Re: [osgi-dev] Disposing component instances

[Alain Picard via osgi-dev]

Thanks Raymond

On Sun, Nov 25, 2018, 6:58 PM Raymond Auge  Please note that up to a couple of weeks ago there was a bug in Felix SCR
> managing indirect component prototype instances.
>
> https://issues.apache.org/jira/browse/FELIX-5974
>
> So you may want to make sure you have the latest.
>
> - Ray
>
> On Sun, Nov 25, 2018, 08:21 Alain Picard via osgi-dev <
> osgi-dev@mail.osgi.org wrote:
>
>> On Sun, Nov 25, 2018 at 7:50 AM Tim Ward  wrote:
>>
>>> If your DS component ‘X’ is injected with a Component Service Objects
>>> which it uses to get instances ‘A’, ‘B’ and ‘C' of a referenced service
>>> then those service instances will be released when either:
>>>
>>>
>>>- The component ‘X’ releases them by calling ungetService on the
>>>component service objects
>>>
>>> or
>>>
>>>- The component ‘X’ is deactivated (for whatever reason) at which
>>>point the Service Component Runtime will automatically release any
>>>remaining instances that haven’t been released by the component before 
>>> the
>>>end of any deactivate method.
>>>
>>>
>>> This is why the ComponentServiceObjects is a better choice than using a
>>> ServiceObjects directly, as the ServiceObjects won’t clean up after you.
>>>
>>> Can I interpret this and your previous comment as meaning that within a
>>> prototype scope component, a prototype required scope reference doesn't
>>> need to be "unget" manually and it is just the most outer invocation that
>>> should perform the “unget"
>>>
>>>
>>> In a limited way, yes. If you get many instances over the lifetime of
>>> your component ‘X’ then you should probably have a mechanism to unget them
>>> manually, otherwise the memory usage of your component will grow and grow
>>> over time (until it is deactivated). If you get two or three instances of
>>> the prototype service which you then hold for the life of the component ‘X’
>>> then feel free to let DS do all the work.
>>>
>> This is for a composing a UI view which itself has a defined lifespan,
>> but this prototype component creates a number of other prototype scoped
>> components and it would be much easier to such unget the view and not all
>> its parts.
>>
>> Small slant to this question, let's say that X has a reference to Factory
>> A (standard component) and that factory A returns a prototype scoped
>> instance, will ungetting X, release the instance returned by factory A?
>>
>> Alain
>>
>>
>>
>>> Tim
>>>
>>> On 25 Nov 2018, at 12:41, Alain Picard  wrote:
>>>
>>> Tim,
>>>
>>> Circling back on this. Re-reading section 112.3.6 it says "This means
>>> that if a component instance used a Component Service Objects object to
>>> obtain service objects, SCR must track those service objects so that when
>>> the service becomes unbound, SCR can unget any unreleased service objects".
>>>
>>> Can I interpret this and your previous comment as meaning that within a
>>> prototype scope component, a prototype required scope reference doesn't
>>> need to be "unget" manually and it is just the most outer invocation that
>>> should perform the "unget"
>>>
>>> Thanks
>>> Alain
>>>
>>> On Thu, Aug 23, 2018 at 9:20 AM Tim Ward  wrote:
>>>
 If you’re using Declarative Services to consume these other dynamic
 references then there is no need to worry. If you’re trying to
 programmatically write a prototype scoped service that has service
 dependencies then stop and use DS instead. Trying to correctly manage the
 “unget” chains that need to occur when one service in a dependency tree is
 unregistered is just too hard to be worthwhile. Tools like the
 ServiceTracker can make it tractable, but it still leaves you writing huge
 quantities of messy lifecycle code that’s a nightmare to debug.

 Also, you are correct that you must not keep using a service instance
 when the service has been unregistered. It is your job to discard that
 reference :).

