Re: Re: [ANN] XINS 1.3 supports XML-RPC

Paul,


> >> - how much do you support keep-alive connections ? We have been using XML-RPC > Right... but when you use web-services from a far-away client browser,
> it's considerably higher... add to it a few proxies underway...

I know that with dial-up connections, it could really make a noticable
difference. Nowadays, I don' know. Have you done any performance
testing on this?

> Is it harder on the client or on the server ?

On the client. XINS uses Jakarta Commons HttpClient, which supports
Keep-alive. But the problem is that the architecture used by
HttpClient stands in the way of our approach. We have runtime
configuration files which specify the locations of the services. For a
"store" service with 3 different back-ends, the configuration could
read as follows:

capis.store=group, ordered, near, far
capis.store.near=service, http://apiserver2.localdomain/store/, 2000
capis.store.far=group, random, far1, far2
capis.store.far1=service, http://apiserver1.localdomain/store/, 5000
capis.store.far2=service, http://apiserver3.localdomain/store/, 5000

And we could have another remote service, called 'order':

capis.order=service, http://apiserver1.localdomain/order/, 3000

Now as you can, depending on the service, apiserver1 has a time-out
set of either 5 seconds or 3 seconds. But HttpClient is
server-oriented, so you typically set the time-out per server, which
is in our case a problem. If I remember correctly, that was the state
of the investigation.

> On the server we shall be using Tomcat anyways which does make his own
> management of keep-alive, I believe (am I wrong?). It should, thus,
> "just" be done for the client where, I though, Http-Client should be
> somewhat friendly.

Indeed, Tomcat has no problem keeping connections alive. Neither does
Apache. Do know that the combination of Apache and Tomcat using
mod_webapp can cause severe problems. At least with older versions of
mod_webapp. We saw latencies of about 200 milliseconds, which is
completely unacceptable in most situations.

I'll discuss internally whether we should still consider including
keep-alive as a potential feature for XINS 1.4.0.


Kind regards,


Ernst


 
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