[infinispan-dev] Introducing JGroups scopes

[Bela Ban]

Let's take a step back and ask ourselves what it is that we want to 
scope ? Off of the top of my head the following things come to mind:

- HTTP sessions. I guess they're independent, so we can have a scope per 
session. Do you guys currently use 1 Cache per session ? Then Galder's 
suggestion below makes sense

- SFSBs: do we have 1 scope per bean ? What if bean X has a ref to bean 
Y ? Would they have to have the same scope ?

- Hibernate 2LC: scope per entity ? I don't know how entities are broken 
into tuples in the 2LC.



On 1/31/11 2:19 PM, Galder Zamarreño wrote:
> Hmmmm, not sure about adding a method to IC, cos that would lead to code like this which is very verbose:
>
> cache.getAdvancedCache().getInvocationContextContainer().getInvocationContext().setScope("X")
>
> As a user, I'd prefer something like:
>
> cache.getAdvancedCache().withScope("X")
>
> However, this would only be used to attach a particular scope. I envision a global, cache manager level configuration such as that marks all caches in that cache manager to be scoped by the cache name. That way, HTTP session repl code would need no changing at all and with a single flag, they could make each individual cache to act in its own scope. The code above would allow two caches to share the same scope for those situations where we want sequential calls for the two caches, i.e.:
>
> cache1.getAdvancedCache().withScope("X")
> cache1.put()
> cache2.getAdvancedCache().withScope("X")
> cache2.put()
>
> By the way, I don't understand your comment of "refine this scope by adding GlobalTransaction and so on".  If we take the cache1/cache2 example and imagine that these two would be called within a transaction, I'd imagine that the transaction itself would act as a scope and so would not need for a particular scope definition? i.e.
>
> tx.begin()
> cache1.put()
> cache2.put()
> tx.commit()
>
> At first glance, 5.0 would be the perfect target for this, but we'd need to take in account for any requirements coming from Paul since HTTP session repl could greatly benefit from it.
>
> As far as 2LC is concerned, within a deployment multiple txs will be operating on same caches so scoping could not be used. However different deployments could benefit from deployment level scoping so that messages for different caches can be sent in parallel. In AS environment different deployments could share the same 2LC cache manager and so the configuration option above would not work, but I'd need a deployment level scope that I'd use with cache.withScope().
>
> Cheers,
>
> On Jan 28, 2011, at 8:54 PM, Vladimir Blagojevic wrote:
>
>> Forgot to mention that scopes require addition of SCOPE protocol to the
>> stack. So we can probably do this on 5.0 branch only.
>> On 11-01-28 4:52 PM, Vladimir Blagojevic wrote:
>>> Hey,
>>>
>>> JGroups scopes [1] have been implemented for a while now and we should
>>> think about using them in Infinispan. I looked around a bit to see how
>>> we can use scope and satisfy requirements Manik outlined [2]. I think a
>>> good idea would be to introduce scope method in InvocationContext? We
>>> can start by implementing scope to return hash of cache name where
>>> invocation originated and subsequently refine this scope by adding
>>> GlobalTransaction and so on. Users, if they really need to scope their
>>> calls could do so by attaching additional markers to InvocationContext

-- 
Bela Ban
Lead JGroups / Clustering Team
JBoss