 Tim

 On 23 Aug 2018, at 13:31, Alain Picard  wrote:

 Just a small note, I should have stated that my worry is about the
 unget timing. I obviously have a reference to the object and this won't
 disappear by itself, but if that service has other dynamic references that
 go away and I keep using the service, I might be in trouble. But I guess
 the template that I used already had a bit that issue with the supplier
 (which we seldom use).

 Alain

 On Thu, Aug 23, 2018 at 7:43 AM Alain Picard 
 wrote:

> Tim,
>
> Based on your referenced javadoc, some more googling, I used and
> adapted from our own current tracker and supplier to create some Prototype
> versions. Tests are showing correct results, but this is not directly 
> using
> the PrototypeServiceFactory, so I would appreciate a very quick
> confirmation that I'm not missing anything.
>
> Thanks
>
> Alain
>
>
> On Wed, Aug 22, 2018 at 11:54 AM Alain Picard 
> wrote:

Re: [osgi-dev] Disposing component instances

[Raymond Auge via osgi-dev]

Please note that up to a couple of weeks ago there was a bug in Felix SCR
managing indirect component prototype instances.

https://issues.apache.org/jira/browse/FELIX-5974

So you may want to make sure you have the latest.

- Ray

On Sun, Nov 25, 2018, 08:21 Alain Picard via osgi-dev <
osgi-dev@mail.osgi.org wrote:

> On Sun, Nov 25, 2018 at 7:50 AM Tim Ward  wrote:
>
>> If your DS component ‘X’ is injected with a Component Service Objects
>> which it uses to get instances ‘A’, ‘B’ and ‘C' of a referenced service
>> then those service instances will be released when either:
>>
>>
>>- The component ‘X’ releases them by calling ungetService on the
>>component service objects
>>
>> or
>>
>>- The component ‘X’ is deactivated (for whatever reason) at which
>>point the Service Component Runtime will automatically release any
>>remaining instances that haven’t been released by the component before the
>>end of any deactivate method.
>>
>>
>> This is why the ComponentServiceObjects is a better choice than using a
>> ServiceObjects directly, as the ServiceObjects won’t clean up after you.
>>
>> Can I interpret this and your previous comment as meaning that within a
>> prototype scope component, a prototype required scope reference doesn't
>> need to be "unget" manually and it is just the most outer invocation that
>> should perform the “unget"
>>
>>
>> In a limited way, yes. If you get many instances over the lifetime of
>> your component ‘X’ then you should probably have a mechanism to unget them
>> manually, otherwise the memory usage of your component will grow and grow
>> over time (until it is deactivated). If you get two or three instances of
>> the prototype service which you then hold for the life of the component ‘X’
>> then feel free to let DS do all the work.
>>
> This is for a composing a UI view which itself has a defined lifespan, but
> this prototype component creates a number of other prototype scoped
> components and it would be much easier to such unget the view and not all
> its parts.
>
> Small slant to this question, let's say that X has a reference to Factory
> A (standard component) and that factory A returns a prototype scoped
> instance, will ungetting X, release the instance returned by factory A?
>
> Alain
>
>
>
>> Tim
>>
>> On 25 Nov 2018, at 12:41, Alain Picard  wrote:
>>
>> Tim,
>>
>> Circling back on this. Re-reading section 112.3.6 it says "This means
>> that if a component instance used a Component Service Objects object to
>> obtain service objects, SCR must track those service objects so that when
>> the service becomes unbound, SCR can unget any unreleased service objects".
>>
>> Can I interpret this and your previous comment as meaning that within a
>> prototype scope component, a prototype required scope reference doesn't
>> need to be "unget" manually and it is just the most outer invocation that
>> should perform the "unget"
>>
>> Thanks
>> Alain
>>
>> On Thu, Aug 23, 2018 at 9:20 AM Tim Ward  wrote:
>>
>>> If you’re using Declarative Services to consume these other dynamic
>>> references then there is no need to worry. If you’re trying to
>>> programmatically write a prototype scoped service that has service
>>> dependencies then stop and use DS instead. Trying to correctly manage the
>>> “unget” chains that need to occur when one service in a dependency tree is
>>> unregistered is just too hard to be worthwhile. Tools like the
>>> ServiceTracker can make it tractable, but it still leaves you writing huge
>>> quantities of messy lifecycle code that’s a nightmare to debug.
>>>
>>> Also, you are correct that you must not keep using a service instance
>>> when the service has been unregistered. It is your job to discard that
>>> reference :).
>>>
>>> Tim
>>>
>>> On 23 Aug 2018, at 13:31, Alain Picard  wrote:
>>>
>>> Just a small note, I should have stated that my worry is about the unget
>>> timing. I obviously have a reference to the object and this won't disappear
>>> by itself, but if that service has other dynamic references that go away
>>> and I keep using the service, I might be in trouble. But I guess the
>>> template that I used already had a bit that issue with the supplier (which
>>> we seldom use).
>>>
>>> Alain
>>>
>>> On Thu, Aug 23, 2018 at 7:43 AM Alain Picard 
>>> wrote:
>>>
 Tim,

