load balancing tomcat

[David Mossakowski <dm...@Instinet.Com>]

Load balancing is performed at the connector level where the HTTP 
service chooses which instance of Tomcat to use, using the Tomcat engine 
identifier jvmRoute.

Both, mod_jserv and mod_jk connectors are able to be set up for load 
balancing.  I'm less certain of what to make of WARP and mod_webapp. 
This combination supposedly does not support load balancing but if 
someone knows any different please let me know.  I'm not sure about the 
HTTPConnector (Coyote?) that is used to setup HTTP server on default 
port 8080.  Could this connector be used for load balancing?  Has anyone 
done this?

Craig, I did not find any document concerning load balancing in docs in 
4.0.3 Tomcat installation.

For anyone interested in configuring load balancing:
- with mod_jk connector:
http://www.ubeans.com/tomcat/
http://bob.marlboro.edu/~msie/2002/it2/s5.html

- with jserv connector:
http://java.apache.org/jserv/howto.load-balancing.html
http://www.samag.com/documents/s=1155/sam0101a/0101a.htm

If anyone has any more articles on this please let me know.

Thanks,
d.


Craig R. McClanahan wrote:
> My opinions below ... others will undoubtedly disagree with some or all of
> them. :-)
> 
> On Wed, 26 Jun 2002, David Mossakowski wrote:
> 
> 
>>Date: Wed, 26 Jun 2002 16:09:29 -0700
>>From: David Mossakowski <dm...@Instinet.Com>
>>Reply-To: Tomcat Users List <to...@jakarta.apache.org>
>>To: Tomcat Users List <to...@jakarta.apache.org>
>>Subject: standalone tomcat or with apache
>>
>>Can someone please answer the following questions:
>>
>>1.  Is Tomcat used as a standalone server in a production environment or
>>always with Apache?
>>
> 
> 
> Sure.  You won't see Tomcat standalone running EBay or Yahoo, but you will
> see it running thousands of intranet based (and many small-to-medium sized
> Internet based) apps.
> 
> You should use Apache+Tomcat (or IIS+Tomcat or whatever) when you need it
> for performance/features/whatever.  If you don't need it, you'll save
> yourself a lot of configuration agony by running standalone.
> 
> 
>>2.  For a server that serves web applications only and no static html
>>files does it make sense to use Apache at all?  Would it be better to
>>use a standalone Tomcat?  Does Apache provide such better HTTP support?
>>
> 
> 
> Like almost every performance related question, the answer is "it
> depends".  In the "olden days" (i.e. last couple of years) the answer was
> often yes -- a combination of Apache's very optimized HTTP header parsing
> and relatively slow JDKs.  The gap for many apps has narrowed
> significantly.
> 
> The only way to know for *your* app is to try it both ways under realistic
> stress tests.  Fortunately, for most webapps, it is pretty transparent
> (from the app development point of view) to switch back and forth.
> 
> 
>>3.  If an application has 'images' directory in a web context directory
>>then will those images be served using Tomcat as well?
> 
> 
> Depends on which version of which web connector.  In most cases, the goal
> of the connector is to let Apache serve the static content.
> 
> 
>> If so then for
>>an application entirely made up of JSPs and servlets, all requests to
>>Apache would be forwarded to Tomcat, correct?
> 
> 
> All requests for JSPs and servlets will be forwarded, yes.  Whether that
> is 100% of the requests sent to your server is application dependent --
> lots of people like to take advantage of the fact that you can use a web
> server to serve static content at the same time.
> 
> Even if Tomcat serves static requests (either because the connector
> forwarded them, or because you are using Tomcat standalone), one thing to
> keep in mind is that browser caches can be your friend.  If you only have
> a few images for buttons or rounded corners, they will get served the
> first time and then get "Not Modified" responses for any future requests.
> 
> The performance delta on serving static files matters a lot more when
> caching is not helpful (i.e. no repeated requests for the same resources,
> or requests for so many resources that the cache is exhausted).
> 
> 
>>4.  Where can I find out more about distributing Tomcats across multiple
>>servers under a load balancer?  I only found
>>http://java.apache.org/jserv/howto.load-balancing.html from February
>>2000.  Does this document still hold for ajp13?
>>
> 
> 
> I think there's a corresponding document in the tomcat-docs webapp that
> comes with Tomcat 4, with current information.  But the concepts are
> pretty much the same (sessions are sticky, no dynamic migration from one
> Tomcat instance to another).
> 
> 
>>Thanks for any help,
>>d.
>>
>>--
>>David Mossakowski              dmoss@instinet.com
>>Instinet Corporation                 212.310.7275
>>
> 
> 
> Craig
> 
> 
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> 
> 
> 


-- 
David Mossakowski              dmoss@instinet.com
Instinet Corporation                 212.310.7275



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Tomcat 4.1.3 beta - Admin Interface

[Ben Ricker <br...@wellinx.com>]

Is there any documentation on the Admin interface? I ran into any number
of error messages...am I to assume that it more beta then everything
else?

Thanks,

Ben Ricker
Web Security System Administrator
Wellinx.com


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