Javabeans and concurrency

Javabeans use instance variables that represent the bean's properties with
          getter and setter methods. Are the bean's properties thread safe?
          If I create a bean and store it in a session, can I assume when I do a
          getter/setter on the property that there will not be concurrency issues? (I
          realize that session objects have issues with frames but I can ignore that
          for now).
          Any examples I have seen of using javabeans with JSP's do not use
          single-threaded and do not synchronize access.
          thanks.

Actually, we've just seen a case where a session scope bean
          was getting accessed concurrently by different threads, coming
          from a single browser window. We are using the Apache-Weblogic
          plugin, which at times will cause a failover retry on the same
          server on behalf of the same session, and so the same session
          scope bean will be used. Problem is, the failover retry should
          not have happened, since the server hadn't really failed, it was
          just taking a long time. This, I would think, is a bug in the
          Apache-Weblogic plugin mechanism.
          Anyway, the second retry attempt causes a new thread to
          assume the pre-existing session scope objects, which has
          to be a problem, in my book...
          Jason
          "WebLogic" <[email protected]> wrote in message
          news:[email protected]...
          > This is accurate except that in the session case, it is
          > really per set of browser windows. You can see concurrency
          > problems when more than one browser window is open
          > or when you use frames and share the JavaBeans in the
          > session.
          >
          > Sam
          >
          > "sumanth" <[email protected]> wrote in message
          > news:[email protected]...
          > > well it depends on the scope of the java bean.
          > > normally there are 3 sometimes 4 scope's for the beans
          > > page,request,session,application.
          > >
          > > the first 3 you will not run into any problem's as they
          > > are on a per page,per request,per user respectively.
          > > It is only when you use the bean as an application scope u
          > > should make sure that they do not have any instance variables ,
          > > if they have u should handle the synchronization.
          > >
          > > the above discussion is for beans.
          > >
          > > talking about jsp's in general...
          > > if you have any variables declared in the <%! %> (note the !)
          > > they are not thread safe as they are class variables. all jsp's by
          default
          > > DO NOT implement the singleThread Model (performance) but one can
          > > have thier jsp's implement the single thread model by having this
          > directive
          > > on the top of the page
          > > <%@page isThreadSafe="false" %>
          > >
          > > -Sumanth
          > > "JOG" <[email protected]> wrote in message
          > > news:[email protected]...
          > > > Javabeans use instance variables that represent the bean's properties
          > with
          > > > getter and setter methods. Are the bean's properties thread safe?
          > > > If I create a bean and store it in a session, can I assume when I do a
          > > > getter/setter on the property that there will not be concurrency
          issues?
          > > (I
          > > > realize that session objects have issues with frames but I can ignore
          > that
          > > > for now).
          > > >
          > > > Any examples I have seen of using javabeans with JSP's do not use
          > > > single-threaded and do not synchronize access.
          > > > thanks.
          > > >
          > > >
          > >
          >
          >

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hi!
what is the diffrence between a javabean and entreprise jvaabeans! i mean which are the uitilization featires of eaxh one !

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let me explain mor ethe suitation , in fact what i am loking for is to use javabeans to grant my application much more consistence and pertinence : si i am asking if it could be possible to use javabeans in my case especially if i am not trying to developp a web application but a cleint /server one allowing some services.
The application is in fact dealing with a stock exchange market and what i am trying to do is to grant particilar registrated customers to have the informations that they need ( portofolio, currency's status, market indicators, .) also drawing some charts decribing rates, variations, and others specefic financial caracterestics .So , if we consider that this application is not a web application ( no HTTP request and no servers like apache or others ) how it is possible to use javabeans and not EJB to build the application? i mean what could be suitable and preferable to rely on and dvelop to ensure a good java application !!
if you need more details to help you find the answer for me don't hesitate to answer me back !!
Someone here gave me that answer
use RMI to code the services and (Updateable) Value Objects to pass the information between tiers.
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for now i found some problem with 'javabean' used in jsp.
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thanks!

javabeans are standard classes but have :
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why don't directly use attributes ?
look this thread :
http://forum.java.sun.com/thread.jsp?forum=45&thread=314643
this is one, but it's not the only, reason.
Regards.

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Why not simply code them by hand using the beans' documentation? You'll actually learn something instead puzzling over the myriad shortcomings associated with GUI builders.
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Weak and concurrent hash map for caching

Hello,
I have written a very simple cache class with both weakness and concurrency benefits. This class is intended to be used as a weak cache in "hot redeploy" capable servers (JBoss or any other).
My implementation uses the (problematic) "double-check" pattern with a reentrant lock and encapsulates a WeakHashMap with WeakReference values (to avoid circular key/value references). Here is the code:
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Message was edited by:
fwolff999

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http://apmblog.dynatrace.com/2010/03/18/how-to-avoid-the-top-5-sharepoint-performance-mistakes/
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Please remember to mark the replies as answers if they help, and unmark the answers if they provide no help. If you have feedback for TechNet Support, contact
[email protected]

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Javabeans and concurrency

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