 Based on your referenced javadoc, some more googling, I used and
 adapted from our own current tracker and supplier to create some Prototype
 versions. Tests are showing correct results, but this is not directly using
 the PrototypeServiceFactory, so I would appreciate a very quick
 confirmation that I'm not missing anything.

 Thanks

 Alain


 On Wed, Aug 22, 2018 at 11:54 AM Alain Picard 
 wrote:

> Thanks! I actually saw that being called by ComponentServiceObjects
> while perusing the code.
>
> Alain
>
>
> On Wed, Aug 22, 2018 at 11:52 AM Tim Ward 
> wrote:

Re: [osgi-dev] Disposing component instances

[Tim Ward via osgi-dev]

> Small slant to this question, let's say that X has a reference to Factory A 
> (standard component) and that factory A returns a prototype scoped instance, 
> will ungetting X, release the instance returned by factory A?

The simple answer is yes, the in depth answer is “not always” due to the 
specific terms you have used in your question. 

Assuming that you are the only person who got X then it will be deactivated 
when you unget, releasing the instance from factory A. If something else is 
keeping the instance of X alive (e.g. a second user of the Singleton component 
X) then the instance of Factory A will remain alive until X is deactivated.

I hope this makes sense,

Tim

Sent from my iPhone

> On 25 Nov 2018, at 13:20, Alain Picard  wrote:
> 
>> On Sun, Nov 25, 2018 at 7:50 AM Tim Ward  wrote:
>> If your DS component ‘X’ is injected with a Component Service Objects which 
>> it uses to get instances ‘A’, ‘B’ and ‘C' of a referenced service then those 
>> service instances will be released when either:
>> 
>> The component ‘X’ releases them by calling ungetService on the component 
>> service objects
>> or
>> The component ‘X’ is deactivated (for whatever reason) at which point the 
>> Service Component Runtime will automatically release any remaining instances 
>> that haven’t been released by the component before the end of any deactivate 
>> method.
>> 
>> This is why the ComponentServiceObjects is a better choice than using a 
>> ServiceObjects directly, as the ServiceObjects won’t clean up after you.
>> 
>>> Can I interpret this and your previous comment as meaning that within a 
>>> prototype scope component, a prototype required scope reference doesn't 
>>> need to be "unget" manually and it is just the most outer invocation that 
>>> should perform the “unget"
>> 
>> In a limited way, yes. If you get many instances over the lifetime of your 
>> component ‘X’ then you should probably have a mechanism to unget them 
>> manually, otherwise the memory usage of your component will grow and grow 
>> over time (until it is deactivated). If you get two or three instances of 
>> the prototype service which you then hold for the life of the component ‘X’ 
>> then feel free to let DS do all the work.
> This is for a composing a UI view which itself has a defined lifespan, but 
> this prototype component creates a number of other prototype scoped 
> components and it would be much easier to such unget the view and not all its 
> parts.
> 
> Small slant to this question, let's say that X has a reference to Factory A 
> (standard component) and that factory A returns a prototype scoped instance, 
> will ungetting X, release the instance returned by factory A?
> 
> Alain
> 
>  
>> Tim
>> 
>>> On 25 Nov 2018, at 12:41, Alain Picard  wrote:
>>> 
>>> Tim,
>>> 
>>> Circling back on this. Re-reading section 112.3.6 it says "This means that 
>>> if a component instance used a Component Service Objects object to obtain 
>>> service objects, SCR must track those service objects so that when the 
>>> service becomes unbound, SCR can unget any unreleased service objects".
>>> 
>>> Can I interpret this and your previous comment as meaning that within a 
>>> prototype scope component, a prototype required scope reference doesn't 
>>> need to be "unget" manually and it is just the most outer invocation that 
>>> should perform the "unget"
>>> 
>>> Thanks
>>> Alain
>>> 
 On Thu, Aug 23, 2018 at 9:20 AM Tim Ward  wrote:
 If you’re using Declarative Services to consume these other dynamic 
 references then there is no need to worry. If you’re trying to 
 programmatically write a prototype scoped service that has service 
 dependencies then stop and use DS instead. Trying to correctly manage the 
 “unget” chains that need to occur when one service in a dependency tree is 
 unregistered is just too hard to be worthwhile. Tools like the 
 ServiceTracker can make it tractable, but it still leaves you writing huge 
 quantities of messy lifecycle code that’s a nightmare to debug.
 
 Also, you are correct that you must not keep using a service instance when 
 the service has been unregistered. It is your job to discard that 
 reference :).
 
 Tim
 
> On 23 Aug 2018, at 13:31, Alain Picard  wrote:
> 
> Just a small note, I should have stated that my worry is about the unget 
> timing. I obviously have a reference to the object and this won't 
> disappear by itself, but if that service has other dynamic references 
> that go away and I keep using the service, I might be in trouble. But I 
> guess the template that I used already had a bit that issue with the 
> supplier (which we seldom use).
> 
> Alain
> 
>> On Thu, Aug 23, 2018 at 7:43 AM Alain Picard  
>> wrote:
>> Tim,
>> 
>> Based on your referenced javadoc, some more googling, I used and adapted 
>> from our own current tracker and supplier to 

Re: [osgi-dev] Disposing component instances

[Alain Picard via osgi-dev]

On Sun, Nov 25, 2018 at 7:50 AM Tim Ward  wrote:

> If your DS component ‘X’ is injected with a Component Service Objects
> which it uses to get instances ‘A’, ‘B’ and ‘C' of a referenced service
> then those service instances will be released when either:
>
>
>- The component ‘X’ releases them by calling ungetService on the
>component service objects
>
> or
>
>- The component ‘X’ is deactivated (for whatever reason) at which
>point the Service Component Runtime will automatically release any
>remaining instances that haven’t been released by the component before the
>end of any deactivate method.
>
>
> This is why the ComponentServiceObjects is a better choice than using a
> ServiceObjects directly, as the ServiceObjects won’t clean up after you.
>
> Can I interpret this and your previous comment as meaning that within a
> prototype scope component, a prototype required scope reference doesn't
> need to be "unget" manually and it is just the most outer invocation that
> should perform the “unget"
>
>
> In a limited way, yes. If you get many instances over the lifetime of your
> component ‘X’ then you should probably have a mechanism to unget them
> manually, otherwise the memory usage of your component will grow and grow
> over time (until it is deactivated). If you get two or three instances of
> the prototype service which you then hold for the life of the component ‘X’
> then feel free to let DS do all the work.
>
This is for a composing a UI view which itself has a defined lifespan, but
this prototype component creates a number of other prototype scoped
components and it would be much easier to such unget the view and not all
its parts.

Small slant to this question, let's say that X has a reference to Factory A
(standard component) and that factory A returns a prototype scoped
instance, will ungetting X, release the instance returned by factory A?

