Lingan Rajan

Paul
Thanks for the answer.
By "Operating System Call" what I actually mean is the scenario where the implementation of JVM instruction set is calling/delegating to the hardware instruction. So I would like to know if there are JVM instructions that are totally independent of the hardware instructions.


Thanks
Lingan

I am trying to understand the basics of JVM.
I undersntand that JVM has its own set of instruction set and they are interpreted during runtime by the JVM.
During interpratation of opcodes does each of the them result in operating system call ?
In other words as JVM interprets ,is each interpratation just delegated to the underlying OS ?
I think the delegation to OS happens only when necessary , like opening a socket .
So JVM should be able to handle some functionality even without delgating to the OS at all.
Please let me know if my understanding is right.

Thanks
Lingan

Michal
I am not an expert with performance but here are my thouhghts.
The StringBuilder initialization should certainly help.
Apart from that the screen shots show lots of Object[] and String . Have you inspected the stack trace of those Objects ?
Also how about caching certain strings that are repeatedly used ? like the HTML elements .

Hello All
I did go through articles on Virtual Machines and Interpretation/Compiled languages.
I will greatly appreciate if some one can give me a clarification on the below and verify if my understanding is right.

1. Java Virtual Machines have instruction sets of their own.
During normal interpretation these instruction sets are used to execute the statements.
Byte codes are not compiled to the machine code in this scenario

2. During JIT compilation parts of the code are compiled to machine code.
In this case the JVM instruction sets are not used at all.

Thanks
Lingan

I went through the JVM spec , still could not get that clarified.
Could you give me a explanation or point to some links ?

Thanks.

Thanks for answering that part.

So I think 'interpreted' actually means that the byte code are being compiled to machine code right ?

In case of a stand alone program run with JVM without JIT , are all the classes's byte code interpreted to machine code in one shot and then executed line by line ?

Ok .

I understand that JIT converts the byte code to native code only when the particular piece of code is executed.
Now in this context , when it is said that the interpretation happens one at a time , is it like each of line of code is interpreted one by one ? then to me it is almost like JIT . I know this cant be the case hence my question.

Thanks
Lingan

Hello All

I am newbie as far as Java Performance topic is concerned.
I came across the below lines as I was going through an article and trying to understand it.
Here are the question that I have . Any help is highly appreciated.

"The original JVMs interpreted bytecodes one at a time. Second-generation JVMs added a JIT compiler, which compiles each method to native code upon first execution, then executes the native code"

1. 'JVMs interpreted bytecodes' , will this mean that the byte code is never converted to machine language ? what does 'interpreted' actually mean ?

2. 'JVMs interpreted bytecodes one at a time', what does 'one at a time' mean ?

Any help is highly appreciated.
Lingan.

Hello Ganesan
I would like to know if there are repetition of questions in the 787 Mock exams ?

Thanks
Lingan

Hi Jai
Here is the code and configuration
QueueConnection cnn = null; QueueSender sender = null; QueueSession session = null; Properties props=new Properties(); props.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory"); props.put(Context.PROVIDER_URL, "jnp://localhost:1099"); props.put(Context.URL_PKG_PREFIXES, "org.jboss.naming:org.jnp.interfaces"); System.out.println("Properties ok"); Context ctx=new InitialContext(props); Queue queue = (Queue) ctx.lookup("SampleQueue"); QueueConnectionFactory factory = (QueueConnectionFactory) ctx.lookup("ConnectionFactory"); cnn = factory.createQueueConnection(); session = cnn.createQueueSession(false, QueueSession.AUTO_ACKNOWLEDGE); TextMessage msg = session.createTextMessage("Hello World"); sender = session.createSender(queue); sender.send(msg); System.out.println("Message sent successfully to queue.");

Queue Summary :
General Properties
Name: jms.queue.SampleQueue
Version: a JMS Queue
Description: --

Traits
Name: SampleQueue
JNDI Binding: SampleQueue
Address: jms.queue.SampleQueue
Temporary: false
Paused: false

I did not add any Roles to the Queue while configuring.

Stacktrace
Exception in thread "main" javax.jms.JMSSecurityException: Unable to validate user: null for check type SEND for address jms.queue.SampleQueue at org.hornetq.core.protocol.core.impl.ChannelImpl.sendBlocking(ChannelImpl.java:287) at org.hornetq.core.client.impl.ClientProducerImpl.doSend(ClientProducerImpl.java:285) at org.hornetq.core.client.impl.ClientProducerImpl.send(ClientProducerImpl.java:139) at org.hornetq.jms.client.HornetQMessageProducer.doSend(HornetQMessageProducer.java:451) at org.hornetq.jms.client.HornetQMessageProducer.send(HornetQMessageProducer.java:199) at test.MDBCLient.main(MDBCLient.java:36) Caused by: HornetQException[errorCode=105 message=Unable to validate user: null for check type SEND for address jms.queue.SampleQueue] ... 6 more

Thanks
Lingan

Hi
I have deployed a MDB (java 5) in Jboss6.0 and am trying to invoke it by posting a message to the Queue from a stand alone program that runs outside the container. When I created the queue I did not attach any roles to the Queue. But the standalone program is not able to post the message as the container tries to authenticate the user. I have not set any user credentials in the stand alone program.
Can someone let me know how to turn off the security ? or how to get around this issue ?

Thanks.
Lingan

Hi
If a container is going to be up during the testing then you could as well have a simple servlet that will be return a hard coded SOAP response.
The caller of webservice will invoke the webservice with no change.

Lingan.

Hello All
I would like to know if it is possible to configure a interceptor on the EJB Client side .
I googled and it seems Jboss does allow this but it was not usefull as it did not have a lot of information and more over I am using websphere.

Thanks in advance.

Ivan

Thanks for the response. That helps.

Lingan.

Suri
The only think I can think of is to have a handler , identify the client and apply some sort of JAXB or XSLT or Regex transformation to the incoming soap request.

Lingan.