The number of clusters is not fixed but could shrink/expand at runtime
according to environment requirements. But even in a worst case scenario
I think that a number of 20 clusters is good enough so this is not a
concern for me anymore. Thanks for your explanations.
Emanuele
Shreedhar Ganapathy wrote:
>
>
> Emanuele wrote:
>> Application is not supposed to be message-intensive: nodes perform
>> local computation and than send aggregate date to some other node in
>> the cluster.
>> Anyway another concern to investigate regards the traffic weight
>> generated by multiple clusters in a subnet (heartbeat message, leader
>> election etc. etc.)
> How many clusters are we talking about here? In our QE testing
> environment at any given time we have at least 10 - 20 clusters
> testing the GlassFish or Sailfin appserver which contains Shoal as
> clustering engine. We have not seen any major issues with this.
> The heartbeat message is sent once every period (configurable -
> defaulted to 2 seconds) by each member using UDP.
> Leader election is a discovery process at startup after which it is
> deterministic so there is no network intensive leader election
> protocol during the lifetime of the cluster except at startup.
>>
>> Emanuele
>>
>> Shreedhar Ganapathy ha scritto:
>>>
>>>
>>> Emanuele wrote:
>>>> Certainly. This could be a solution. But the challenge is to have a
>>>> total decentralized system and a lus or a registry introduce a
>>>> certain degree of centralization.
>>>> I'm having a look at Shoal's code and JXTA api to understand how
>>>> world group can be used for the purpose.
>>>> Multicast port used by Shoal is fixed or changes from group to group?
>>> The address and port should ideally be different from group to group
>>> so that traffic in one group is not contaminating other groups. This
>>> is essential for group view changes for each lifecycle event such as
>>> a failure or a member join within a group and also for app level
>>> messages.
>>>
>>> BTW, what are your needs with respect to messaging throughput.
>>>>
>>>> Emanuele
>>>>
>>>> Shreedhar Ganapathy wrote:
>>>>> One could think of a registry or a lookup service a la Jini or a
>>>>> UDDI registry or a JMX based MBean that exposes an API for
>>>>> retrieving a collection of such Shoal groups. At the simplest
>>>>> level these could just be a list of group names. But the important
>>>>> part is the protocol for group discovery.
>>>>>
>>>>> Shreedhar Ganapathy wrote:
>>>>>> Yes, we can expose a GMS API that will allow for a Uber entity
>>>>>> for viewing a collection of groups. Jxta has traditionally had
>>>>>> the advantage of being able to expose a compositional pattern of
>>>>>> peergroups whereby a WorldPeerGroup composes of one or more
>>>>>> infrastructure netpeergroups.
>>>>>> I am hoping this can be done through Jxta. I am not sure if Mo is
>>>>>> suggesting that GMS have a separate process of discovering all
>>>>>> groups in a subnet. That would be a lot of design and development
>>>>>> work in the GMS layer.
>>>>>>
>>>>>> Emanuele wrote:
>>>>>>> My application is addressed to highly dynamic and fully
>>>>>>> decentralized environments which impose a decentralized
>>>>>>> discovery mechanism. Moreover I think such a feature could be
>>>>>>> essential to enable self-organizing capabilities in these settings.
>>>>>>>
>>>>>>> Emanuele
>>>>>>>
>>>>>>> Mohamed Abdelaziz wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> I think the simplest way is to expose a GMS API which allows
>>>>>>>> for discovery of active clusters, which should be easy in the
>>>>>>>> case of local sub-nets. It's a little tricky when crossing the
>>>>>>>> sub-net boundries, which can be overcome by distributed queries
>>>>>>>> cross networks, thus enabling such in geographically
>>>>>>>> distributed clusters. Do you see a need for such feature in
>>>>>>>> your application?
>>>>>>>>
>>>>>>>> Mohamed
>>>>>>>>
>>>>>>>> On Feb 15, 2008, at 5:07 PM, Emanuele <mane81_at_email.it> wrote:
>>>>>>>>
>>>>>>>>> Yes, something like that.
>>>>>>>>> I'll try to be more precise with an example: suppose there is
>>>>>>>>> a set of cluster in the system and clusters can be added and
>>>>>>>>> removed at runtime. Entities belonging to one cluster can move
>>>>>>>>> to another cluster according to some policies or rules. To
>>>>>>>>> support this sort of dynamism a way to find current active
>>>>>>>>> cluster is necessary.
>>>>>>>>>
>>>>>>>>> I think that I have to go deeper into JXTA api, but I would
>>>>>>>>> appreciate any useful hints because I'm really new to Jxta :)
>>>>>>>>>
>>>>>>>>> Emanuele
>>>>>>>>>
>>>>>>>>> Shreedhar Ganapathy wrote:
>>>>>>>>>> Does Jxta expose any api to query the world peer group for a
>>>>>>>>>> specific infrastructure netpeergroup by name ?
>>>>>>>>>>
>>>>>>>>>> I think something of that kind is what Emanuele is asking for.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Mohamed Abdelaziz wrote:
>>>>>>>>>>> Provided the cluster mcast port is known, discovery in world
>>>>>>>>>>> group could be employed to discover cluster instances, a
>>>>>>>>>>> functionality which could be exposed in shoal.
>>>>>>>>>>>
>>>>>>>>>>> Mohamed
>>>>>>>>>>>
>>>>>>>>>>> On Feb 15, 2008, at 2:14 PM, Shreedhar Ganapathy
>>>>>>>>>>> <Shreedhar.Ganapathy_at_Sun.COM> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> I am sure Jxta has some way to determine that. We probably
>>>>>>>>>>>> dont know of it and hence Shoal Apis dont expose it. Would
>>>>>>>>>>>> wait for Mohamed's response on this.
>>>>>>>>>>>>
>>>>>>>>>>>> Emanuele wrote:
>>>>>>>>>>>>> Hi.
>>>>>>>>>>>>> If I don't know any group names, there is a way to find
>>>>>>>>>>>>> the clusters currently instantiated in my network?
>>>>>>>>>>>>> Thanks
>>>>>>>>>>>>>
>>>>>>>>>>>>> Emanuele
>>>>>>>>>>>>>
>>>>>>>>>>>>>
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