Well, theoretically Tomcat 5 allows clustering: http://jakarta.apache.org/tomcat/tomcat-5.0-doc/cluster-howto.Html
And a set of tomcats can be load-balanced using various techniques: http://jakarta.apache.org/tomcat/tomcat-5.0-doc/balancer-howto.html
So you don't need to implement all this explicitly - what you have done in your WebDAV client-based front-end, right? Do I still miss something? I'm not an expert in this area, sorry.
My client app doesn't have the load-balancing support, we were planning on using a hardware http load-balancer/accelerator. We're also using Tomcat 4.1.30 not Tomcat 5 right now so we can't use Tomcat clustering. Whether a hardware load-balancer is significantly better than software load-balancing is arguable but we have used load-balancers for all of our apps in the past.
Tomcat clustering alone is not enough to cluster Slide servers. Tomcat
clusters allow you to spread load between multiple Tomcat servers but the
apps themselves don't automatically become "clusterable" simply because the
servlet engine is. Slide needs to be cluster-enabled too, to handle things
like caching correctly between all of the members of the cluster. The Slide
cluster shares a single content filesystem so that files are kept consistent
between the members. I don't know whether you can take advantage of
clustered slide servers from the slide api if it isn't a remote client api.
James may be able to shed more light on whether the api will work with slide api clients and clustered servers within Tomcat.
Tomcat handles clustering of the Session. As far as I know Slide doesn't make any use of the Session so Tomcat's clustering is really irrelevant. It won't hurt anything but it doesn't help, either.
-James
Warwick
-----Original Message-----
From: Andrey Shulinsky [mailto:[EMAIL PROTECTED] Sent: Monday, September 13, 2004 6:33 PM
To: 'Slide Users Mailing List'
Subject: RE: Using the slide api directly vs. using the webdav client
Can't one use the same scalable/clustered config but make requests
directly
- I mean, without this WebDAV client proxy? Please correct me, if I'm
wrong or if I
have misunderstood you. Or do you suggest running two application
servers - one for
the slide only and another for the custom back-end which
calls slide
by
means of the
WebDAV client - so that both can be load-balanced/clustered/etc.?
Right. I'm referring to a configuration that we're planning
to use with multiple slide servers that are clustered for failover and load-balancing with a single (or multiple) slide WebDAV client-based applications front-ending the servers and a HTTP load-balancer (or tomcat load-balancing)
in between. In this case if a single slide server goes down, or the load is high, then requests can be farmed out to the rest of the slide cluster for maximum uptime and performance. The slide servers share the same content repository between them.
With a slide api app that's coresident with the slide server, in the same web container and making calls directly to slide, then I didn't think it was possible for this client app to failover to another slide server (in another app server?) in the event of failure. That is, unless the slide api has been written to use remote calls to find other slide servers on the same machine or another machine? Or does J2EE take care of it somehow??
Well, theoretically Tomcat 5 allows clustering: http://jakarta.apache.org/tomcat/tomcat-5.0-doc/cluster-howto.
html And a set of tomcats can be load-balanced using various techniques: http://jakarta.apache.org/tomcat/tomcat-5.0-doc/balancer-howto.html So you don't need to implement all this explicitly - what you have done in your WebDAV client-based front-end, right? Do I still miss something? I'm not an expert in this area, sorry.
I really don't know enough about the possible scenarios for
deploying the slide api and server so I'll ask some questions about your configuration :-)
I understand. Frankly, our current client doesn't need all this clustering/load-balancing stuff - they have just about 30 users total. However, our solution could be sold to a couple of other companies who are considerably bigger so I'm very much interested in your work as well. :-)
What happens if the app server hosting your slide api client
and slide server goes down? Do you have a failover app server to go to in this event?
Does each failover app server run its own instance of the slide api app and slide server? Do the slide servers share the same content repository?
Right now we just have a failover server which content is synchronized with the main one's content once per... well... I believe, once per day, but I'm not sure. :-) It is supposed to be used if the main server crushes.
Yours sincerely, Andrey.
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