Re: [users@httpd] KeepAlive settings for reverse proxy (was: Apache module that enables ActiveX)

[Mauri <la...@gmail.com>]

Jonas, many thanks for your efforts to help me. Honestly I did not
understand what's the problem.
The anomaly I noticed is that:
Scenario A: client --> webserver application
The ActiveX (TeeChart) works. Sessions between client and WAS 2 are always
fixed (seeing the program TCPView on Windows)
Scenario B: client --> proxy --> webserver application
ActiveX (TeeChart) does not work. Sessions are many more as explained in
previous mail.

What I want is a test for setting the proxy between the client -> proxy ->
application only persistent sessions.
To do this I made these settings are correct?

ProxyPreserveHost On
MaxKeepAliveRequests 0
KeepAliveTimeout 60
KeepAlive On
ProxyRequests off
ProxyPass / http://10.173.90.171/
ProxyHTMLURLMap http://10.173.90.171 /
ProxyPassReverse http://10.173.90.171/ keepalive=On
ProxyHTMLEnable On
ProxyHTMLURLMap  /      /
RequestHeader    unset  Accept-Encoding



2010/4/23 Jonas Eckerman <jo...@frukt.org>

> On 2010-04-23 16:00, Mauri wrote:
>
>  many thanks jonas for your suggest. This is a part of my conf. Is it
>> correct?
>>
>
> I'm not clear on exactly what you want, so I'm guessing that you wan't
> keepalive *on* both from browser to proxy and from proxy to server. I'm also
> suspecting that you might have problems with connections between proxy and
> server dropping out.
>
> If this is not what you want, please correct my mistakes.
>
> And I still have no idea why you think this has anything to do with
> ActiveX.
>
>
>  [...]
>> KeepAlive On
>>
>
> That allows keepalive for the connections from browser to proxy. My guess
> is that this is what you want.
>
>
>          ProxyPassReverse http://10.173.90.171/
>>
>
> If you have problems with connections between proxy and server dropping
> out, you could try using changing this to:
>
> ProxyPassReverse http://10.173.90.171/ keepalive=On
>
>
>          SetEnv proxy-nokeepalive 1
>>
>
> That turns of keepalive *off* for conections from proxy to server. My
> *guess* is that this is not what you want.
>
> If you have problems with keeping connections alive between proxy and
> server and the keepalive parameter to the proxypass directive didn't help,
> this might help though.
>
>
> /Jonas
> --
> Jonas Eckerman
> Fruktträdet & Förbundet Sveriges Dövblinda
> http://www.fsdb.org/
> http://www.frukt.org/
> http://whatever.frukt.org/
>
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Re: [users@httpd] KeepAlive settings for reverse proxy

[Jonas Eckerman <jo...@frukt.org>]

On 2010-04-23 18:30, Mauri wrote:
> Jonas, many thanks for your efforts to help me. Honestly I did not
> understand what's the problem.

I think you need to read a tutorial or a book explaining how HTTP works. 
You seem to be confusing sessions with connections.


> The anomaly I noticed is that:
> Scenario A: client --> webserver application
> The ActiveX (TeeChart) works. Sessions between client and WAS 2 are
> always fixed (seeing the program TCPView on Windows)

Since HTTP is not a connection oriented protocol (even though it is 
normally used on top of TCP), sessions are independent from connections. 
Sessions in HTTP are usually handled by cookies, but can also be handled 
though query or post parameters.

I have absolutely no idea how your ActiveX thingy handles sessions.


> Scenario B: client --> proxy --> webserver application
> ActiveX (TeeChart) does not work. Sessions are many more as explained in
> previous mail.

Sessions and connections are two very different things. One session can 
be kept across multiple TCP connections, and it is possible (protocol 
wise) to have multple sessions during one TCP connection.


> What I want is a test for setting the proxy between the client -> proxy
> -> application only persistent sessions.

You do not need persistent connections to have persistent sessions.

If your application uses cookies for sessions, you should check what the 
cookies looks like. Especially you should check what (if any) host the 
cookies are issued for. A host mismatch may make the browser ignore them.


> To do this I made these settings are correct?

Not entirely. But it's hard to know since I don't know your setup or 
your application. How doid it work when you tried it out on your test setup?


 > ProxyPassReverse http://10.173.90.171/ keepalive=On

As written outside of a container, this makes no sense. The 
ProxyPassReverse directive needs to know what to change how.

Also, this is the wrong place to add the keepalive option. Sorry about 
that. See more below.

Inside a suitable location container and without the keepalive=on, the 
statement seems correct.

If your backend puts something else instead of http://10.173.90.171 in 
headers handled by ProxyPassReverse, you'd need to add a 
ProxyPassReverse for that. Please read the documentation at:
<http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypassreverse>

This does not take care of cookie based sessions though. If your 
application issues session cookies with hostnames/domains you need 
ProxyPassReverseCookieDomain as well. Please read:
<http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypassreversecookiedomain>


 > MaxKeepAliveRequests 0
 > KeepAliveTimeout 60
 > KeepAlive On

These settings configure wether or not to allow a browser to use 
persistent TCP connections to your proxy. This does not mean that the 
browser actually uses persistent connections, though most modern 
browsers are likely to do so.

It does not configure sessions.


 > ProxyPassReverse http://10.173.90.171/ keepalive=On

This is wrong, and I apoligize for that. It was my mistake. (Of course, 
if you had actually followed my advice and link and read the 
documentation, and had read the rest of my replies, that should have 
been clear.)

It should have been:
ProxyPass / http://10.173.90.171/ keepalive=On

Please note that this keepalive option means that the proxy tries keep 
persistent connections to the backend from dropping out by regularly 
sending a keepalive request. This only makes a difference if the backend 
allows persintent connections, the server tries to use them, but for 
some reason they are sometimes dropped.

Regards
/Jonas
-- 
Jonas Eckerman
Fruktträdet & Förbundet Sveriges Dövblinda
http://www.fsdb.org/
http://www.frukt.org/
http://whatever.frukt.org/

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