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From Vyacheslav Daradur <daradu...@gmail.com>
Subject Re: Reference of local service.
Date Mon, 02 Mar 2020 08:26:10 GMT
>> 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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