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Re: Performance issue

Leon Rosenberg

2007-01-04

Replies:

Hmm,
can you send some code?

What kind of validation do you use? Serverside or js?
I suppose it happens because the validation-whatsoever send the user
directly to use jsp bypassing the action.

If you need a quick and dirty solution, alter you preExecute method to
put the objects into the session instead of the request scope. If you
want to make it less dirty add a check whether they already are there:
if (req.getSession().getAttribute("objHospitals")==null)
req.getSession.setAttribute("objHospitals", staticObjHospitalsVariable);

For the proper solution you should show your code and struts-config
parts, so we can work out the best solution.

regards
Leon

P.S. are you on struts 1.x or 2.x?

On 1/4/07, Daniel Chacón Sánchez <danielccss@(protected):
> Leon!!! something happen... I applied your solution putting the objects in
> the request in the preExecute method of the base action, and all works
> fine, but... when the user made a mistake, for example leave a required
> field in blank, and the ActionErrors validate method of the ActionForm
> return the errors, the jsp launch the following exception:
>
> javax.servlet.jsp.JspException:
>        Cannot find bean under name objHospitals
>
> This only happen when the method validate of the actionErrors returns an
> error, why the request is lost or why the jsp don´t found the object? How
> can I solve this problem, thanks!!! Hope you can answer Leon
>
>
> 2007/1/2, Leon Rosenberg <rosenberg.leon@(protected)>:
> >
> > u welcome :-)
> > L
> >
> > On 1/2/07, Daniel Chacón Sánchez <danielccss@(protected):
> > > Thanks Leon!!!, I got it!!!
> > >
> > > 2007/1/2, Leon Rosenberg < rosenberg.leon@(protected)>:
> > > >
> > > > On 1/2/07, Daniel Chacón Sánchez <danielccss@(protected):
> > > > > Thanks
> > > > >
> > > > > Leon, about using the servlet context, I read that on a distributed
> > > > > application the share information of the servlet context is not
> > > > entererly
> > > > > global right?:
> > > >
> > > > Right, but since the data is readonly its ok to have a copy per
> > > > webserver, right? It doesn't harm you to put one data-object (even a
> > > > complex one) in the application scope. If you need to check for
> > > > updates periodically you could make use of the subject-observer
> > > > pattern and notify the webservers from the business layer via
> > > > rmi/corba/jms/whatever to renew their data or just check if the data
> > > > is still valid and replace it if needed periodically in a separate
> > > > daemon thread.
> > > >
> > > > >
> > > > > *"...In the case of a web application marked "distributed" in its
> > > > deployment
> > > > > descriptor, there will be one context instance for each virtual
> > machine.
> > > > In
> > > > > this situation, the context cannot be used as a location to share
> > global
> > > > > information (because the information won't be truly global). Use an
> > > > external
> > > > > resource like a database instead."*
> > > > >
> > > > >
> > > > > About the second solution that you gave to me, I do not understand,
> > you
> > > > said
> > > > > that for example in my BaseAction Class create a method to put the
> > > > objects
> > > > > in the request? The problem is that in every request the application
> > > > will go
> > > > > to the database to load the objects and then put them on the
> > request!
> > > > What I
> > > > > do not understand is how to put the objects in the request without
> > have
> > > > to
> > > > > go the database each time that a request is made and the method in
> > the
> > > > > BaseAction is call.
> > > >
> > > > BaseAction extends Action{
> > > >  private static Data1Class data1;
> > > >  private static Data2Class data2;
> > > >  ....
> > > >
> > > >  static{
> > > >    data1 = createData1FromDB();
> > > >    data2 = createData2FromDB();
> > > >  }
> > > >
> > > >  //now in my actions i have my own execute method, you may have
> > > > something //similar:
> > > >      protected void preProcessExecute(
> > > >                 ActionMapping mapping,
> > > >                 ActionForm af,
> > > >                 HttpServletRequest req,
> > > >                 HttpServletResponse res)
