Re: Customizing Sample Pinger of Uima

[Florian <f....@web.de>]

Hi,

is there eventual an example or demo for sending request to individual
service instances? I couldn't find an example in the repository.

Best regards,
Florian

On Mi, Mai 1, 2019 at 12:13 AM, Eddie Epstein <ea...@gmail.com>
wrote:
> Hi Florian,
>
> Interesting questions. First, yes the intended behavior is to leave 1
> instance running. Services are either started by having
> autostart=true, or
> by a job or another service having a dependency on the service.
> Logically
> it could be possible to let a pinger stop all instances and have the
> service still be in some kind of "running" state so that the pinger
> would
> continue running and be able to restart instances when it detected a
> need;
> all that is needed is a bit of programming :)
>
> A hacky approach would be not to use autostart, rather to start
> service-A
> by using a dummy service-B with a dependency on A. When service A
> pinger
> wants to stop A, it could issue a command to stop B which would allow
> service A to be stopped. Restarting A would require an external
> program
> requesting B to be started again.
>
> For the second question, the answer is yes for UIMA-AS services. The
> latest
> version of UIMA-AS supports sending process requests to specific
> service
> instances. A pinger could send such requests, and when an instance
> fails to
> reply the pinger can direct that instance to be stopped and another
> instance started. The answer is also yes for custom services for
> which the
> pinger knows how to address each instance.
>
> Regards,
> Eddie
>
> On Tue, Apr 30, 2019 at 1:43 PM Florian <f.allgoewer@web.de
> <ma...@web.de>> wrote:
>
>>  Hello everyone,
>>
>>  I have two questions about the given sample pinger example of Uima.
>>
>>  It is possible to set the minimal numbers of instances of a service
>> to
>>  zero? If I set the min-variable to zero uima is always starting a
>> new
>>  instance, when the last one is shutdown. Is this behavior intended
>> or
>>  is there a way to prevent the start of a new instance, when there
>> is no
>>  calls to the service? As we have some services that a rarely used,
>> we
>>  would only like to start instances on demand.
>>
>>  Secondly is there also a option to call specific instances of a
>> service
>>  and restart them? We would like to do health checks for individual
>>  instances and restart them if needed.
>>
>>  Best Regards
>>
>>  Florian
>>
>>
>>
>>

Re: Customizing Sample Pinger of Uima

[Eddie Epstein <ea...@gmail.com>]

Hi Florian,

The documentation for this is at
http://uima.apache.org/d/uima-as-2.10.3/uima_async_scaleout.html#ugr.ref.async.api.usage_targetservice

There is a test case at
https://svn.apache.org/viewvc/uima/uima-as/trunk/uimaj-as-activemq/src/test/java/org/apache/uima/ee/test/TestUimaASExtended.java?revision=1826882&view=markup#l2238

Regards,
Eddie

On Mon, May 6, 2019 at 10:13 AM Florian <f....@web.de> wrote:

> Hi,
>
> is there eventual an example or demo for sending request to individual
> service instances? I couldn't find an example in the repository.
>
> Best regards,
> Florian
>
> On Mi, Mai 1, 2019 at 12:13 AM, Eddie Epstein <ea...@gmail.com>
> wrote:
> > Hi Florian,
> >
> > Interesting questions. First, yes the intended behavior is to leave 1
> > instance running. Services are either started by having
> > autostart=true, or
> > by a job or another service having a dependency on the service.
> > Logically
> > it could be possible to let a pinger stop all instances and have the
> > service still be in some kind of "running" state so that the pinger
> > would
> > continue running and be able to restart instances when it detected a
> > need;
> > all that is needed is a bit of programming :)
> >
> > A hacky approach would be not to use autostart, rather to start
> > service-A
> > by using a dummy service-B with a dependency on A. When service A
> > pinger
> > wants to stop A, it could issue a command to stop B which would allow
> > service A to be stopped. Restarting A would require an external
> > program
> > requesting B to be started again.
> >
> > For the second question, the answer is yes for UIMA-AS services. The
> > latest
> > version of UIMA-AS supports sending process requests to specific
> > service
> > instances. A pinger could send such requests, and when an instance
> > fails to
> > reply the pinger can direct that instance to be stopped and another
> > instance started. The answer is also yes for custom services for
> > which the
> > pinger knows how to address each instance.
> >
> > Regards,
> > Eddie
> >
> > On Tue, Apr 30, 2019 at 1:43 PM Florian <f.allgoewer@web.de
> > <ma...@web.de>> wrote:
> >
> >>  Hello everyone,
> >>
> >>  I have two questions about the given sample pinger example of Uima.
> >>
> >>  It is possible to set the minimal numbers of instances of a service
> >> to
> >>  zero? If I set the min-variable to zero uima is always starting a
> >> new
> >>  instance, when the last one is shutdown. Is this behavior intended
> >> or
> >>  is there a way to prevent the start of a new instance, when there
> >> is no
> >>  calls to the service? As we have some services that a rarely used,
> >> we
> >>  would only like to start instances on demand.
> >>
> >>  Secondly is there also a option to call specific instances of a
> >> service
> >>  and restart them? We would like to do health checks for individual
> >>  instances and restart them if needed.
> >>
> >>  Best Regards
> >>
> >>  Florian
> >>
> >>
> >>
> >>
>
>