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From Jules Gosnell <ju...@coredevelopers.net>
Subject Re: [wadi-dev] Re: [Geronimo] Clustering
Date Thu, 12 Jan 2006 10:18:51 GMT
Jules Gosnell wrote:

> Matt Hogstrom wrote:
>
>> Jules, I think you are spot on with a summary at this point.  At 
>> least in my conversations a person's view of clustering is influenced 
>> by which aspect of clustering they are intersted in.  I think a short 
>> doc would be really helpful here.  Were you planning on doing that or 
>> would you like some help?
>
>
> Matt,
>
> The more I look at the amount of work that needs doing the more help I 
> think I need !
>
> I am away this weekend, but I will try to put together a document 
> skeleton early next week that defines the areas that we need to cover. 
> Then we can refer back to various discussions on the list to flesh out 
> the relevant areas. I'm not sure of the best way of making this 
> document available so that everyone can contribute - but we can worry 
> about that when we have one.
>
> Do you have a pet clustering area ? Have we discussed it ?
>
> Jules
>
Guys,

I am on this - just have had a very busy week. I'll get back to the list 
with the goods ASAP.

Jules

>>
>> Jules Gosnell wrote:
>>
>>> Rajith Attapattu wrote:
>>>
>>>> Hmm,  again we have stopped the discussion :). Lets get it started 
>>>> again.
>>>
>>>
>>>
>>>
>>> OK - I will pick it up. I've been a bit preoccupied with WADI for a 
>>> while, so apologies for letting this one go cold.
>>>
>>>>  
>>>> So can we all come to some agreement (with more discussion) on 
>>>> which direction we might be taking !!
>>>>  
>>>> Like merging ActiveCluster and WADI or getting best of both worlds ?
>>>
>>>
>>>
>>>
>>> hmmm...
>>>
>>> not sure I follow you here...
>>>
>>> are you suggesting merging them because you view them as (a) 
>>> competing or (b) complimentary technologies ?
>>>
>>> If (a), then I need to put you straight. WADI is a technology that 
>>> builds on top of ActiveCluster (AC). AC provides basic clustering 
>>> fn-ality (most importantly, a membership abstraction along with 
>>> notifications of membership change).
>>>
>>> If (b), then, whilst WADI and AC could be merged, the current 
>>> separation is along clear and modular lines and I see no advantage 
>>> to collapsing the two projects into one.
>>>
>>> I think that there is far more reason to consider a merger between 
>>> ActiveSpace (AS). AS is a project that also builds upon 
>>> ActiveCluster to provide distributed caching fn-ality. The 
>>> fundamental difference (and I stand open to correction from James 
>>> here - I'm not very knowledgeable about AS) is that AS provides a 
>>> host of optimistic caching strategies, whilst WADI (currently) 
>>> provides a single, pessimistic strategy specifically designed for 
>>> the management of state in web and ejb tiers, where the sum of the 
>>> state in the tier is too great to be held by any single node. 
>>> Because WADI and AC fulfil similar roles, I think that there is more 
>>> to be gained by unifying their APIs and code-sharing between them. 
>>> James, if you are reading, what do you think ?
>>>
>>>>  
>>>> And also if we can define expectations/requirments for what we like 
>>>> for the next possible release (1.01 or whatever) in terms of 
>>>> clustering would give folks like me more direction as to where we 
>>>> should concentrate on?
>>>
>>>
>>>
>>>
>>> Well, I think that there has been plenty of discussion, but you are 
>>> correct in pointing out that there is no grand unified architecture 
>>> document out there. I did start on my suggestions towards one 
>>> quietly a while ago, but canned them. Perhaps enough discussion has 
>>> now occurred to put up a straw man ? Is this what you are looking for ?
>>>
>>>>  
>>>> If we decide on a direction maybe a few of us can start on a few 
>>>> prototypes and see what works best for Geronimo.
>>>
>>>
>>>
>>>
>>> Rajith, judging from our conversations on this list, your interest 
>>> seems to lie in JNDI clustering ? I think that we need to get you, 
>>> Gianny Damour (working on OpenEJB/WADI integration), James Strachan 
>>> (ActiveSpace) and Kresten Krab (Trifork guy involved in IIOP stuff, 
>>> which needs to be worked into equation) into a thread.
>>>
>>> OpenEJB will need cluster aware client-side proxies, delivered from 
>>> HA-JNDI. These proxies will need to talk to EJBs via OpenEJB's 
>>> proprietary protocol and Trifork's IIOP impl (I'm not on my home 
>>> ground here, so I might be off-base - but that is what the thread is 
>>> for). HA-JNDI needs a clustering substrate - ActiveSpace best fits 
>>> the bill (JNDI will be small amounts of data that are write-seldom 
>>> and read-often).
>>>
>>> One other issue that meshes with all of this is deployment. I've 
>>> given some thought to clustered deployment recently and come to the 
>>> conclusion that a deployment/app/?service? is simply a piece of 
>>> write(/[un]deploy)-seldom, read(/invoke)-often data. A deployment 
>>> may result in a number of entries being merged into HA-JNDI, an 
>>> undeployment may result in a number being removed. If a new node 
>>> joins a cluster (or subset of) that is responsible for providing an 
>>> HA-service/app, then that node should deploy an instance of that app 
>>> as it comes up and remove it as it goes down - i.e. a copy of that 
>>> app should be distributed to it and maintained by it for the 
>>> lifetime of the node, just as a jndi entry might be by a distributed 
>>> JNDI service.
>>>
>>> I haven't gone over these ideas with anyone else yet, particularly 
>>> with regards to the relevant JSR, but I guess they need to be thrown 
>>> out into the ring and discussed.
>>>
>>> Does everyone think that now is a good time to summarise the various 
>>> discussions that have occurred about clustering into some sort of 
>>> unified structure ? This can then be further discussed and hopefully 
>>> used to carve up work and produce a roadmap ? This is probably over 
>>> ambitious for a 1.0.1 release (it may just be a bug-fix release ?), 
>>> but something that we need to be getting on with.
>>>
>>>
>>> Jules
>>>
>>>>  
>>>> Regards,
>>>>  
>>>> Rajith Attapattu.
>>>>
>>>>  
>>>> On 1/5/06, *Rajith Attapattu* <rajith.attapattu@redknee.com 
>>>> <mailto:rajith.attapattu@redknee.com>> wrote:
>>>>
>>>>
>>>>
>>>>     -----Original Message-----
>>>>     From: Jules Gosnell [mailto: jules@coredevelopers.net
>>>>     <mailto:jules@coredevelopers.net>]
>>>>     Sent: Monday, December 19, 2005 9:55 AM
>>>>     To: dev@wadi.codehaus.org <mailto:dev@wadi.codehaus.org>
>>>>     Cc: wadi-dev@incubator.apache.org
>>>>     <mailto:wadi-dev@incubator.apache.org>; dev@geronimo.apache.org
>>>>     <mailto:dev@geronimo.apache.org>
>>>>     Subject: Re: [wadi-dev] Re: [Geronimo] Clustering
>>>>
>>>>     James Strachan wrote:
>>>>
>>>>     >
>>>>     > On 19 Dec 2005, at 14:14, Jules Gosnell wrote:
>>>>     >
>>>>     >> James Strachan wrote:
>>>>     >>
>>>>     >>> On 19 Dec 2005, at 11:53, Jules Gosnell wrote:
>>>>     >>>
>>>>     >>>> , whether there is other suitable Geronimo or ASF-licensed

