It is not necessary to poll an Oracle database. Advanced queueing in combination with triggers provide an event driven framework.
Ed On Tue, Jan 6, 2009 at 5:28 PM, Mark Thomas <ma...@apache.org> wrote: > Bill Davidson wrote: > > Is it possible to set up a callback like situation so that a trigger in > an > > Oracle 10g database can call a method in a currently running webapp > > that's running in Tomcat 6? > > > > My situation is that I want to cache some infrequently changed database > > data in memory but when that data does change in the database, I want > > the web applications, running on multiple servers, to immediately pick > > up the change. > > > > Right now, one idea I have for this is to have the database trigger > > create a file in a file system that's shared by the database server and > > the application servers and have the web apps check for the existence > > of this file to know whether to update the cache. It feels ugly and > > means hitting a networked file system a lot but it seems like it should > > work and it seems like it should not be as bad as hitting the database > > constantly for something that doesn't change very often. > > > > I'd rather have the database send a message somehow to the web app that > > it needs to update its cache of the data. Any suggestions? > > 1. JMS? > 2. Call an reload servlet from the database? > 3. Drop the immediate update requirement and poll a data changed flag in > the db > every x seconds? > > Personally, I'd go with 3. For a simple flag this could be every few > seconds > with very little load on the db or Tomcat and would take all of a few > minutes to > code. > > Mark > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > >
