André Warnier wrote: > - we have a JVM. That is the real process that is running, at the OS > level. That process can be killed, or decide to stop running, at which > point we don't have a JVM process anymore, and thus no Tomcat and no > webapps at all. That's kind of drastic and definitive. Yes.
> - "inside" the JVM, we have a Tomcat. Basically, that is only code > which the JVM is "running" (a bit like a Perl interpreter process runs > the list of Perl opcodes it has compiled a perl script into). Tomcat > can somehow decide that it is tired of living, and tell the JVM to stop > running it. At which point we have no webapps and no Tomcat anymore, > and consequently (I presume, but this is already a bit less clear), no > JVM anymore either, because not having anything to do anymore, it would > also exit. Or ? When Tomcat stops, it stops the JVM. > - then inside Tomcat, we have webapps. It's already getting more > mysterious there for me, but I resolve this intellectually by imagining > that a webapp is just a "subroutine" which Tomcat runs from time to > time, in response to a HTTP request for example. So a webapp in fact > "is" Tomcat, in the sense that when it runs it does so as an integral > part of the Tomcat process. So much so that if a webapp were to execute > a "system.exit()", it would take the whole Tomcat (and JVM) with it. Yes ? Correct. Unless you use a security manager which would stop the webapp calling system.exit() > So now, when the Tomcat Manager application decides to "stop a web > application", what it really does is just to prevent any further calls > to this web application in the future, by removing some entry in a table > of "runnable webapps". In other words, it does not really "stop" or > "kill" any currently running instance of that webapp (those are allowed > to finish what they are doing and "return()" to Tomcat main code), but > it makes it so that any further call to "/mywebapp" will be met by a > "what ?" response. It depends :). Normally a 404 (not found) will be sent. > Is this a correct interpretation ? Almost. New requests are rejected. Tomcat gives current requests a 'reasonable' period to stop processing. I forget what this is but it is of the order of tens of seconds. > Now comes the basic question : can a webapp stop itself, without taking > the whole Tomcat and JVM with it ? In other words, in response to > something (a variable being a certain value, or the interception of some > event or whatever), can my webapp decide to stop doing what it is > currently doing, clean up after itself, and then do something to prevent > itself ever being called again in the future of this Tomcat instance ? > (or say at least until some external intervention activates it again). Yes. It should be able to ask the manager to stop it or undeploy it. Mark --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
