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From André Warnier>
Subject Re: Communicating between webapps
Date Wed, 08 Oct 2008 09:48:42 GMT
Leon Rosenberg wrote:
> RMI, CORBA or (worst choice) SOAP.
> Everything else, like using libs in shared/server folders etc are hacks :-)
> Leon
> On Wed, Oct 8, 2008 at 10:53 AM, Darryl Pentz <> wrote:
>> I have an issue where webapp A needs to let webapp B know about an event, and then
return a response to webapp B's processing of that event to the browser. So basically I need
to communicate between webapps in the same container.
>> I have not found a no-brainer solution to this as yet. The one I have tried is making
a localhost HTTP call which I find to be rather expensive, given that it requires creating
a socket connection to the same container.
>> I also just encountered the 'crosscontext' attribute in the <context.../> block
and was wondering whether that could serve any purpose.
>> Does anybody know of any tried and trusted ways of communicating between webapps
in Tomcat?
Maybe hacks, but why not use them if they are easier, faster, and have a 
smaller memory footprint ?
Not being very good at either Java or Tomcat, I'll submit the following 
ideas, and watch for comments :

Depending on what exactly you need to pass as information, why not just 
the fact of whether a given "flag" file exists in a directory under 
catalina.base ? I know that this sounds quite pedestrian, but 
considering that a webserver already makes zillions of file accesses 
anyway, I don't think the overhead of a few more would matter.

Or, if both webapps already use some common database, a record in ditto 
database. That is probably more flexible and more reliable re locking.

Or, a webapp with the appropriate permissions can set/reset/read a 
system property, and these should be shared by all apps under the same 
JVM instance, no ? what I don't know is if set/reset of a system 
property is "atomic".

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