Spawning Threads inside the Web Container

What are the ramifications of a developer spawning off threads from a "helper"
object called from a servlet service() method ?
Thanks in advance.

That's what I said, it is not at all advisable but if you know what you
are doing it can work just fine.
The biggest issue is migration since the behavior is not defined in the
spec and thus all vendors can implement it differently and it can change
from version to version, which in turn defeats the J2EE portability
advantage.
That is why I highly recommended using JMX timers since it is going to
be available on all J2EE servers and then the only vendor dependent
thing is to get the MBeanServer.
Dejan
DN wrote:
Hello
I was also doing the same thing from my servlet but using another class which
extends thread.
I was using JDBC calls in the new thread , eventhough it worked fine I was getting
warning messages in the console when I was using WSAD.(websphere studio).
My app is deployed to WLS , i did not see any messages in WLS.
When I post this issue in a forum , some one advised me that it is not advisable
to open up threads from the servlets and this is what he said 'quote'
so eventually (i.e.
J2EE 1.4) spun threads from a Servlet accessing a
database outside of a transaction will not be
supported either.
"Deyan D. Bektchiev" <[email protected]> wrote:
Whit,
If you are not careful you can very well starve the JVM, lose your
security, transaction contexts and probably some other bad things I
don't know about...
But having said all those scary things, I must admit that we do it all
the time and don't have any issues with that.
For most purposes you should try to use the JMX timer service instead
of
spawning your own threads. You callback will be called in a different
thread from the Weblogic thread pool and I guess this will be sufficient
for most cases.
Regards,
Dejan
Whit Armstrong wrote:
What are the ramifications of a developer spawning off threads from
a "helper"
object called from a servlet service() method ?
Thanks in advance.

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hi,
do you use websphere? version?
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and check this
http://www-1.ibm.com/support/docview.wss?uid=swg21121449

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Valery Silaev
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Message was edited by: Bertram Ganz
This thread was branched from forum thread: How to print the data of a Model node.

Hi Valery,
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Thanks,

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Edited by: Eric Batzdorff on Jun 12, 2009 12:24 AM
Edited by: Eric Batzdorff on Jun 12, 2009 12:24 AM
Edited by: Eric Batzdorff on Jun 12, 2009 12:25 AM

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I ran into an interesting issue: I am spawning a thread inside
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thread uses some BMP entity beans to access some data from DB,
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<quote>
These networking functions are reserved for the EJB Container.
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<quote>
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Simon wrote:
I ran into an interesting issue: I am spawning a thread inside
my stateful session bean's ejbCreate(...) method. The spawned
thread runs in an infinite loop until some stop signal. The
thread uses some BMP entity beans to access some data from DB,
it creates some BMP entity beans as well as creates another
stateful session bean in each iteration. The application ran
into a crash. Now I have a couple questions:
- First, is it an allowed operation to have a stateful session
bean spawn off threads? Am I violating the specs?
- Second, is it also allowed to have that thread create another
bmp entity bean and another stateful session bean? Again, am I
violating the specs also in here?
Your responses will be very much appreciated.
- Simon

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"nit_vs" <[email protected]> wrote in
message
news:gi854o$qn5$[email protected]..
> Hi,
> I have an HBox with roundedRectangle skin inside a
repeater in a
> vertical
> layout. HBox has drop shadow filter applied on it.
Problem is that, as
> repeater
> is executing the drop shadow is getting hid by next HBox
created below the
> previous Hbox. I want the shadow on the top of next
HBox.
> Code Snippet:
> <mx:Repeater id="myrep" dataProvider="{myAC}">
> <mx:HBox borderSkin="RoundedRectangle"
backgroundColor="0xB9C3C9"
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height="80"
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> <mx:filters>
> <mx:DropShadowFilter distance="14" angle="45"
blurX="10" />
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> </mx:HBox>
> </mx:Repeater>
> Any way to solve it?
>
Draw them from the bottom up, or change the childIndex of
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Exact functions of Servlet context and servlet Config inside web container

