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From André Warnier>
Subject Re: AJP vs HTTP connectors?
Date Tue, 03 Feb 2009 19:34:40 GMT

Maybe slightly off-topic, but having a moment of blues and lack of 
inspiration/motivation about working on what I should really be working 
on, and just in the spirit of communicating a "user experience"...

We are using Apache and Tomcat to provide an application, both on-site 
and in ASP mode, in total on about 50 different hosts right now. Our 
Apache/Tomcat setup is quite simple, and in fact just about the only 
original reason for which we are using Tomcat, is that one part of our 
application, which we get from another supplier, requires it as part of 
the interface to a back-end database system.  What we do on that 
database system is demanding from a system point of view, but not really 
stressful from a Tomcat or Apache/Tomcat connector point of view.  By 
that I mean that we do not have thousands of concurrent requests to 
Tomcat, it's more like 10-100 at the most. Neither do we need 
load-balancing or anything sophisticated like that, and we usually run 
just one Apache and one Tomcat on a single host.  (Not always, just most 
of the time).  We run this about 80% under Linux, 10% other Unixes, 10% 
Because we started this several years ago, we use mod_jk 1.2.x as a 
connector, as it was then the only connector available, and the setup 
was the same under Windows and Unix/Linux.

All of this to say that in all these years, I guess a reasonable number 
of hundreds of thousands (or millions) of requests have been processed 
through mod_jk, and we have never had any significant problem with it.

I had a problem a couple of months ago, due to a valid but peculiar 
configuration of mine (I tend to use "SetHandler jakarta-servlet" in 
Apache, rather than the more usual JkMount); I submitted the problem on 
this list and it elicited an immediate response, and a fix by Rainer 
Jung within the next 24h (at the most).

Even more recently, I had a customer problem in which basically mod_jk 
was not involved at all, but where the mod_jk log proved a very valuable 
source for tracking down the problem, and this list also proved a 
valuable source of information and suggestions.

I have had a look at mod_proxy_ajp, but did not find the available 
documentation very enlightening, nor the potential gains evident, and 
since indeed it seems to use the same AJP connector on the Tomcat side, 
and since we are basically happy with mod_jk, and since I am a great 
believer in the wisdom of the "if it ain't broke, don't fix it" maxim, I 
did not really pursue it very deeply.
That is not to say that mod_proxy_ajp is not good, I just never tried it.

Of course all that is also not to say that mod_jk might not be the right 
tool in other circumstances.  But as far as we are concerned, I would 
state it like this : if a customer would come to us saying that they had 
a problem with our application, the mod_jk module would be among the 
very last pieces which I would suspect of being involved in the problem.

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