Hi Supun,

>From a Caching PoV, this is consistent. DB-loss can be momentary or
pro-longed, but that's not a concern of a cache. And, the prime use-case of
the cache is to make it possible to fetch cached resources instead of making
DB-calls. I see no inconsistency in this model, as Sumedha pointed out
earlier.

Proper exceptions are thrown when there is a loss of DB connectivity, if a
programmer needs to figure a loss of DB-connectivity (you can check the
cause - which is a Throwable; of the exception that's thrown by the
registry). But, to me, this is an edge-case, and if there is such a
consistency requirement the cache can be disabled. By default, caching is
enabled, and the changes have been made to the registry.xml files found in
carbon core, and files used for testing in carbon components and also at
product-level.

Thanks,
Senaka.

On Fri, Apr 22, 2011 at 5:11 PM, Supun Kamburugamuva <su...@wso2.com> wrote:

> Having Caching for fail cases transparently from the user gives an in
> consistency. Lets say a user accessed a resource before the registry
> database failed. After the registry database has failed, user can
> access this particular resource but he may not be able to access
> another resource. From a programmers perspective this is not
> consistent.
>
> Thanks,
> Supun..
>
> On Fri, Apr 22, 2011 at 4:58 PM, Afkham Azeez <az...@wso2.com> wrote:
> >
> >
> > On Fri, Apr 22, 2011 at 4:24 PM, Janaka Ranabahu <jan...@wso2.com>
> wrote:
> >>
> >>
> >> On Fri, Apr 22, 2011 at 3:47 PM, Waruna Ranasinghe <war...@wso2.com>
> >> wrote:
> >>>
> >>>
> >>> On Fri, Apr 22, 2011 at 3:39 PM, Supun Kamburugamuva <su...@wso2.com>
> >>> wrote:
> >>>>
> >>>> For the users of the registry, it is important to know weather
> >>>> registry database is down.
> >>>>
> >>>> For example we have the requirement of caching the resources at
> >>>> theimplemtation
> >>>> ESB level and manage these caches according to the ESB specific
> >>>> configurations. So I believe we have implemented something that should
> >>>> have being implemented at the application layer at the registry level.
> >>>>
> >>>> The correct way to implement this kind of functionalities in the
> >>>> registry is using an adapter kind of approach. If a user wants
> >>>> registry resource caching they can use a adapter to access the
> >>>> registry instead of direct access.
> >>>
> >>> Or we may introduce a mechanism to disable registry caching. In the
> >>> current implementation there is no way to disable registry caching.
> >>
> >> AFAIK Senaka did some changes recently and made registry caching
> >> configurable. Also with the default configuration registry caching is
> >> disabled.
> >
> > default should be caching enabled.
> >
> >>
> >> Thanks,
> >> Janaka
> >>>
> >>> Thanks,
> >>> Waruna
> >>>
> >>>>
> >>>> Thanks,
> >>>> Supun..
> >>>>
> >>>> On Fri, Apr 22, 2011 at 3:29 PM, Sumedha Rubasinghe <sume...@wso2.com
> >
> >>>> wrote:
> >>>> > How else would you expect a cache to behave? ;-)
> >>>> > /sumedha
> >>>> >
> >>>> > On Fri, Apr 22, 2011 at 3:27 PM, Supun Kamburugamuva <
> su...@wso2.com>
> >>>> > wrote:
> >>>> >>
> >>>> >> I tried to shut down the registry database and access the registry
> >>>> >> resources. It seems, even though the database is down registry is
> >>>> >> serving the resources from a cache. Is this the behavior of the
> >>>> >> registry?
> >>>> >>
> >>>> >> Thanks,
> >>>> >> --
> >>>> >> Supun Kamburugamuva
