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From Henri Gomez <>
Subject Re: Status/Authority of AJP/1.5
Date Sat, 29 Oct 2005 20:54:59 GMT
using AJP or HTTP or WHATEVERP protocol you want, the current need for
me in my production systems is to be able to add / remove a tomcat
machine to a LoadBalancing farm without having to restart the Apache 2
web server.

A  WEB admin (I work with them each days) would like to add / remove a
tomcat dynamically, for example using an admin webapp on an
'load-balancing administrator console'  running on a webapp hosted by
a tomcat or may be even a pure Apache 2 application.

If you told me it's impossible to add a REQUEST mapper (ie JkMount)
dynamically to a running Apache 2.0, I say amen and we'll wait for
HTTPD team to allow that.

But something we could do allready is to add/remove a tomcat from a lb worker ?

2005/10/25, Costin Manolache <>:
> On 10/25/05, Mladen Turk <> wrote:
> > Costin Manolache wrote:
> > > DBUS is a good example in IMO - I'm not
> > > saying to use their impl, which doesn't fit, just the protocol spec.
> >
> > The major power of AJP protocol is known-header-name indexing, and
> > IMHO there is no other protocol that is HTTP application focused.
> Well, any protocol can do this - with the right message.
> In this case: it'll be:
>  enum  knownHeadersCode={ .... }
>  and the message will have an array of ( knownHeaderCode, string ) and
> then ( string string)
> Or some other variation - there is nothing so special in Ajp that
> can't be encoded in a standard protocol. Except the fact that ajp is
> not extensible - so it may save a few bytes.
> > If there is really a need for a completely new protocol,
> > and I doubt there is a real need for that right now, we must presume
> > that the primary intent of the protocol is to allow communication of
> > two well known and defined http applications.
> Sure - but this can be expressed as well on top of a more standard (
> or common ) marshalling. Marshalling is not specific to any
> application, not even in ajp ( maybe the stupid 'first chunk' - but
> even this can be expressed with few extra bytes in a normal protocol
> ).
> The API you expose - i.e. the message signatures - should remain
> specific to the http
> app. And a standard protocol would allow you to add all kind of extra
> signatures.
> > If you look at the XDR protocol, each 'string' type message is prefixed
> > with additional two bytes compared with AJP, so beside that, the lack of
> > header indexing would at least double the packet size, and downgrade the
> > performance by twice.
> I don't think the 2 extra bytes is such a big problem.
> Actually there is one thing that is unique to AJP - the callbacks done
> over the same connection, as responses ( since tomcat can't initiate a
> call ). But even this can be expressed in a proper RPC - by having the
> callback as a normal response.
> Costin
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