Sajid Moinuddin

Hello all,
Please look at the given codes. Can anyone explain why the output is different? I know it has something to do with dynamic/ static binding. But can anyone please explain a bit. Doesn't it violates the core polymorphism principle? I thought Java is a OO language !


class A{ } class B extends A{}; class C extends A{}; class D extends B{}; class E extends C{}; public class Overloading { public void m(Object a) { System.out.println("Object: "+a.getClass()); } public void m(A a) { System.out.println("A:"+a.getClass()); } public void m(B a) { System.out.println("B:"+a.getClass()); } public void m(C a) { System.out.println("C:"+a.getClass()); } public void m(D a) { System.out.println("D:"+a.getClass()); } public void m(E a) { System.out.println("E:"+a.getClass()); } /** * @param args */ public static void main(String[] args) { Overloading ov = new Overloading(); A d1 = new D(); D d2 = new D(); ov.m(d1); ov.m(d2); } }

output:
A:class D
D:class D

Regards,
Sajid.

Hi all,
We have developed an web based application on a single jboss server. We have stateful session bean/ stateless session bean/ entity beans. However, Since all the clients of ejb are in the same container, we have implemented the whole module using local interface. None of our components so far has remote interface. Now, we want to cluster the system. bypassing the ejb clustering/stateful session bean clustering is not an option for us.
Now, My question is can we cluster the whole system with the local interfaces so far we have used? We want session state replication of stateful session beans. I want to understand the whole picture before rushing into any perticular solution. any help will be much appriciated.
Regards,
Sajid.

Hello guys,
I have been working for USA based large scale offshore products for the last two years. I am a SCJP(92%), SCBCD (98%) and I have extensive experience of working with technologies like servlets, jsp, ftl , spring, hibernate, ejb, jboss etc. Just recently I am thinking about taking some extra work since I have enough time besides my job.I would like to work with product based team where I can build framework/software module/ejb component etc.I would like to hear your experience on freelance projects available on web. What do you think? Where should I start? I would really like to know some good link where I can start. Your advice has always been helpful to me. So please feel free to add any advice.
Regards,
Sajid.

I am assuming you studied like 4 month since you started working on your project for this exam right?
...Well, not exactly. I was given the responsibility of designing & coding the ejb layer of our application. Since there was no other ejb developer around [I am the only one working on the ejb layer]and I had no prior experience in ejb...I thought I learnt java by sitting for scjp, why not sit for scjd so i can learn some ejb. So, I started preparing for the exam to be confident about the project i'm doing.
And about the difficulty level of the exam, it was almost the same as the one in HFEJB. If you really want to know, I would say it was a bit easier. 70% questions were sure thing, 15-20% were questions with medium difficulty level. But I guess 5-6 questions were really tricky. I would have got them wrong if I was not working on EJB.

Regards,
Sajid

Hello guys,
Last week I cleared the exam with 98%. Missed 100% for a silly security question . However, thanks to HFEJB and Javaranch. You guys are really the best.
About the exam, 10-15% questions were a bit tricky. I was working on a 1 member ejb project for last 4 months. Thats why I think many things were easy for me. Don't know how it would have been otherwise. I was using jboss for my app server. Actually jboss violates many rules of the specs. So to be sure I used to go through the ejb spec frequently. But using jboss instead of sun RI was fun because I could develop and deploy applications rapidly. I didn't have to put too much effort preparing for the exam because I had to study a lot for my project and that was good enough to prepare me for the exam.
I didn't make my own notes. Thanks to (https://coderanch.com/t/160253/java-EJB-SCBCD/certification/Study-NotesGiju) & Java Black Belt. I didn't do a lot of mocks. Just the ones of JDiscuss, ejbcertificates and HFEJB. But from the very beginning , I was very careful to spot my weekness and tried to recover them. I think It is very important to try the mocks and find out in which area you can improve.
I feel really great passing the exam and I encourage others to take it. It will strengthen your confidence and be very helpful for your design decisions. I don�t know how much it will help you to find a job though�I�ll see that in future and let you know� .
Regards,
Sajid

Hello all,
I am running a bulk operation in a single transaction.[adding 10000 cmp entity beans].

