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From Nikolay Izhikov <nizhi...@apache.org>
Subject Re: Reference of local service.
Date Mon, 02 Mar 2020 13:08:42 GMT
Hello, Vladimir.

> What if we just provide an option to disable service metrics at all?

I don't think we should create an explicit property for service metrics.
We will implement the way to disable any metrics in the scope of
IGNITE-11927 [1].

> Usage of a proxy instead of service instances can lead to performance
> degradation for local instances, which is another argument against such
change.

As far as I know, many and many modern frameworks use a proxy approach.
Just to name one - Spring framework works with the proxy.

We should measure the impact on the performance that brings proxy+metric
and after it make the decision on local service metrics implementation.
Vladimir, can you, as a contributor of this task make this measurement?

[1] https://issues.apache.org/jira/browse/IGNITE-11927

пн, 2 мар. 2020 г. в 12:56, Vladimir Steshin <vladsz83@gmail.com>:

> Denis, Vyacheslav, hi.
>
> What if we just provide an option to disable service metrics at all? It
> would keep direct references for local services. Also, we can make service
> metrics disabled by default to keep current code working. A warning of
> local service issues will be set with the option.
>
> пн, 2 мар. 2020 г. в 11:26, Vyacheslav Daradur <daradurvs@gmail.com>:
>
> > >> Moreover, I don't see a way of implementing such a check. Are you
> going
> > to look just for any interface? What about Serializable? Will it do?
> >
> > The check should look for the interface which implements
> > "org.apache.ignite.services.Service", it covers the requirement to be
> > Serializable.
> >
> > >> For now though the best thing we can do is to calculate remote
> > invocations only, since all of them go through a proxy.
> >
> > Let's introduce a system property to manage local services monitoring:
> > - local services monitoring will be disabled by default - to avoid any
> > backward compatibility issues;
> > - local services monitoring can be enabled runtime with a known
> limitation
> > for new services for example;
> > Moreover, if we introduce such a feature flag to ServiceConfiguration -
> > the new feature can be enabled per service separately.
> >
> > What do you think?
> >
> >
> >
> > On Mon, Mar 2, 2020 at 12:33 AM Denis Mekhanikov <dmekhanikov@gmail.com>
> > wrote:
> >
> >> Vladimir, Slava,
> >>
> >> In general, I like the idea of abstracting the service deployment from
> >> its usage, but there are some backward-compatibility considerations that
> >> won't let us do so.
> >>
> >> Or we can declare usage of services without interfaces incorrect
> >>
> >>
> >> I don't think we can introduce a requirement for all services to have an
> >> interface, unfortunately. Such change can potentially break existing
> code,
> >> since such requirement doesn't exist currently.
> >> Moreover, I don't see a way of implementing such a check. Are you going
> >> to look just for any interface? What about Serializable? Will it do?
> >>
> >> Usage of a proxy instead of service instances can lead to performance
> >> degradation for local instances, which is another argument against such
> >> change.
> >>
> >> I think, it will make sense to make all service invocations work through
> >> a proxy in Ignite 3.
> >> For now though the best thing we can do is to calculate remote
> >> invocations only, since all of them go through a proxy.
> >> Another option is to provide a simple way for a user to account the
> >> service invocations themselves.
> >>
> >> What do you guys think?
> >>
> >> Denis
> >>
> >>
> >> вт, 25 февр. 2020 г. в 16:50, Vyacheslav Daradur <daradurvs@gmail.com>:
> >>
> >>> It is not a change of public API from my point of view.
> >>>
