you could give me on this.Hi
regarding timeouts, there are two ways:
1.- Changing the settings in the JTA WebLogic domain , called "Timeout Seconds". This will affect globally to all EJB deployed in the domain.
or
2.- Specified directly in the bean with a weblogic annotation, like this:
@TransactionTimeoutSeconds(value = 300)I hope this will help you.
Regards.
Felipe -
Java.io in J2ee stateless session bean, general questions about debugging
Doing conventional Java IO (with java.io functions and classes such as
PrintWriter and println) in a Enterprise bean has been discussed before
in this and other forum. We know that the EJB specification says not to do it.
(For example the EJB 2.0 spec, 24.1.2) says that an enterprise
bean must not use the java.io package to attempt to access files and
directories int he file system."
The discussion in various forums including this one is that
a) using java.io in a bean would impact portability, ability to
move the bean for load balancing
b) However, this is not always an an issue and it may be reasonable
to use these functions anyway. e. g. see the response by "maozhoulu"
on Jun 21, 2002.
I tried it in Sun Application Server Nine in my stateless Session Bean:
package RS;
import RS.CourseHome;
import RS.CoursePK;
import java.rmi.RemoteException;
import javax.naming.InitialContext;
import javax.naming.Context;
import javax.rmi.PortableRemoteObject;
import javax.ejb.EJBException;
import java.io.*;
public class AddCourseBean implements javax.ejb.SessionBean {
public void ejbCreate(){};
public void CreateCourse (int CourseNumber, String CourseName) {
try {
System.out.println("in Create Course");
PrintWriter F = null;
try {
F = new PrintWriter (new FileOutputStream("/tmp/v/af"));
catch (java.io.FileNotFoundException fe){}
F.println ("here zero");F.flush();
InitialContext jndiContext = new InitialContext();
F.println ("here one");F.flush();
Object o = jndiContext.lookup("ejb/X");
...I got a Null pointer exception on the line:
"F.println("here zero"); Is there anyway one can do simple debugging with print lines in one's beans?
Or is there something obviousthat I am overlooking? (I saw mention of doing
debugging with System.out.println but to where would the bean write?)
I tried using the Jakarta Commons Logging, but I got a
java.lang.NoClassDefFoundError on org/apache/commons/logging/LogFactory
Which logging system does one use in GlassFish, hopefully one with minimal
configuration? I want to do some debugging, not set up logging for a full
enterprise system.
Thanks for your insight and advice.
Dr. Laurence Leff, Associate Professor of Computer Science WIU ST447 61455
Pager 309 367 0787, Fax 309 298 2302My apology for posting this message twice. I looked for it before and
did not see it. I thought I forget to click the "Post message" button.
Also, I did resolve one problem. System.out.println does go to
the log file, which in my case turned out to be:
/opt/j2ee/SUNWappserver/domains/domain1/logs/server.log
(Obvously, the first part would vary based upon where you installed your
Application Server Nine.)
However, it would be nice if there was some way to use FILE I/O inside of
beans. I am teaching some J2EE in the graduate software engineering course,
and I believe this would be pedagogically sound even if other techniques
would be appropriate for a production environment.
Thanks for your patience with this problem and my duplicate post.
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