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Posted to dev@sling.apache.org by Felix Meschberger <fm...@gmail.com> on 2010/04/06 12:18:24 UTC
Lazy Servlet service access
Hi all,
IMHO we have an issue with Sling's access to Servlet registered as
services and provided as Resources in the Resource tree for handling
requests:
* The Servlet services are eagerly accessed and initialized
by the Sling Engine.
* The Servlet services are eagerly accessed by the Servlet
Resolver bundle to register them as Resources.
* Initialization and use of the servlets is split between the
Sling Engine and Servlet Resolver.
I think we should change this as follows:
* All Servlet service handling is concentrated in the Servlet
Resolver.
* Servlet services are accessed on-demand only. This works
because all information to register a servlet in the
resource tree is provided as service registration properties
This allows for the registration of Servlet services as service
factories, e.g. by declaring the servlets as delayed compoents. This in
turn enables us to optimize resource consumption:
* Upon startup, the servlets need not be instantiated, only
the ServiceFactory needs to be registered.
* As a consequence class loaders creation might be delayed.
* Memory can be conserved by not creating objects which are
never used or not used often.
* Overall startup performance could be increased.
WDYT ?
Regards
Felix
Re: Lazy Servlet service access
Posted by Carsten Ziegeler <cz...@apache.org>.
Sounds good to me: +1
Carsten
Felix Meschberger wrote
> Hi all,
>
> IMHO we have an issue with Sling's access to Servlet registered as
> services and provided as Resources in the Resource tree for handling
> requests:
>
> * The Servlet services are eagerly accessed and initialized
> by the Sling Engine.
> * The Servlet services are eagerly accessed by the Servlet
> Resolver bundle to register them as Resources.
> * Initialization and use of the servlets is split between the
> Sling Engine and Servlet Resolver.
>
> I think we should change this as follows:
>
> * All Servlet service handling is concentrated in the Servlet
> Resolver.
> * Servlet services are accessed on-demand only. This works
> because all information to register a servlet in the
> resource tree is provided as service registration properties
>
> This allows for the registration of Servlet services as service
> factories, e.g. by declaring the servlets as delayed compoents. This in
> turn enables us to optimize resource consumption:
>
> * Upon startup, the servlets need not be instantiated, only
> the ServiceFactory needs to be registered.
> * As a consequence class loaders creation might be delayed.
> * Memory can be conserved by not creating objects which are
> never used or not used often.
> * Overall startup performance could be increased.
>
>
> WDYT ?
>
> Regards
> Felix
>
--
Carsten Ziegeler
cziegeler@apache.org
Re: Lazy Servlet service access
Posted by Felix Meschberger <fm...@gmail.com>.
Hi
On 06.04.2010 23:26, Ian Boston wrote:
> +1
> I suspect there may be some servlets that were being used as a surrogate for a startup configuration component, which will need to be re-factored (eg activate or init doing something not related to the servlet function), but that will be a good thing. I am assuming that initialisation becomes lazy on all servlets... is that right ?
If a Servlet service registered using Declarative Services, the
activation actually has two phases:
* activation as a component
* initialization as a Servlet
The first phase is fully controlled by the component descriptor. It may
be done eagerly (immediate component) or lazily (delayed component).
The second phase is controlled by the Servlet service consumer. Now,
this is done egerly and my goal is to do this lazily.
In the end: If initialization is done in the component's activate
method, this may still be done immediately (though I stroungly
discourage such requirements). If initialization is done in the
Servlet's init method, this will be delayed.
Regards
Felix
> I suspect there may be some servlets that were being used as a surrogate for a startup configuration component, which will need to be re-factored (eg activate or init doing something not related to the servlet function), but that will be a good thing. I am assuming that initialisation becomes lazy on all servlets... is that right ?
> Ian
>
> On 6 Apr 2010, at 20:18, Felix Meschberger wrote:
>
>> Hi all,
>>
>> IMHO we have an issue with Sling's access to Servlet registered as
>> services and provided as Resources in the Resource tree for handling
>> requests:
>>
>> * The Servlet services are eagerly accessed and initialized
>> by the Sling Engine.
>> * The Servlet services are eagerly accessed by the Servlet
>> Resolver bundle to register them as Resources.
>> * Initialization and use of the servlets is split between the
>> Sling Engine and Servlet Resolver.
>>
>> I think we should change this as follows:
>>
>> * All Servlet service handling is concentrated in the Servlet
>> Resolver.
>> * Servlet services are accessed on-demand only. This works
>> because all information to register a servlet in the
>> resource tree is provided as service registration properties
>>
>> This allows for the registration of Servlet services as service
>> factories, e.g. by declaring the servlets as delayed compoents. This in
>> turn enables us to optimize resource consumption:
>>
>> * Upon startup, the servlets need not be instantiated, only
>> the ServiceFactory needs to be registered.
>> * As a consequence class loaders creation might be delayed.
>> * Memory can be conserved by not creating objects which are
>> never used or not used often.
>> * Overall startup performance could be increased.
>>
>>
>> WDYT ?
>>
>> Regards
>> Felix
>
>
Re: Lazy Servlet service access
Posted by Ian Boston <ie...@tfd.co.uk>.
+1
I suspect there may be some servlets that were being used as a surrogate for a startup configuration component, which will need to be re-factored (eg activate or init doing something not related to the servlet function), but that will be a good thing. I am assuming that initialisation becomes lazy on all servlets... is that right ?
Ian
On 6 Apr 2010, at 20:18, Felix Meschberger wrote:
> Hi all,
>
> IMHO we have an issue with Sling's access to Servlet registered as
> services and provided as Resources in the Resource tree for handling
> requests:
>
> * The Servlet services are eagerly accessed and initialized
> by the Sling Engine.
> * The Servlet services are eagerly accessed by the Servlet
> Resolver bundle to register them as Resources.
> * Initialization and use of the servlets is split between the
> Sling Engine and Servlet Resolver.
>
> I think we should change this as follows:
>
> * All Servlet service handling is concentrated in the Servlet
> Resolver.
> * Servlet services are accessed on-demand only. This works
> because all information to register a servlet in the
> resource tree is provided as service registration properties
>
> This allows for the registration of Servlet services as service
> factories, e.g. by declaring the servlets as delayed compoents. This in
> turn enables us to optimize resource consumption:
>
> * Upon startup, the servlets need not be instantiated, only
> the ServiceFactory needs to be registered.
> * As a consequence class loaders creation might be delayed.
> * Memory can be conserved by not creating objects which are
> never used or not used often.
> * Overall startup performance could be increased.
>
>
> WDYT ?
>
> Regards
> Felix