Alain



> Tim
>
> On 25 Nov 2018, at 12:41, Alain Picard  wrote:
>
> Tim,
>
> Circling back on this. Re-reading section 112.3.6 it says "This means that
> if a component instance used a Component Service Objects object to obtain
> service objects, SCR must track those service objects so that when the
> service becomes unbound, SCR can unget any unreleased service objects".
>
> Can I interpret this and your previous comment as meaning that within a
> prototype scope component, a prototype required scope reference doesn't
> need to be "unget" manually and it is just the most outer invocation that
> should perform the "unget"
>
> Thanks
> Alain
>
> On Thu, Aug 23, 2018 at 9:20 AM Tim Ward  wrote:
>
>> If you’re using Declarative Services to consume these other dynamic
>> references then there is no need to worry. If you’re trying to
>> programmatically write a prototype scoped service that has service
>> dependencies then stop and use DS instead. Trying to correctly manage the
>> “unget” chains that need to occur when one service in a dependency tree is
>> unregistered is just too hard to be worthwhile. Tools like the
>> ServiceTracker can make it tractable, but it still leaves you writing huge
>> quantities of messy lifecycle code that’s a nightmare to debug.
>>
>> Also, you are correct that you must not keep using a service instance
>> when the service has been unregistered. It is your job to discard that
>> reference :).
>>
>> Tim
>>
>> On 23 Aug 2018, at 13:31, Alain Picard  wrote:
>>
>> Just a small note, I should have stated that my worry is about the unget
>> timing. I obviously have a reference to the object and this won't disappear
>> by itself, but if that service has other dynamic references that go away
>> and I keep using the service, I might be in trouble. But I guess the
>> template that I used already had a bit that issue with the supplier (which
>> we seldom use).
>>
>> Alain
>>
>> On Thu, Aug 23, 2018 at 7:43 AM Alain Picard 
>> wrote:
>>
>>> Tim,
>>>
>>> Based on your referenced javadoc, some more googling, I used and adapted
>>> from our own current tracker and supplier to create some Prototype
>>> versions. Tests are showing correct results, but this is not directly using
>>> the PrototypeServiceFactory, so I would appreciate a very quick
>>> confirmation that I'm not missing anything.
>>>
>>> Thanks
>>>
>>> Alain
>>>
>>>
>>> On Wed, Aug 22, 2018 at 11:54 AM Alain Picard 
>>> wrote:
>>>
 Thanks! I actually saw that being called by ComponentServiceObjects
 while perusing the code.

 Alain


 On Wed, Aug 22, 2018 at 11:52 AM Tim Ward  wrote:

> Registering a prototype service is almost as easy as registering a
> singleton service. Instead of registering a single object you register an
> instance of PrototypeServiceFactory
> .
> This will get called by the framework to get and release instances as
> needed.
>
> Tim
>
> On 22 Aug 2018, at 16:49, Alain Picard  wrote:

Re: [osgi-dev] Disposing component instances

[Tim Ward via osgi-dev]

If your DS component ‘X’ is injected with a Component Service Objects which it 
uses to get instances ‘A’, ‘B’ and ‘C' of a referenced service then those 
service instances will be released when either:

The component ‘X’ releases them by calling ungetService on the component 
service objects
or
The component ‘X’ is deactivated (for whatever reason) at which point the 
Service Component Runtime will automatically release any remaining instances 
that haven’t been released by the component before the end of any deactivate 
method.

This is why the ComponentServiceObjects is a better choice than using a 
ServiceObjects directly, as the ServiceObjects won’t clean up after you.

> Can I interpret this and your previous comment as meaning that within a 
> prototype scope component, a prototype required scope reference doesn't need 
> to be "unget" manually and it is just the most outer invocation that should 
> perform the “unget"

In a limited way, yes. If you get many instances over the lifetime of your 
component ‘X’ then you should probably have a mechanism to unget them manually, 
otherwise the memory usage of your component will grow and grow over time 
(until it is deactivated). If you get two or three instances of the prototype 
service which you then hold for the life of the component ‘X’ then feel free to 
let DS do all the work.