What is the correct(exact) function in the Servlet Context and Servlet Config inside the Web Container?.
Pls anybody response me.
-- Palani

ServletConfig:
The container reads the servlet init-parameters specified in web.xml then adds them to ServletConfig. The container then passes ServletConfig to the servlet. Thereafter, the servlet can access the ServletConfig and get the servlet init-parameters. The idea is that you can avoid hard coding data that might change in your servlet code, e.g. an email address. If the email address changes, you can change it in web.xml instead of having to hunt through all your code and change the email address every place it appears and then recompiling the servlet.
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palanithendral wrote:
What is the correct(exact) function in the Servlet Context and Servlet Config inside the Web Container?.
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Message was edited by: Raja Nasrallah

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Trouble compiling java files inside the packages.

Hello I have a question in Java when compiling with packages. Can anyone Help??
My 2 java files BeerSelect2.java & BeerExpert.java are in packages com.example.web & com.example.model respectively.
C:\MyProjects\beerV1\src\com\example\web\BeerSelect2.java
and
C:\MyProjects\beerV1\src\com\example\model\BeerExpert.java
I have compiled the BeerExpert.java in the model package.(ie the class file for BeerExpert is in the com.example.model package.)
My BeerSelect2 file which is inside the web folder is like this
package com.example.web;
import com.example.model.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
public class BeerSelect2 extends HttpServlet
public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
response.setContentType("text/html");
PrintWriter out=response.getWriter();
out.println("Beer Selection Advice ");
String c=request.getParameter("color");
out.println(" Got Beer color "+c);
BeerExpert be=new BeerExpert();
List result=be.getBrands(c);
response.setContentType("text/html");
out.println("BEER SELECTION ADVICE ");
Iterator it=result.iterator();
while(it.hasNext())
out.print(" try: "+it.next());
This shows 3 comile errors.
& the BeerExpert.java file which is in the model folder is like this:
package com.example.model;
import java.util.*;
public class BeerExpert
public List getBrands(String color)
List brands=new ArrayList();
if(color.equals("amber"))
brands.add("Jack Amber");
brands.add("Red Moose");
else
brands.add("Jale pale Ale");
brands.add("Gout Stout");
return (brands);
This compiles fine in the model folder.
Now when I'm trying to compile my BeerSelect2.java in the 'web' folder in which I'm trying to import the com.example.model.* which is as follows
C:\MyProjects\beerV1\src\com\example\web>javac BeerSelect2.java
which gives 3 errors like this
BeerSelect2.java:3: package com.example.model does not exist
import com.example.model.*
^
BeerSelect2.java:22:cannot find symbol
symbol: class BeerExpert
location: class com.example.web.BeerSelect2.
BeerExpert be=new BeerExpert();
^
BeerSelect2.java:22:cannot find symbol
symbol: class BeerExpert
location: class com.example.web.BeerSelect2.
BeerExpert be=new BeerExpert();
^
Can anyone help???

Since the classes are part of the com.example.web and com.example.model packages the most straight forward way to compile is from the folder containing "com". Assuming you want the resulting .class files to be in the same folders are their associated .java source files:
C:\MyProjects\beerV1\src\> javac -cp . com\example\model\BeerExpert.java
C:\MyProjects\beerV1\src\> javac -cp . com\example\web\BeerSelect2.javaThe -cp . part is there to set the classpath (the location that the compiler will use to locate java classes) and thereby let the compiler make sense of the import statements.
The presence of "src" in the directory path strongly suggests, however, that the intention is not to have source and class files end up in the same directory. If this is the case read up on the syntax of the http://download.oracle.com/javase/6/docs/technotes/tools/windows/java.html (java.exe) and http://download.oracle.com/javase/6/docs/technotes/tools/windows/javac.html (javac.exe) commands. (paying attention to how searching for types is done). Also read up on any documentation you were given for building the application (if you are modifying something already given).
If you are using an IDE you should say.

Spawning Threads inside the Web Container

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