>>>> code
>>>>     >>>> available, or whether we will need to write our own
WADI-
>>>>     >>>> autodiscovery classes. The important thing is to impose
as 
>>>> few
>>>>     >>>> dependencies on the client as possible. The client side
code
>>>>     >>>> should  literally be a few lines. Clients using clusters

>>>> should
>>>>     >>>> not  suddenly find themselves sucking down e.g. the
whole of
>>>>     >>>> activemq,  just to do a once off autodiscovery. Early
>>>>     versions of
>>>>     >>>> WADI had its  own autodiscovery code. If we need them,

>>>> they could
>>>>     >>>> be resuscitated.
>>>>     >>>
>>>>     >>>
>>>>     >>>
>>>>     >>> There's no reason why you can't do a simple implementation
of
>>>>     >>> ActiveCluster which doesn't use ActiveMQ - its just a 
>>>> simple API.
>>>>     >>
>>>>     >>
>>>>     >> Sure - but I'm talking about the EJB-client side - where we

>>>> just
>>>>     >> want to throw across as thin a line as possible, in order to
>>>>     haul a
>>>>     >> decent strength cable back. An EJB client would not need the
>>>>     >> ActiveCluster API (I'm not thinking in terms of making EJB 
>>>> clients
>>>>     >> fully fledged cluster members), but simply a way of locating

>>>> the
>>>>     >> cluster and requesting a membership snapshot of it.
>>>>     >
>>>>     >
>>>>     > Thats exactly what the ActiveCluster API is for :). Though by 
>>>> all
>>>>     > means come up with another API if you can think of a better 
>>>> way of
>>>>     > doing it.
>>>>     >
>>>>     >> This could be done by just broadcasting a query packet at a

>>>> well
>>>>     >> known multicast address and waiting for the first well-formed
>>>>     response.
>>>>     >
>>>>     >
>>>>     > Sure - an *implementation* of ActiveCluster API could do exactly
>>>>     that.
>>>>     >
>>>>     ???
>>>>
>>>>     well, maybe I'm thinking of the wrong piece of activecluster 
>>>> then ?
>>>>
>>>>     any piece of code could broadcast a packet... which piece of
>>>>     activecluster's API are you suggesting here ?
>>>>
>>>>     we really are talking about just a remoting proxy which needs to
>>>>     find,
>>>>     but not 'join' a cluster.
>>>>
>>>>     can you be more specific ?
>>>>
>>>>     Jules
>>>>
>>>>
>>>>     > James
>>>>     > -------
>>>>     > http://radio.weblogs.com/0112098/
>>>>
>>>>
>>>>
>>>>     --     "Open Source is a self-assembling organism. You dangle a 
>>>> piece of
>>>>     string into a super-saturated solution and a whole 
>>>> operating-system
>>>>     crystallises out around it."
>>>>
>>>>     /**********************************
>>>>     * Jules Gosnell
>>>>     * Partner
>>>>     * Core Developers Network (Europe)
>>>>     *
>>>>     *    www.coredevelopers.net <http://www.coredevelopers.net>
>>>>     *
>>>>     * Open Source Training & Support.
>>>>     **********************************/
>>>>
>>>>
>>>
>>>
>
>


-- 
"Open Source is a self-assembling organism. You dangle a piece of
string into a super-saturated solution and a whole operating-system
crystallises out around it."

/**********************************
 * Jules Gosnell
 * Partner
 * Core Developers Network (Europe)
 *
 *    www.coredevelopers.net
 *
 * Open Source Training & Support.
 **********************************/


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