Archive

Archive for July, 2007

An attempt was made to create a named consumer (name) on a connection with no clientID

July 31st, 2007 Arun Manivannan No comments

While creating a DurableSubscriber please do specify the client id before specifying a named consumer. Please have a look at the small code i wrote. Do remember to set the ClientID before creating a session from it. The clientID becomes null and immutable after the session is created. Also remember to give the same client id while creating a DurableSubscriber.

ClientID

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Categories: Uncategorized Tags: ,

Configure JMS Server in Weblogic 9.2 — Pub Sub

July 31st, 2007 Arun Manivannan No comments

Following yesterday’s sample code i wrote for P2P, here is an example code and configuration procedure of Topics in Weblogic 9.2. I have tried my best to do justice to the PDF I have created. Please go through and revert if i need to make some corrections.

Find the PDF here

And the code here. Publisher.java and Subscriber.java

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First time in my net life. Google goes down…

July 31st, 2007 Arun Manivannan No comments

Time is in IST

Google search page

orkut.JPG

Gmail

On the other hand, at the same timestamp, look at my del.icio.us.

delicious

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Categories: Uncategorized Tags: ,

Configure JMS Server in Weblogic 9.2

July 31st, 2007 Arun Manivannan 3 comments

I did this homework today. Just wanted to share it with you. I have uploaded the JMS Sender and the Receiver files and the JMS server in Weblogic 9.2 configuration procedure in a separate pdf file. You can find these files HERE

As for others who has reached this page after getting a NameNotFoundException — Unable to resolve destination queue, what you have to do is to configure a JMS server under Services –> Messaging and make your DestinationQueue (configured under SystemModule) a subdeployment of the JMSServer. Details of configuring is in the above mentioned PDF.

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Abstract Class inside an Interface??? Interface inside an Abstract class???

July 31st, 2007 Arun Manivannan No comments

Interface inside an abstract class is static.


package com.nu;

public abstract class ClassInterface {

public interface Intrface{

public void m1();

}

}
And so is an Abstract class inside an interface

package com.nu;

public interface IntrfaceClass {

public abstract class AbstrClass{

public void m1(){


System.out.println("from m1");

}

}

}
Usage :

package com.nu;

public class ImplClass extends IntrfaceClass.AbstrClass implements ClassInterface.Intrface{

public static void main(String[] args) {

}

}

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USER_SOURCE — View the source SQL of your Procedure, Type in Oracle

July 14th, 2007 Arun Manivannan No comments

Yesterday i came across this particular system table USER_SOURCE.  Gives the source SQL for a variety of Oracle objects including Procedures and Types.  I dont have oracle installed in my home. So no screenshots.

You would have already known that USER_VIEWS table will give you the source select statement of a VIEW.

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Categories: user_source, user_views Tags: ,

Merrill Lynch interview questions

July 13th, 2007 Arun Manivannan 1 comment

I am not sure how my previous post got deleted.  Let me tell you something before you go through the questions.  I had three tests and three tech rounds (actually speaking).  Most of the questions were just questions from my answers.  So, basically you drive the interview. Trust me, the interviewers are damn good in what they are doing.  Frankly, I never have faced anything like this before.  They asked a lot many questions but these are all i could recollect.  If not for Merrill Lynch, these questions will surely be helpful for you for some other company.

1) Table level and row level lock

2) How to force a row level lock in a select query (for update clause)

3) Explicit locking in oracle (NO)

4) Deadlock

5) Shared and Exclusive Lock

6) Difference between wait and sleep (the timout seconds as arguments)

7) static synchronized methods possible? YES
8) What do they mean? What does static synchronized methods lock? (locks java.lang.Class)

9) Is it possible for two threads to get into a same class if one of the methods is static synchronized and the other just synchronized?

10) Configure webservices (Axis) in weblogic

11) What is a multipool

12) Difference between Topic and Queue. How to identify packet loss in a Topic publishing?

13) XSLT, XSR? ( I have never heard of XSR)

14) DTD and XSD difference.

15) Why is there just one datatype called CDATA in DTD?

16) Difference between Complex and Simple datatype in XSD

17) How to validate an XML?

18) How to disable XML Validation in runtime when the XSD specified in the processing instruction (residing in a different machine) is not available

19) DOM and SAX difference.

20) Apache POI API (just because I had this on my resume)

21) >>> An Abstract class is an interface?

>>> An interface is an abstract class?

22) What is Rowid? Can we update the column?

23) What is TRANSACTION_SERIALIZABLE?

24) How to make an IO operation thread safe (use wait/notify model or use Java NIO)

25) Rules of Serialization

26) How to set security manager in a remote machine

27) What is a sandbox?

28) How to copy serialized contents from one object to another? (Use reflection??)

29) What is a JMS Exception?

30) How to create transaction ? (User Transaction or use EJBs)

31) Methods in javax.jta.UserTransaction

32) How to rollback a transaction in an EJB ? context.setRollbackOnly()

33) When does EJB automatically rollback transactions (When a SystemException is thrown)

34) What is twophase commit?

35) In a distributed transaction what is the requirement from the JDBC Driver Class (should be XA)

36) Is XA possible in all databases?

37) Are you contributing to Apache?

38) What projects in Apache have you used?

39) Business Delegate resides on the server-side? (One machine holding the web-tier and the another machine holding EJB-tier. Where will you place the BD?)

40) Role of a Service locator apart from lookups ? (Cache Home objects)

41) In a stateless session bean, there is no difference among Remote Objects. Why cant we cache the Remote Objects too? (????!!!)

42) Pattern of Home Objects in EJB (Proxy)

43) Difference between TIBCO and MQ based messaging model ? (Who knows)

44) What is stack overflow ? (Too many methods in a stack. Often comes in a uncontrolled recursive function)

45) How to increase the stack memory (I don’t know)

46) Increase the heap memory (Xmx and Xms)

47) Can we have a nested transaction? (Not in J2ee)

48) How to have a count of EJB users for a stateless session bean at any time (Remember ejbCreate gets called only once. After creation of the bean, the bean goes to the pool. EjbCreate doesn’t get called the second time)

49) How to link MDBs with Queue?

50) What is the need to have a QueueManager?

51) What gets returned ? (20)

public int m1(){

try{

return 10;

}

catch (Exception e){

}

finally{

return 20;

}

}

52) Why use Ajax?

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