mod_jk - apache tomcat problem

[Chong Yu Meng]

Hi Lonni !

Net Llama! wrote:

> The missing tidbit that I should have probably mentioned is this isn't 
> so much my server, as just needed for the product that my employer 
> sells.  So i'm not all that atuned to the technologies behind it.
>
Ow ! That's going to be tough to support. Tomcat configuration can be a 
special kind of hell. I still have problems with certain combinations 
and scenarios, which was why I put my document together in the first 
place. The documentation on the Jakarta site is a little sparse, and if 
you're coming to Tomcat from a non-Java background, or if you're new to 
Tomcat as a servlet engine, it can be a little scary.

Anyway, if you need to do a deployment (or support one), here are a few 
things to watch out for:

1. The Java SDK you use is crucial -- for RHEL or any Linux distribution 
with NPTL enabled, use 1.4.1 or better. If you're using Sun's Java SDK, 
test that Tomcat runs properly *with the web application*, before doing 
further configuration or integration with Apache. Some of the early 
version releases have been buggy. You don't want to waste time 
troubleshooting Tomcat if it is a Java problem.

2. For mod_jk2, use the source tarball. Ignore the part in the README 
that says you should run the Ant task. It doesn't work. The instructions 
in my document will give you the make process and the necessary 
switches. Please ensure that all necessary packages are installed, 
because the make process doesn't tell you much about any errors and they 
are easy to miss.

3. For integration with Apache using mod_jk2, you will need to know how 
the servers are deployed:
- Tomcat + Apache on same server (UNIX/Linux) ==> UNIX sockets, channel 
sockets
- Tomcat + Apache on same server (Windows) ==> JNI, channel sockets
- Several Apache servers + 1 Tomcat server ==> channel sockets
- 1 Apache server + several Tomcat servers ==> channel sockets

There is actually an easier method of integrating Apache and Tomcat 
without using mod_jk or mod_jk2. You can setup Apache as a reverse proxy 
and connect Tomcat to it. The problem with that approach is that Tomcat 
only sees one client -- Apache, and there were some reports of session 
problems. I'm not too clear on the specifics there.

Anyway, I'm looking to expand the document, especially with regards to 
load balancing and channel sockets, so if you need to use those, just 
let me know. I'd like to help out.

Regards,
pascal chong