> >>>> >> Technical Lead &  Product Manager, WSO2 Inc.; http://wso2.com
> >>>> >> Member, Apache Software Foundation; http://www.apache.org
> >>>> >> WSO2 Inc.;  http://wso2.org
> >>>> >> E-mail: su...@wso2.com;  Mobile: +94 77 431 3585
> >>>> >> Blog: http://supunk.blogspot.com
> >>>> >> _______________________________________________
> >>>> >> Carbon-dev mailing list
> >>>> >> Carbon-dev@wso2.org
> >>>> >> http://mail.wso2.org/cgi-bin/mailman/listinfo/carbon-dev
> >>>> >
> >>>> >
> >>>> > _______________________________________________
> >>>> > Carbon-dev mailing list
> >>>> > Carbon-dev@wso2.org
> >>>> > http://mail.wso2.org/cgi-bin/mailman/listinfo/carbon-dev
> >>>> >
> >>>> >
> >>>>
> >>>>
> >>>>
> >>>> --
> >>>> Supun Kamburugamuva
> >>>> Technical Lead &  Product Manager, WSO2 Inc.; http://wso2.com
> >>>> Member, Apache Software Foundation; http://www.apache.org
> >>>> WSO2 Inc.;  http://wso2.org
> >>>> E-mail: su...@wso2.com;  Mobile: +94 77 431 3585
> >>>> Blog: http://supunk.blogspot.com
> >>>> _______________________________________________
> >>>> Carbon-dev mailing list
> >>>> Carbon-dev@wso2.org
> >>>> http://mail.wso2.org/cgi-bin/mailman/listinfo/carbon-dev
> >>>
> >>>
> >>>
> >>> --
> >>>
> -------------------------------------------------------------------------
> >>> Waruna Ranasinghe
> >>> Senior Software Engineer, WSO2
> >>>
> >>> Mobile: +94 724 318285
> >>> BLOG: http://warunapw.blogspot.com
> >>>
> >>> www.wso2.com - "Lean . Enterprise . Middleware"
> >>>
> >>> _______________________________________________
> >>> Carbon-dev mailing list
> >>> Carbon-dev@wso2.org
> >>> http://mail.wso2.org/cgi-bin/mailman/listinfo/carbon-dev
> >>>
> >>
> >>
> >>
> >> --
> >> Janaka Ranabahu
> >> Software Engineer
> >> WSO2 Inc.
> >> Mobile +94 718370861
> >> Email : jan...@wso2.com
> >> Blog : janakaranabahu.blogspot.com
> >>
> >> _______________________________________________
> >> Carbon-dev mailing list
> >> Carbon-dev@wso2.org
> >> http://mail.wso2.org/cgi-bin/mailman/listinfo/carbon-dev
> >>
> >
> >
> >
> > --
> > Afkham Azeez
> > Senior Software Architect & Senior Manager; WSO2, Inc.; http://wso2.com,
> >
> > Member; Apache Software Foundation; http://www.apache.org/
> > email: az...@wso2.com cell: +94 77 3320919
> > blog: http://blog.afkham.org
> > twitter: http://twitter.com/afkham_azeez
> > linked-in: http://lk.linkedin.com/in/afkhamazeez
> >
> > Lean . Enterprise . Middleware
> >
> > _______________________________________________
> > Carbon-dev mailing list
> > Carbon-dev@wso2.org
> > http://mail.wso2.org/cgi-bin/mailman/listinfo/carbon-dev
> >
> >
>
>
>
> --
> Supun Kamburugamuva
> Technical Lead &  Product Manager, WSO2 Inc.; http://wso2.com
> Member, Apache Software Foundation; http://www.apache.org
> WSO2 Inc.;  http://wso2.org
> E-mail: su...@wso2.com;  Mobile: +94 77 431 3585
> Blog: http://supunk.blogspot.com
> _______________________________________________
> Carbon-dev mailing list
> Carbon-dev@wso2.org
> http://mail.wso2.org/cgi-bin/mailman/listinfo/carbon-dev
>



-- 
*Senaka Fernando*
Product Manager - WSO2 Governance Registry;
Associate Technical Lead; WSO2, Inc.; http://wso2.com*
Member; Apache Software Foundation; http://apache.org

E-mail: senaka AT wso2.com
**P: +1 408 754 7388; ext: 51736*; *M: +94 77 322 1818
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*Lean . Enterprise . Middleware
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