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Date: Mon, 9 May 2011 08:41:53 -0500
Message-ID: <BANLkTindi_mrj6=7iZ0_vOQTZjicTqPD7g@mail.gmail.com>
Subject: Re: High Availability in Tomcat?
From: Brian Braun <brianbraun@gmail.com>
To: Tomcat Users List <users@tomcat.apache.org>
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Hi Leon,

My budget is scarse, so I definitely should go for a soft balancer. And
certainly I see now that a balancer is the way I need to go.
My app will be an IP address geolocator, so my clients wont be humans with
browsers, but systems with HTTP components. So is it not going to be
sessions/cookies, each request will be considered as a new visitor. That
said, my needs are easier because I dont need to think about sessions and
cookies and how to preserve them.

However, I have read another email with an altervative complementary idea:
Parallel deployment. That would solve my problem with downtimes with
redeployments!  It seems to be something new in Tomcat 7. That would help me
with the redeployment issue, while I still need a solution for availability
with a balancer and two Tomcat instances. (Tomcat clustering?)

Thanks!!!!

On Mon, May 9, 2011 at 5:03 AM, Leon Rosenberg <rosenberg.leon@gmail.com>wrote:

> Hello,
>
> well, you provided not that many infos, but the usual way of doing
> this is to put multiple standalone tomcat instances behind a soft- or
> hardware loadbalancer (whatever your budget allows) and to make the
> app stateless, with cookie stickiness and failover.
> However, this will probably not make the site 100% available (which
> btw no site in the world is, not even google),
> since you will have at least node failure detection times (usually 3
> retries with 10 seconds timeout) and so on.
> However, you can reach 99,9X pretty easy with this scenario.
>
> regards
> Leon
>
> On Mon, May 9, 2011 at 6:17 AM, Brian Braun <brianbraun@gmail.com> wrote:
> > Hi,
> >
> > I'm about to launch a service on the internet, using Tomcat 7. This
> service
> > should be available 24x7, it should never be unavailable (or virtually
> > never). However, I will definitely be improving and correcting my app
> > frequently, so I will have to republish the WAR file very often. Not even
> > considering the fact that my app has leaking problems (that's another
> story)
> > and therefore I will have to restart Tomcat itself, republishing the app
> > will make it unavailable for at least 10 seconds while I do it.
> > I'm thinking that I need to create a Tomcat Cluster. Is that the way to
> go?
> > Any opinions?
> >
> > Another idea would be to have two tomcat installations, and to change the
> IP
> > my domain points to, to the IP that goes to that other Tomcat instance.
> But
> > changing the IP takes some time and I would have to wait until I think
> that
> > the DNS servers have updates the new IP, that would be slow and
> unreliable.
> >
> > Thanks in advance,
> >
> > Brian
> >
>
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