One could envision a rather complex and somewhat funky solution to
this... I'm not so sure I'd recommend it, but in the interest of
creative thinking...
(1) Add a context parameter isAppRunning to the webapp, initially set to
"false".
(2) Create a filter that is mapped to handle all requests. It checks
the value of isAppRunning, and redirects to some page if the value is
"false".
(3) Create a ContextListener that fires off a daemon thread.
(4) The daemon thread makes a simple request to some predefined URL of
the other webapp. If it does not get the response it expects, it sleeps
for a second or two and then tries again.
(5) When the daemon thread gets the reply it expects, it sets
isAppRunning to "true" and dies.
Now, add this all to the "master" webapp, that is, the one that depends
on the other. All requests should be blocked and redirected to the page
of your choice until the webapp it depends on returns that OK reply. I
could envision this being done with a number of webapps, forming a
dependency chain not unlike "depends" in Ant.
Will it work? I think so, but I just made it up, so who knows :)
Frank
SOA Work wrote:
argh. annoying.
ok. thx anyway.
-----Ursprüngliche Nachricht-----
Von: "Tomcat Users List" <users@tomcat.apache.org>
Gesendet: 24.04.06 17:57:49
An: "Tomcat Users List" <users@tomcat.apache.org>
Betreff: Re: is there a possibility to define the startup order for webapps?
A couple of other ideas:
Use a small shared class (in shared/lib) to keep track of whether the
database is running. The first webapp notifies this class when it's
ready, and the second webapp checks if the database is ready before
using it.
Or, just accept that database errors will occur during startup. This
is not a bad solution. From a user's point of view, when the server is
down all requests will return some kind of error, until the server is
back up and running. The only thing you can hope to gain is a better
error message for a few seconds during startup.
--
Len
On 4/24/06, David Smith <[EMAIL PROTECTED]> wrote:
This question comes up every so often and the answer is always no. The
webapp load order cannot be relied upon. In your case, might I suggest
the database webapp be run on a separate instance of tomcat? Can the
connection be done via TCP/IP?
--David
SOA Work wrote:
Hi there,
I'm currenttly using tomcat 5.x for running my webapps. Now I have the
following problem:
I'm using an database system which runs as webapplication inside tomcat.
Another webapplication needs the database connection for startup.
Everytime I restart tomcat the server doesn't get up, because the second webapp
ist started before the database webapp.
Is there a way to define the startup order of the webapplications deployed on a
server?
With wich system does tomcat choose the apps while startup? Could it be a
possibility to rename the folder of the webapps?
thx
Dominik
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