httpd-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Axel-St├ęphane SMORGRAV <Axel-Stephane.SMORG...@europe.adp.com>
Subject RE: [users@httpd] Reverse Proxy between WebSphere and the WebServer - prevent "Bad Gateway" errors.
Date Thu, 29 Jun 2006 08:02:52 GMT
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?

---------------------------------------------------------------------
The official User-To-User support forum of the Apache HTTP Server Project.
See <URL:http://httpd.apache.org/userslist.html> for more info.
To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
   "   from the digest: users-digest-unsubscribe@httpd.apache.org
For additional commands, e-mail: users-help@httpd.apache.org


Mime
View raw message