Thanks again Leon :)

2007/1/4, Leon Rosenberg <rosenberg.leon@(protected)>:
>
> there are 4 scopes or visibilities/lifecycles of attributes in the
> servlet/jsp world.
>
> page : the jsp page, same as local variable in a class.
> request: the duration of the request over multiple pages
> session: the duration of the user session, over multiple requests
> application scope: the whole webapp.
>
> However, talking about one of these scopes, you are always talking
> about _one_ server and _one_ webapp.
>
> So the application scope is something which belong to a) webapp and b)
> server in first line.
>
> As for multi-server environment - there are a lot of details here, and
> I don't really know whether yours handle application scope like a
> cluster-scope or not.
> I would assume that each server has its own copy created at the start
> of the server / deployment of the application.
>
> In my world, if I'd have to implement this requirement I would select
> one of two choices:
>
> In both: Create a service which manages the data and speaks to the db.
>
> Option 1. A thread in the application (or timer event, or scheduler)
> checks periodically (depending on the requirements it could be 1
> minute or 15) with the service whether the local data is still
> up-to-date. This can be done by comparing version numbers or creation
> timestamps. If not the data in the application scope gets replaced.
>
> Option 2. Service distributes new versions of the data via some
> publisher/subscriber mechanism, like JMS, CORBA
> Event/NotificationService, or something you develop yourself. The
> subscriber resides in the webserver and puts updated data into the
> local application scope.
>
> Option 3. You may also use whatever capabilities your environment has,
> if any. But I'd be very careful with loadbalancing and scope
> distribution, 99.99% of what I saw sofar sucked badly.
>
> regards
> Leon
>
>
>
>
>
>
>
> On 1/4/07, Daniel Chacón Sánchez <danielccss@(protected):
> > Thanks Leon!!!
> >
> > Ok I made it using the servletcontext like you have said :-), with this
> >
> > servlet.getServletContext().setAttribute("objHospital", objHospital);
> >
> > All works fine, even if the user made a mistake :)
> >
> > One question:
> >
> > 1- I dont understand something about the servletContext, which is the
> > problem of have multiple-server configuration? In both servers the data
> is
> > store in the servlet context right? I guess the problem is that in some
> > moment the objHospital in one server is diferent to the objHospital in
> other
> > server because it change in the database? Or that the actions of one war
> > don´t have the same servlet context that the actions on other war? I
> really
> > don´t understand this, can you explain me that, like i said all works
> fine
> > but i want to understand this.
> >
> > Thanks
> >
> >
>
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