If I run 2 web applications in a Tomcat, is that 2 web application run by 2
JVMs or 1 JVM?
Hello
1 JVM.I suppose it is virtual
Does that means that it is impossible to implement RMI between them, since
RMI requires at least 2 JVM to work?
1) you might have to write a patch and alter tomcat to add a hook into
the bootstrap to do this "under the table"..
a garden variety static class will let anyone communicate with anyone
in a JVM.
James said:Thanks.
Does that means that it is impossible to implement RMI between them, since
RMI requires at least 2 JVM to work?
Depends ... if the different web applications are loaded via differentanyone communicate with anyone within a JVM.
It probably does mean that you cannot do RMI between the two apps, but
I'm not certain of it. A better question for you to think about,
however, is whether it makes sense to split things up into two web
applications in the first place when they are tightly enough bound
together that you /want/ to do RMI between them.
Roedy Green said:More precisely the static variables of a garden variety class will let
anyone communicate with anyone within a JVM.
i believe, if you are under 1 jvm you would be able to share objects
between the two contexts.
things to try (in any order of preference)
1) you might have to write a patch and alter tomcat to add a hook into
the bootstrap to do this "under the table"..
2) the more appropriate way would be to do it "above the table", and
have a servlet to servlet communication through a post/get... assuming
the table is conceptually at the context level.
3) another possibility i just thought of, is to do this via jndi.
that's kinda the purpose of it. and probably the best solution.
4) run two seperate jvm's and then rmi would make more sense.
www.binaryfrost.com
I am not sure how a static class can help web app A calling and getting
results from web ap B. Can you give an example?
Roedy Green said:In a very simple example:
public class Common
{
public static string share;
}
A has code like this:
Common.share = "I will meet you at the casbah";
B has code like this:
if ( Common.share != null ) ...
In a real example A and B could call methods of Common and Common
would call methods in the concurrent package. See
http://mindprod.com/jgloss/queue.html
James said:Hi John,
The 2 web application serves different purposes but web app A requires some
information from web app B.
So for my case, it make sense to split them, and to communicate via RMI.
However I also forsee a possibility that they may be hosted in the same
container. Hence my questions in this threads.
I will probably code some functions to allow switching of RMI with an
alternative solution that is recomended in this thread.
John C. Bollinger said:I personally would prefer a solution that works all the time. I see two
alternatives that look reasonable:
1) App A obtains the needed information from app B through appropriate
methods on B's web interface. If you like buzz words, you could
describe this as B providing a web service that A uses. This approach
makes sense if providing the required information falls in, or close to,
B's general area of operation.
2) App A and app B share a common back end with which they both
communicate, but which is logically separate from either. They don't
communicate directly. The back end might be as simple as a common
database, or as complex as a full-blown J2EE application comprising one
or more EJBs, etc. A simpler RMI-based back end would fall in the
middle, and there are other alternatives as well.
I don't particularly care for the idea of B providing a back-door
interface for A to use to get a hold of information that B just happens
to be holding (though it's not clear whether that's what you were asking
about).
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