When I start up the server, the operation runs just fine...Even I can do the same operation for 3-4 times...But after some time, I start getting
the following kind of exception saying transaction not active. I'm sure its' not a problem of transaction time out of transaction manager. In that case, the operation would never have succeeded when the server started. My guess is, my early operations are messing up the database connections or using up some sort of resouce So my later operations fails. I am very near to my deadline and suddenly this problem started. Any one please help. I am stuck in the middle of nowhere.


SQL: SELECT max( t0_x.componentId) FROM ClientTemplateElement t0_x 2006-07-30 13:54:32,933 ERROR [org.jboss.ejb.plugins.cmp.jdbc.JDBCEJBQLQuery.ClientTemplateElement#e jbSelectMaxPk] Find failed org.jboss.util.NestedSQLException: Transaction is not active: tx=TransactionImple < ac, BasicAction: 7f000001:80a2:44cc58c3:707e status: 4 >; - nested throwable: (javax.resource.ResourceException: Transaction is not active: tx=TransactionIm ple < ac, BasicAction: 7f000001:80a2:44cc58c3:707e status: 4 > :wink: at org.jboss.resource.adapter.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:79 ) at org.jboss.ejb.plugins.cmp.jdbc.JDBCAbstractQueryCommand.execute(JDBCAbstractQueryCommand. java:210) at org.jboss.ejb.plugins.cmp.jdbc.JDBCAbstractQueryCommand.execute(JDBCAbstractQueryCommand. java:128) at org.jboss.ejb.plugins.cmp.jdbc.bridge.JDBCSelectorBridge.execute(JDBCSelectorBridge.java: 99) at org.jboss.ejb.plugins.cmp.jdbc.bridge.JDBCSelectorBridge.invoke(JDBCSelectorBridge.java:7 0) at org.jboss.ejb.plugins.cmp.bridge.EntityBridgeInvocationHandler.invoke(EntityBridgeInvocat ionHandler.java:91) at org.jboss.proxy.compiler.Runtime.invoke(Runtime.java:62)







regards,
Sajid

Anyone...please help...my exam is knocking on the door.....
sajid

Which DB are you using?...i faced a similar kind of problem caused by the db which didn't support transaction.

PS: what are the valid method argument for a finder / select method? is Date a valid argument??
Sajid

Hi there,
My exam is knocking on the door and i have some doubt about ejbql.

1) Can ejbSelect<METHOD> return cmr fields / collection of it?
2) Can ejbSelect<METHOD> return an Enitity Object/collection of it which is not related to the entity bean for which the select method is defined?

3) Can ejbSelect<METHOD> return cmp field of an Enitity Object/collection of it which is not related to the entity bean for which the select method is defined?

I didn't find much in Cathys book. Can anyone please tell me the points i need to be careful about?
Sajid

Is there a JDK1.5 installation bundle which I could just untar/unzip and run??

What if I copy the contents of jdk home to a new machine? will it work??
sajid

I know the bean is not accessed concurrently. But the container is not supposed to be intelligent enough to know that...if it finds calls to the same bean reentranly within the same transaction, concurrent or not, it should throw exception.

Bean A(entity with id 10) calls a method of bean B(entity with id 20)...Bean B looks up bean C(stateless session) and calls a method on it. Bean C calls bean A(entity with id 10)... now is this reentrant??
Mind it that Bean a doesn't pass it's component interface to bean B.
In jboss it runs well without reentrancy ...But is that legal?
regards,
Sajid

So, What's the conclusion? I can't use a long/int/double as my pk? I have to use Long/Integer/Double??

Hello all,
Can anyone give me any way/link to automate the deployment process in RI? Coming from the jboss world where I am used to call "ant deploy-ejb" to do all the compile, make jar & deploy(all i have to give is a proper jboss.xml with only the real jndi names)....i'm really annoyed by the deployment process of RI(Open the deployer, generate sql and bla bla bla). But jboss violates many specification, so I can't rely on it to prepare for SCBCD...but the pain of deploying an application in RI is so huge that I am scared to go to RI to verify a concept....May be there is a better way of doing this which i am missing. Can anyone help?
regards,
Sajid