Tim

> On 25 Nov 2018, at 12:41, Alain Picard  wrote:
> 
> Tim,
> 
> Circling back on this. Re-reading section 112.3.6 it says "This means that if 
> a component instance used a Component Service Objects object to obtain 
> service objects, SCR must track those service objects so that when the 
> service becomes unbound, SCR can unget any unreleased service objects".
> 
> Can I interpret this and your previous comment as meaning that within a 
> prototype scope component, a prototype required scope reference doesn't need 
> to be "unget" manually and it is just the most outer invocation that should 
> perform the "unget"
> 
> Thanks
> Alain
> 
> On Thu, Aug 23, 2018 at 9:20 AM Tim Ward  > wrote:
> If you’re using Declarative Services to consume these other dynamic 
> references then there is no need to worry. If you’re trying to 
> programmatically write a prototype scoped service that has service 
> dependencies then stop and use DS instead. Trying to correctly manage the 
> “unget” chains that need to occur when one service in a dependency tree is 
> unregistered is just too hard to be worthwhile. Tools like the ServiceTracker 
> can make it tractable, but it still leaves you writing huge quantities of 
> messy lifecycle code that’s a nightmare to debug.
> 
> Also, you are correct that you must not keep using a service instance when 
> the service has been unregistered. It is your job to discard that reference 
> :).
> 
> Tim
> 
>> On 23 Aug 2018, at 13:31, Alain Picard > > wrote:
>> 
>> Just a small note, I should have stated that my worry is about the unget 
>> timing. I obviously have a reference to the object and this won't disappear 
>> by itself, but if that service has other dynamic references that go away and 
>> I keep using the service, I might be in trouble. But I guess the template 
>> that I used already had a bit that issue with the supplier (which we seldom 
>> use).
>> 
>> Alain
>> 
>> On Thu, Aug 23, 2018 at 7:43 AM Alain Picard > > wrote:
>> Tim,
>> 
>> Based on your referenced javadoc, some more googling, I used and adapted 
>> from our own current tracker and supplier to create some Prototype versions. 
>> Tests are showing correct results, but this is not directly using the 
>> PrototypeServiceFactory, so I would appreciate a very quick confirmation 
>> that I'm not missing anything.
>> 
>> Thanks
>> 
>> Alain
>> 
>> 
>> On Wed, Aug 22, 2018 at 11:54 AM Alain Picard > > wrote:
>> Thanks! I actually saw that being called by ComponentServiceObjects while 
>> perusing the code.
>> 
>> Alain
>> 
>> 
>> On Wed, Aug 22, 2018 at 11:52 AM Tim Ward > > wrote:
>> Registering a prototype service is almost as easy as registering a singleton 
>> service. Instead of registering a single object you register an instance of 
>> PrototypeServiceFactory 
>> .
>>  This will get called by the framework to get and release instances as 
>> needed.
>> 
>> Tim
>> 
>>> On 22 Aug 2018, at 16:49, Alain Picard >> > wrote:
>>> 
>>> Tim,
>>> 
>>> This helps quite a bit and clarifies a few points for me. As someone who is 
>>> migrating from a pre-DS environment and dealing with lots of legacy, how 
>>> can prototype scoped services be used outside of DS? That would be 
>>> fantastic. Right now we have a good solution to use singleton services 
>>> outside of DS but not for "factory" type services.
>>> 
>>> Thanks
>>> Alain
>>> 

Re: [osgi-dev] Disposing component instances

[Alain Picard via osgi-dev]

Tim,

Circling back on this. Re-reading section 112.3.6 it says "This means that
if a component instance used a Component Service Objects object to obtain
service objects, SCR must track those service objects so that when the
service becomes unbound, SCR can unget any unreleased service objects".

