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List:       apache-httpd-users
Subject:    RE: [users@httpd] Reverse Proxy between WebSphere and the WebServer - prevent "Bad Gateway" errors.
From:       Richard de Vries <richard_devries () yahoo ! com>
Date:       2006-06-29 14:43:50
Message-ID: 20060629144350.75163.qmail () web36911 ! mail ! mud ! yahoo ! com
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Thanks for all your replies. I got in touch with IBM,
and WebSphere has a setting for this afterall. It's
called "Extended Handshake" and enabling it will allow
the plugin to do more extensive testing. I assume that
means it will check the HTTP return code in addition
to the port knock.

I tested it out, and it works flawlessly.

So, once again thank you very much for all your
assistance.


  R.

--- Axel-Stéphane  SMORGRAV
<Axel-Stephane.SMORGRAV@europe.adp.com> wrote:

> You are right. It does do port checks. Too bad it
> cannot determine that the application server is
> unavailable based on the HTTP 502 the reverse proxy
> would return in that case, and take the server off
> the list... Did you actually verify that?
> 
> Truly, we abandoned using WebSphere and WebLogic
> plugins long time ago and have since been using
> hardware load balancers that basically offer the
> same functionality as the plugins but are a lot more
> flexible in the way they can be configured. The load
> balancers do not do port checks (except in the case
> of SSL). Instead they pull a static page from the
> HTTP server (Apache, IIS, J2EE or whatever). If you
> insert an additional reverse proxy in between, it
> will still detect whether the application backend is
> available or not based on whether the status page is
> served. 
> 
> -ascs
> 
> 
> -----Original Message-----
> From: Richard de Vries
> [mailto:richard_devries@yahoo.com] 
> Sent: Wednesday, June 28, 2006 8:05 PM
> To: users@httpd.apache.org
> Subject: RE: [users@httpd] Reverse Proxy between
> WebSphere and the WebServer - prevent "Bad Gateway"
> errors.
> 
> True, it does routing and does simple port-checks I
> think to make sure the backend application server is
> up. If that backend server is down, it routes the
> request to an app server that is up.
> 
> In the proxy'd environment, this can happen:
> 
> a) the backend app server crashes / goes down
> b) the plugin, not knowing it's actually hitting a
> reverse proxy, does a port check and says "Hey, the
> WAS instance is up, let me send this request to
> you".
> c) the proxy tries to pass the request on to the
> app, gets no response, and returns a "bad gateway"
> error message which in turn is presented back to the
> client.
> 
> Without a proxy in the middle, this would happen:
> 
> a) the backend app server crashes / goes down
> b) the plugin tries to talk to the app server, sees
> its down, and reroutes the request to a different
> app server. The client gets the right data back and
> would be none-the-wiser.
> 
> So, how would I accomplish the latter with using the
> former?
> 
>
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