Re: Using the slide api directly vs. using the webdav client

[James Mason <ma...@apache.org>]

Warwick Burrows wrote:
>>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:ashulinsky@arnoldworldwide.ca] 
>>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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