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Date: Sun, 16 Oct 2005 06:50:36 -0600
From: Jeff Genender <jgenender@savoirtech.com>
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To: dev@geronimo.apache.org
Subject: Re: Clustering
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Surendra,

We would be very interested in seeing what you have to offer ;-)

Please tell us more as I am intrigued about your product.  I guess the 
best way is to start, is telling us about what you would like to 
contribute and this will involve discussion from the community and team, 
and we can  proceed forward from there.  We have several steps we would 
need to go through (i.e. licensing, finding it a home in the source, 
etc), but community discussion is always first ;-)

Thanks for your desire to contribute,

Jeff

Surendra Reddy wrote:
> We, at Optena, are also working a proposal Geronimo Grid Architecture.
> How can we involve and contribute in this activity?
> 
> -Surendra
> 
> --
> Surendra Reddy
> Founder and Chief Technology Officer
> Optena Corporation
> 2860 Zanker Road,
> San Jose, CA 95135
> skreddy@optena.com
> 
> 
> -----Original Message-----
> From: Dave Colasurdo [mailto:davecola@earthlink.net] 
> Sent: Saturday, October 15, 2005 5:05 AM
> To: dev@geronimo.apache.org
> Subject: Re: Clustering
> 
> 
> 
> Jules Gosnell wrote:
> 
>>Jeff Genender wrote:
>>
>>
>>>Now that we have achieved the covetted J2EE Certification, we need to
> 
> 
>>>start thinking about some of the things we will need to have in 
>>>Geronimo in order to be mass adopted by the Enterprise.
>>>
>>>IMHO, I think one of the huge holes is clustering.  This is a heavy 
>>>need by many companies and I believe that until we get a powerful 
>>>clustering solution into G, it will not be taken as a serious J2EE 
>>>contender.
>>>
>>>So, with that said, I wanted to start a discussion thread on 
>>>clustering and what we need to do to get this into Geronimo.  I 
>>>personally would like to be involved in this (thus the reason for me 
>>>starting this thread) - yeah, since Tomcat is done, now I am bored
> 
> ;-).
> 
>>>I was going over the lists and emails and had some great discussion 
>>>with Jules on the WADI project he has built.  This seems compelling
> 
> to 
> 
>>>me.  I also noticed Active Cluster as a possibility.
>>>
>>>So lets start from the top.  Do we use an already available clusering
> 
> 
>>>engine or do we roll our own?  Here is a small list of choices I have
> 
> 
>>>reviewed and it is by no means complete...
>>>
>>>1) WADI
>>>2) Active Cluster
>>>3) Leverage the Tomcat Clustering engine
>>>
>>>So here are some of my questions...
>>>
>>>How complete is WADI and Active Cluster?  Both look interesting to
> 
> me. 
> 
>>>My only concern with Active Cluster is it seems to be JMS based,
> 
> which 
> 
>>>I think may be slow for high performance clustering (am I incorrect
> 
> on 
> 
>>>this?).  How mature is WADI?
>>
>>
>>Here is a status report on WADI.
>>
>>I'm developing it full time.
>>
>>A snapshot is available at wadi.codehaus.org - documentation is in the
> 
> 
>>wiki - at the moment the documentation (rather minimalist) is more up
> 
> to 
> 
>>date than the snapshot, but I will try to get a fresh one out next
> 
> week.
> 
>>WADI is a plugin HttpSession Manager replacement for Tomcat-5.0/5.5
> 
> and 
> 
>>Jetty-5.1/60 (it can actually migrate sessions between all four in the
> 
> 
>>same cluster).
>>It comprises a vertical stack of pluggable caches/stores (memory,
> 
> local 
> 
>>disc, db etc) through which sessions are demoted as they age and 
>>promoted as and when required to service a request.
> 
> 
> Can you please clarify the purpose of promotion/demotion of 
> httpsessions? Is this a mechanism to age old entries out of the cache? 
> How does this relate to httpsession inactivity timeouts?
> Is the cache size configurable?
> 
> 
>>This stack may be connected horizontally to a cluster by inserting a 
>>clustered store, which uses a distributed hash table (currently 
>>un-replicated, but I am working on it) to share state around the 
>>clusters members in a scalable manner. WADI has a working mod_jk 
>>integration.
> 
> 
> Does this mean that each cluster member shares it's httpsession data 
> with all of the other members (1-> all) or is there the notion of 
> limiting the httpsession replication to one (or a few) designated 
> partners?
> 
> 
> 
>>WADI currently sits on top of ActiveCluster, which it uses for 
>>membership notification and ActiveMQ which is used for transport by
> 
> both 
> 
>>layers. ActiveMQ has pluggable protocols, including a peer:// protocol
> 
> 
>>which allows peers to talk directly to one another (this should put to
> 
> 
>>bed fears of a JMS based solution not scaling - remember, JMS is just
> 
> an 
> 
>>API). So you do not need to choose between WADI and ActiveCluster -
> 
> they 
> 
>>are complimentary. ActiveCluster can also (I believe) use JGroups as a
> 
> 
>>transport - I haven't tried it.
>>
>>ActiveSpace is another technology in this area (distributed caching)
> 
> and 
> 
>>it looks as if WADI and ActiveSpace will become more closely aligned.
> 
> So 
> 
>>this may also be considered a complimentary technology.
>>
>>Both Tomcat and Jetty currently have existing clustering solutions. I 
>>looked closely at the Tomcat solutions before starting out on WADI and
> 
> 
>>knew all about the Jetty solution, because I wrote it :-). WADI is my 
>>answer to what I see as shortcomings in all of the existing open
> 
> source 
> 
>>approaches to this problem-space.
>>
> 
> Can you provide a quick high level description of the advantages of WADI
> 
> over Tomcat and Jetty clustering solutions?
> 
> 
> 
>>Some parts of WADI should soon (December) be undergoing some serious 
>>testing. When they pass we will be able to consider them production 
>>ready. Others, notably the distributed hash table are still under 
>>development (although a fairly functional version is available in the 
>>SNAPSHOT).
>>
>>I think that, in the same way Tomcat clustering could be enabled
> 
> easily 
> 
>>in Geronimo, WADI could also be added by virtue of its integration
> 
> with 
> 
>>Tomcat/Jetty, but I have been concentrating on my distributed hash
> 
> table 
> 
>>too hard. If anyone is interested in talking further about WADI,
> 
> perhaps 
> 
>>trying to plug it into Geronimo (It is spring-wired and uses spring to
> 
> 
>>register its components with JMX. I guess it should be simple to hook
> 
> it 
> 
>>into the Geronimo kernel in the same way, I just haven't had the
> 
> time), 
> 
>>or helping out in any way at all, I would be delighted to hear from
> 
> them.
> 
>>I have broached the subject of a common session clustering framework 
>>with members of the OpenEJB team and we have discussed things such as 
>>the colocation of HttpSessions and SFSBs. I believe OpenEJB has been 
>>moving towards JCache to facilitate the plugging in of a clustering 
>>substrate. My distributed hash table is also moving in the same
> 
> direction.
> 
> So, if I understand correctly, you are working towards some common 
> infrastructure with openejb.. though WADI itself, will not address 
> clustering beyond the Web Tier?
> 
> Thanks for the update!
> 
> 
>>I hope that gives you all a little more information to go on. If you 
>>have any questions, just fire away,
>>
>>
>>Jules
>>
>>
>>
>>>Thoughts and opinions are welcomed.
>>>
>>>Jeff
>>
>>
>>
>>