Thanks for your reply!
I am not an expert either. ;-) Here is my simple
thought after seeing your reply:
1. I know ajp protocol was originally introduced by
by mod_jserv to communicate with JServ. But what I
was wondering is, why at that time, a new protocol,
ajpxx was introduced rather using the existing http
protocol.
2. As I mentioned in my previous email, I have
already implemented http worker (very similar to ajp12
and ajp13 worker, with HTTP 1.0) in mod_jk. And it
works with Tomcat, Orion, JServ without any problem.
What it does is to simply forward the request to the
web container's http listener (like a proxy). (Thanks
for the great design of mod_jk!) When I compare the
performance between mod_jk/http/Tomcat and
mod_jk/ajp12/Tomcat, I can not see any difference.
3. I am working on implementing http 1.1 in my http
worker of mod_jk to take advantage of its persistant
connection with "KeepAlive" option. Once I am done, I
can compare the performance between
mod_jk/http1.1/Tomcat with mod_jk/ajp13/Tomcat because
ajp13 has persistant connection too.
4. There seems to have no difference between http and
ajpxx protocols on hooking up with other web servers,
such as IIS, Netscape, ...
5. Essentially, there is no difference between ajpxx
and http protocol in terms of forwarding the request
from the web server side to the web container side.
The only difference is the protocol itself.
6. So, my conclusion is, if there is no performance
difference, with the advantage of that http can cross
firewall and almost all web containers support have
http listeners, why http is not used in either
mod_jserv, mod_jk or mod_webapp? I must have missed
some points. :-)
Thanks.
-- Kevin
--- kevin seguin <[EMAIL PROTECTED]> wrote:
> i'm not the expert on these things, but i'll try to
> answer your
> questions as best i can. i'm sure if i say
> something that is blatantly
> wrong, i will be corrected ;) the information here
> is pretty much what
> i've figured out for myself using tomcat over the
> last year or so...
>
> >
> > I am using mod_jk right now and I am wondering why
> > ajp12, ajp13, and mod_webapp protocols were
> originally
> > introduced.
> >
>
> i believe the original reason why mod_jserv and ajp
> were introduced was
> for connecting the apache web server to the old
> JServ servlet
> container. when tomcat showed up, mod_jserv was
> used for it too. i
> think mod_jk, which added support for more web
> servers (i.e.
> iis/netscape) was then introduced as a replacement
> for mod_jserv. ajp13
> is an evolution (revolution??) of ajp12. it's
> faster.
>
> > http protocol can be passed through most firewalls
> > whereas ajp12 and ajp13 can not. In some real
> world
> > websites, there are lots of cases that there is an
> > inner firewall between Web server and web
> container.
> >
> > http protocol version 1.1's "keepalive" could be
> used
> > for consistant connections.
> >
> > Almost all the available web containers have at
> least
> > one http listener while some of them do not
> support
> > ajpxx protocols, such as the current Orion.
> >
>
> i'm not sure what this has to do with mod_jk/ajp...
>
> > I implemented an http worker in mod_jk by myself
> and
> > it works fine for me.
> >
> > So, my question is, what are the advantages of
> ajp12,
> > ajp13, and mod_webapp protocols versus http
> protocol?
> >
>
> i think you may have missed the point of ajp.
> mod_jk and ajp are used
> to connect web servers to tomcat. essentially what
> they do is intercept
> http requests in a web server and forward them to
> tomcat to be handled
> there. i'm not even sure if http could have been
> used to do this... it
> would have been weird, i think, because you have to
> forward all
> information about the request (headers, posted data,
> etc.) and if you
> made another http request from the web server to
> tomcat, you'd have a
> whole new set of headers and you'd have to have
> something to decode that
> request on the tomcat side and ... well, i'm
> rambling. i think ajp is
> just a cleaner and more efficient approach. also, i
> don't even know if
> the original JServ handled http...
>
> anyway, as i said, i'm not the expert on this
> subject, so hopefully
> someone with a better history with
> mod_jserv/mod_jk/ajp will correct any
> lies i may have told :)
>
> also, you should take a look at the documentation,
> particularly the
> mod_jk-howto and the ajp13 docs that come with
> tomcat 3.x (maybe only
> 3.3...).
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