> > > >                 throws Exception{
> > > >
> > > >           req.setAttribute("data1", data1);
> > > >           req.setAttribute("data2", data2);
> > > >          .........
> > > >     }
> > > >
> > > >      protected void postProcessExecute(
> > > >                 ActionMapping mapping,
> > > >                 ActionForm af,
> > > >                 HttpServletRequest req,
> > > >                 HttpServletResponse res)
> > > >                 throws Exception{
> > > >
> > > >      }
> > > >
> > > >      public abstract ActionForward myExecute(
> > > >           ActionMapping mapping,
> > > >           ActionForm af,
> > > >           HttpServletRequest req,
> > > >           HttpServletResponse res)
> > > >           throws Exception;
> > > >
> > > >
> > > >      public final ActionForward execute(
> > > >           ActionMapping mapping,
> > > >           ActionForm bean,
> > > >           HttpServletRequest req,
> > > >           HttpServletResponse res)
> > > >           throws Exception {
> > > >
> > > >
> > > >           preProcessExecute(mapping, bean, req, res);
> > > >           ActionForward forward = myExecute(mapping, bean, req,
> > > > res);
> > > >           postProcessExecute(mapping, bean, req, res);
> > > >           return forward;
> > > >      }
> > > > }
> > > >
> > > > You just have to ensure, that when an Action overwrites preProcess it
> > > > calls super.preProcess.
> > > > The advantage of this method is, that actions at the end of the
> > > > hierarchy have a chance to overwrite the data by the base action,
> > > > which is quite useful for internationalization and such.
> > > >
> > > > Same rules for updates as for servletContext apply.
> > > >
> > > > regards
> > > > Leon
> > > >
> > > >
> > > > >
> > > > > 2007/1/2, Leon Rosenberg <rosenberg.leon@(protected) >:
> > > > > >
> > > > > > The easiest way is to initialize the data once in the
> > > > > > init(ServletConfig) method of the servlet and put them into the
> > > > > > application scope (servletcontext). The struts tags will be able
> > to
> > > > > > access the data directly, so you don't need to change a bit.
> > > > > > Of course the data structures theirself must be threadsafe to
> > access,
> > > > > > which shouldn't be a problem if you are only reading them.
> > > > > >
> > > > > > Alternatively you can perform this in a static initializer in a
> > action
> > > > > > and put them in the request scope of each request (if you have a
> > > > > > common code block all actions are passing through, like
> > authorization)
> > > > > > or into the application scope on first request (which would need a
> > bit
> > > > > > of synchronization with double checked locking)
> > > > > >
> > > > > > regards
> > > > > > leon
> > > > > >
> > > > > > On 1/2/07, Daniel Chacón Sánchez <danielccss@(protected):
> > > > > > > Hi all, I'm using struts framework on my application, but I have
> > a
> > > > > > > perfomance question.
> > > > > > >
> > > > > > > When my application starts I load objects in session that may or
> > may
> > > > not
> > > > > > > will be used (depends on what the user does), for example I
> > load
> > > > the
> > > > > > health
> > > > > > > centers, hospitals, countries, etc, that will be available for
> > the
> > > > users
> > > > > > in
> > > > > > > html:selects, I know that to had many objects in session is not
> > > > good, in
> > > > > > > fact each time the user click on one application option (menu)
> > all
> > > > the
> > > > > > > objects in session are erased, except the ones that I load on
> > the
> > > > start
> > > > > > of
> > > > > > > the application. Is there a way (maybe a pattern) to load this
> > > > objects
> > > > > > in
> > > > > > > the moment that are needed, and not load all at the start of the
> >
> > > > > > > application. This object are use on differents modules so I load
> > > > them on
> > > > > > the
> > > > > > > start of the aplication and put them in sesion for not to go to
> > the
> > > > > > database
> > > > > > > each time I need to load them on a html:select.
> > > > > > >
> > > > > > > any solution, idea? or that is the only way?
> > > > > > >
> > > > > > >
> > > > > >
> > > > > >
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