> >>> Also, there is a check to allow getting proxy only for an interface,
> not
> >>> implementation.
> >>>
> >>> Denis, what do you think?
> >>>
> >>>
> >>> вт, 25 февр. 2020 г. в 16:28, Vladimir Steshin <vladsz83@gmail.com>:
> >>>
> >>>> Vyacheslav, this is exactly what I found. I'm doing [1] (metrics for
> >>>> services) and realized I have to wrap local calls by a proxy. Is it
a
> >>>> change of public API and should come with major release only? Or we
> can
> >>>> declare usage of services without interfaces incorrect?
> >>>> [1] https://issues.apache.org/jira/browse/IGNITE-12464
> >>>>
> >>>> вт, 25 февр. 2020 г. в 16:17, Vyacheslav Daradur <daradurvs@gmail.com
> >:
> >>>>
> >>>>> {IgniteServices#service(String name)} returns direct reference in
the
> >>>>> current implementation.
> >>>>>
> >>>>> So, class casting should work for your example:
> >>>>> ((MyServiceImpl)ignite.services().service(“myService”)).bar();
> >>>>>
> >>>>> It is safer to use an interface instead of an implementation, there
> is
> >>>>> no guarantee that in future releases direct link will be returned,
a
> >>>>> service instance might be wrapped for monitoring for example.
> >>>>>
> >>>>>
> >>>>> On Tue, Feb 25, 2020 at 4:09 PM Vladimir Steshin <vladsz83@gmail.com
> >
> >>>>> wrote:
> >>>>>
> >>>>>> Vyacheslav, Hi.
> >>>>>>
> >>>>>> I see. But can we consider 'locally deployed service' is a proxy
> too,
> >>>>>> not direct reference? What if I need to wrap it? This would
be local
> >>>>>> service working via proxy or null.
> >>>>>>
> >>>>>> вт, 25 февр. 2020 г. в 16:03, Vyacheslav Daradur <
> daradurvs@gmail.com
> >>>>>> >:
> >>>>>>
> >>>>>>> Hi, Vladimir
> >>>>>>>
> >>>>>>> The answer is in API docs: "Gets *locally deployed service*
with
> >>>>>>> specified name." [1]
> >>>>>>>
> >>>>>>> That means {IgniteServices#service(String name)} returns
only
> >>>>>>> locally deployed instance or null.
> >>>>>>>
> >>>>>>> {IgniteServices#serviceProxy(…)} returns proxy to call
instances
> >>>>>>> across the cluster. Might be used for load-balancing.
> >>>>>>>
> >>>>>>> [1]
> >>>>>>>
> https://github.com/apache/ignite/blob/56975c266e7019f307bb9da42333a6db4e47365e/modules/core/src/main/java/org/apache/ignite/IgniteServices.java#L569
> >>>>>>>
> >>>>>>> On Tue, Feb 25, 2020 at 3:51 PM Vladimir Steshin <
> vladsz83@gmail.com>
> >>>>>>> wrote:
> >>>>>>>
> >>>>>>>> Hello, Igniters.
> >>>>>>>>
> >>>>>>>> Previous e-mail was with wrong topic 'daradurvs@gmail.com'
:)
> >>>>>>>>
> >>>>>>>> I got a question what exactly IgniteServices#service(String
name)
> >>>>>>>> is supposed to return: reference to the object or a
proxy for
> some reason
> >>>>>>>> like IgniteServices#serviceProxy(…)? Vyacheslav D.,
can you tell
> me your
> >>>>>>>> opinion?
> >>>>>>>>
> >>>>>>>> public interface MyService {
> >>>>>>>>
> >>>>>>>>                public void foo();
> >>>>>>>>
> >>>>>>>> }
> >>>>>>>>
> >>>>>>>> public class MyServiceImpl implements Service, MyService
{
> >>>>>>>>
> >>>>>>>>                @Override public void foo(){ … }
> >>>>>>>>
> >>>>>>>>                public void bar(){ … };
> >>>>>>>>
> >>>>>>>> }
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> // Is it required to support
> >>>>>>>>
> >>>>>>>> MyServiceImpl srvc = ignite.services().service(“myService”);
> >>>>>>>>
> >>>>>>>> srvc.foo();
> >>>>>>>>
> >>>>>>>> srvc.bar();
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> // Or is the only correct way:
> >>>>>>>>
> >>>>>>>> MyService srvc = ignite.services().service(“myService”);
> >>>>>>>>
> >>>>>>>> srvc.foo();
> >>>>>>>>
> >>>>>>>>
> >>>>>>>
> >>>>>>> --
> >>>>>>> Best Regards, Vyacheslav D.
> >>>>>>>
> >>>>>>
> >>>>>
> >>>>> --
> >>>>> Best Regards, Vyacheslav D.
> >>>>>
> >>>> --
> >>> Best Regards, Vyacheslav D.
> >>>
> >>
> >
> > --
> > Best Regards, Vyacheslav D.
> >
>

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