Hi Brian and all jbosscache team,
Yes this is what I meant having the same benefit as if my class was
annotated with @Replicable, maybe on SET_AND_GET too.
By the way I cannot find any way to subscribe to the jbosscache-dev list
either through
http://post-office.corp.redhat.com/mailman/listinfo/ or
http://www.redhat.com/mailman/listinfo ?
Thanks
Jean
Brian Stansberry wrote:
> Copying to jbosscache-dev list. Jean, since you're doing caching work,
> suggest you subscribe to that list if you haven't already.
>
> I think your suggestion is definitely worth considering. If I
> understand you correctly, you're basically proposing something like
> adding a replication-trigger config to JBC, whereby with
> SET_AND_NON_PRIMITIVE_GET, JBC would track the type of any read and if
> not primitive, generate a cluster-wide write at transaction commit.
>
> Jean Deruelle wrote:
>> Hi Brian,
>>
>> Thinking a bit more about this.
>> You seems to have achieved in http sessions what is not possible to
>> do with Jboss cache natively and that is to me a drawback for Jboss
>> Cache ease of use.
>>
>> It is monitor automatically any changes to an object even if its
>> bytecode has not been enhanced by JBoss AOP...
>> Do you think it would not be better to integrate your code into Jboss
>> Cache this could help us to have a cleaner code and benefit others ?
>> Maybe with a note saying that it's less performing than if you
>> preprocess your classes with Jboss AOP (if my guess that it is less
>> performing is right...)
>>
>> wdyt ?
>> Best regards
>> Jean
>>
>> Brian Stansberry wrote:
>>> Jean Deruelle wrote:
>>>> Brian Stansberry wrote:
>>>> <snip/>
>>>>>
>>>>>>>> As a first version, I intend to try to keep things as
simple as
>>>>>>>> possible so my plan is "just" to store the
complete SipSession
>>>>>>>> object I have into the cache and let TreeCacheAop do the
job
>>>>>>>> when attributes are added/modified/removed to replicate
to
>>>>>>>> other node(s).
>>>>>>>>
>>>>>>>> I was looking at the AttributeBasedClusteredSession
>>>>>>>> implementation and one thing I fail to understand is why
it is
>>>>>>>> using a lot of transient map to handle session attributes
(all
>>>>>>>> attibutes, only modified, only removed Maps) instead of
letting
>>>>>>>> the Cache handling that for you ? Even for replication it
seems
>>>>>>>> to be done by hand through the storeSession method of the
>>>>>>>> JbossCacheManager class and the SnapshotManager class ?
>>>>>>>>
>>>>>>>
>>>>>>> This mostly relates to not forcing the user to have to
remember
>>>>>>> to call setAttribute if they modify an attribute:
>>>>>>>
>>>>>>> Set set = session.getAttribute("set");
>>>>>>> set.add(someObject);
>>>>>>> // oops, forgot to call setAttribute, updated set doesn't
>>>>>>> replicate!
>>>>>>>
>>>>>> I thought and still think this is not needed with TreeCacheAop in
>>>>>> doing putObject instead of put (see
>>>>>>
http://www.jboss.org/file-access/default/members/jbosscache/freezone/docs...)
>>>>>>
>>>>>> and it seems that it is already used for the
>>>>>> FieldBasedClusteredSession but that there is an overhead there of
>>>>>> creating observer for the pojo although the TreeCacheAop does the
>>>>>> exact same thing for you (at least that is my understanding of
>>>>>> TreeCacheAop as defined in the link above "Note that a user
will
>>>>>> only need to issue this call once for each POJO (think of it as
>>>>>> attaching POJO to cache management). Once it is executed,
>>>>>> TreeCacheAop will assign an interceptor for the pojo instance and
>>>>>> its sub-objects." but I start to think that my assumption is
>>>>>> wrong here... can you confirm ?)
>>>>>>
>>>>>
>>>>> To use putObject you have to use FieldBasedClusteredSession, and
>>>>> PojoCache (fka TreeCacheAop) can only add the interceptor, detect
>>>>> changes to the object etc. if the attribute's class has been
>>>>> bytecode enhanced by JBoss AOP. Not a default solution, since
>>>>> most users will not take the steps needed to bytecode enhance
>>>>> their classes.
>>>>>
>>>>> If you use putObject and the object is not bytecode enhanced,
>>>>> PojoCache has no idea if you subsequently change the object. So
>>>>> you're back to the issue of needing to deal with user forgetting
>>>>> to call setAttribute.
>>>> Ok it's clearer now and it all makes sense :-)
>>>> I guess even with JbossCache 2.x and Jboss 5.x we will need to deal
>>>> with the same thing then, right ?
>>>>
>>>
>>> Yes.
>>>
>>>> I was wondering if one could leverage the jboss-web.xml with new
>>>> tags in it to state which are the classes he wants to be
>>>> replicated. (with potentially pattern macthing)
>>>> On those classes, at load time, JbossAS would add automatically the
>>>> necessary Jboss cache annotation
>>>> (@org.jboss.cache.pojo.annotation.Replicable) through the javassist
>>>> library and the classes will be aspectized with load time weaving
>>>> and thus the full features of PojoCache could be used with no extra
>>>> code.
>>>> But I guess the problem here is that it still add some burden on
>>>> the end developer to describe things in jboss-web.xml and that
>>>> could be error prone so not an ideal solution neither I guess
>>>>
>>>
>>> If a user doesn't want to annotate their classes, they can deploy a
>>> jboss-aop.xml file to get the load time weaving. Adding the facility
>>> you describe in jboss-web.xml might make the syntax a bit easier,
>>> but it's doable now.
>>>
>>>
>>
>>
>
--
Brian Stansberry
Lead, AS Clustering
JBoss, a division of Red Hat
brian.stansberry(a)redhat.com