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From Chris Gamache <>
Subject Re: Parallel Deployment: Can I request a specific webapp version?
Date Tue, 21 Jul 2015 16:07:30 GMT
+1 here. This would be nice to have a standard way to manage different logical versions of
the same webapp to handle split-braining client and server code. That's my million dollar

So, the idea floated by this fine group of list participants was to deploy and use cookies
that a reverse proxy would decode to send your users to different back ends. That only gets
you halfway to where you're going. Say you have version 1.0 and 1.1. Any patches not requiring
reload could be deployed with #001,#002, but you would need to deploy two or more of the same
webapp to get different urls: /webapp-1.0 and /webapp-1.1. The whole idea of the parallel
deployment is to get the old version of the webapp undeployed asap. If you have different
logical versions that need to remain... Well, using the management servlet you can programmatically
undeploy your obsolete webapps at your leisure.   

I'm sure there's always a better idea lurking around out there though. 


> On Jul 19, 2015, at 3:49 PM, Hartmut Honisch <> wrote:
> Hi everyone,
> I'm using Tomcat's parallel deployment feature, and I wonder whether
> there's a way to request a specific version of my webapp.
> Let's say I have a WAR named myapp##001.war deployed on my server and just
> deployed a new WAR myapp##002.war.
> Requests to http:/myserver/myapp/.. are transparently mapped by Tomcat to
> version 001 for existing sessions and to version 002 for new sessions.
> Is there a way to explicitly request version 001, like
> http://myserver/myapp##001/...? That specific syntax obviously doesn't
> work, otherwise I wouldn't be asking :)
> BTW: The reason I'm asking is because that transparent shift from one app
> release to the next doesn't play along well with any caches (browser,
> caching proxies, CDNs etc.):
> When a shift to the next app release occurs, I generally need the client
> browsers to fetch a fresh copy of all files belonging to that release. And
> the only way to force them to do that is by having them use a different URL
> than for the old app release files..
> So my idea is to have the browser make an initial request to
> http://myserver/myapp/, when launching the app, which
> instantaneously redirects to the actual release-specifc URL
> http://myserver/myapp##00x/... , thereby having the browser use
> release-specific URLs for all application files.
> Any help is appreciated.
> Thanks
> - Hartmut

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