Can I interpret this and your previous comment as meaning that within a
prototype scope component, a prototype required scope reference doesn't
need to be "unget" manually and it is just the most outer invocation that
should perform the "unget"

Thanks
Alain

On Thu, Aug 23, 2018 at 9:20 AM Tim Ward  wrote:

> If you’re using Declarative Services to consume these other dynamic
> references then there is no need to worry. If you’re trying to
> programmatically write a prototype scoped service that has service
> dependencies then stop and use DS instead. Trying to correctly manage the
> “unget” chains that need to occur when one service in a dependency tree is
> unregistered is just too hard to be worthwhile. Tools like the
> ServiceTracker can make it tractable, but it still leaves you writing huge
> quantities of messy lifecycle code that’s a nightmare to debug.
>
> Also, you are correct that you must not keep using a service instance when
> the service has been unregistered. It is your job to discard that reference
> :).
>
> Tim
>
> On 23 Aug 2018, at 13:31, Alain Picard  wrote:
>
> Just a small note, I should have stated that my worry is about the unget
> timing. I obviously have a reference to the object and this won't disappear
> by itself, but if that service has other dynamic references that go away
> and I keep using the service, I might be in trouble. But I guess the
> template that I used already had a bit that issue with the supplier (which
> we seldom use).
>
> Alain
>
> On Thu, Aug 23, 2018 at 7:43 AM Alain Picard 
> wrote:
>
>> Tim,
>>
>> Based on your referenced javadoc, some more googling, I used and adapted
>> from our own current tracker and supplier to create some Prototype
>> versions. Tests are showing correct results, but this is not directly using
>> the PrototypeServiceFactory, so I would appreciate a very quick
>> confirmation that I'm not missing anything.
>>
>> Thanks
>>
>> Alain
>>
>>
>> On Wed, Aug 22, 2018 at 11:54 AM Alain Picard 
>> wrote:
>>
>>> Thanks! I actually saw that being called by ComponentServiceObjects
>>> while perusing the code.
>>>
>>> Alain
>>>
>>>
>>> On Wed, Aug 22, 2018 at 11:52 AM Tim Ward  wrote:
>>>
 Registering a prototype service is almost as easy as registering a
 singleton service. Instead of registering a single object you register an
 instance of PrototypeServiceFactory
 .
 This will get called by the framework to get and release instances as
 needed.

 Tim

 On 22 Aug 2018, at 16:49, Alain Picard  wrote:

 Tim,

 This helps quite a bit and clarifies a few points for me. As someone
 who is migrating from a pre-DS environment and dealing with lots of legacy,
 how can prototype scoped services be used outside of DS? That would be
 fantastic. Right now we have a good solution to use singleton services
 outside of DS but not for "factory" type services.

 Thanks
 Alain


 On Wed, Aug 22, 2018 at 11:27 AM Tim Ward  wrote:

> Hi Alain,
>
> A "Prototype scoped" service is one where the client(s) can request an
> arbitrary number of instances of the “same” service, whereas a
> ComponentFactory is a mechanism for the clients to request an arbitrary
> number of differently configured component instances.
>
> From the perspective of the component the key difference is that all
> of the instances of a prototype scoped component have the same component
> properties, and the instances created by the factory component have the
> combination of these component properties *plus* the properties passed to
> the factory.
>
> In some senses prototype scoped services are better because they:
>
>
>- Don’t require the service implementation to use DS (they may
>wish to use something else)
>- Will have satisfied references and configurations (component
>factories can be given configuration which invalidates the registration
>resulting in an error)
>
>
> The main reason that you would use a Component Factory rather than a
> prototype scoped service is if you genuinely want to have different
> specialised configurations for each instance, and it doesn’t make sense to
> use a managed service factory (i.e. the customised instances are only
> interesting to one client, or must not be shared for some reason).
>
> If your instances are identically configured (or can be, with an init
> later) then a ComponentServiceObjects getService() call should be all you
>