ipojo late injection

[Al...@miranda.com]

Hello everyone,

I am just starting with iPOJO and I was wondering what is the 
right/recommended way in iPOJO to select a service late at runtime. 
Imagine a textbox in a GUI that asks for a version and only after the user 
entered version=1.3.5 I can know that the service I want injected is 
v1.3.5. In this case annotations or xml don't work since they are static

What I am currently doing is using an aggregate dependency and then I loop 
myself over all the services (the version is a property of the service 
BTW) and return the one that matches the request

I though of multiple ways of doing this but I don't know if they are 
possible or make sense

1) doing some kind of service registry query where I can explicitly ask 
for the service with the given properties and I will have it returned 
right away
2) modifying the injection filter at runtime; however with this technique 
I would have to wait for the framework to do the injection whenever it 
wants instead of when I need it. i.e. it is asynchronous
3) using the iPOJO API to modify the dependency. Again this solution would 
be async
4) The one I mentioned first. Keep a list of all the services via an 
aggregate dependency and loop through them to find the one that matches
5) other?

Thank you in advance,

Alejandro Endo | Software Designer/Concepteur de logiciels

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Re: ipojo late injection

[Clement Escoffier <cl...@gmail.com>]

Hi,

There are a couple of ways to do what you want to do:

1) using a contextual filter and a context source

You can write a filter using a variable such as (version=${user.version}). Then you implement a context-source service (http://felix.apache.org/ipojo/api/1.11.0/src-html/org/apache/felix/ipojo/ContextSource.html#line.29) that provides the required variable and notifies listeners when this one changes. I would recommend to use a default value such as in (|(version=${user.version})(version=generic)).

2) Using the iPOJO reconfiguration mechanism

You can change the filter of an instance using it’s ‘Architecture’ service:
    // Retrieve the architecture of your instance
    @Requires(filter="(instance.name=my-instance)")
    Architecture architecture;
    
    public void reconfigure() {
        // Gets the dependency handler
        DependencyHandlerDescription description = (DependencyHandlerDescription) 
                architecture.getInstanceDescription().getHandlerDescription("org.apache.felix.ipojo:dependency");
        // Select your dependency
        DependencyDescription dependency = description.getDependencies()[0];
        // Set the filter
        dependency.getDependency().setFilter(filter);
    }

3) Using tracking or ranking interceptors

In iPOJO1.11.x, we have introduced service binding interceptors that can refine the service selection and ranking without changing the component code.
http://felix.apache.org/documentation/subprojects/apache-felix-ipojo/apache-felix-ipojo-userguide/ipojo-advanced-topics/service-binding-interceptors.html

In you case, I would recommend a ranking interceptor which move the service matching the user requirement first:

So, now you just have to pick a solution !

Clement

PS: Richard’s suggestion also works. It is very close to the solution #2, but requires the deployment of another bundle.

On 26 mars 2014, at 21:37, Alejandro.Endo@miranda.com wrote:

> Hello everyone,
> 
> I am just starting with iPOJO and I was wondering what is the 
> right/recommended way in iPOJO to select a service late at runtime. 
> Imagine a textbox in a GUI that asks for a version and only after the user 
> entered version=1.3.5 I can know that the service I want injected is 
> v1.3.5. In this case annotations or xml don't work since they are static
> 
> What I am currently doing is using an aggregate dependency and then I loop 
> myself over all the services (the version is a property of the service 
> BTW) and return the one that matches the request
> 
> I though of multiple ways of doing this but I don't know if they are 
> possible or make sense
> 
> 1) doing some kind of service registry query where I can explicitly ask 
> for the service with the given properties and I will have it returned 
> right away
> 2) modifying the injection filter at runtime; however with this technique 
> I would have to wait for the framework to do the injection whenever it 
> wants instead of when I need it. i.e. it is asynchronous
> 3) using the iPOJO API to modify the dependency. Again this solution would 
> be async
> 4) The one I mentioned first. Keep a list of all the services via an 
> aggregate dependency and loop through them to find the one that matches
> 5) other?
> 
> Thank you in advance,
> 
> Alejandro Endo | Software Designer/Concepteur de logiciels
> 
> DISCLAIMER:
> Privileged and/or Confidential information may be contained in this
> message. If you are not the addressee of this message, you may not
> copy, use or deliver this message to anyone. In such event, you
> should destroy the message and kindly notify the sender by reply
> e-mail. It is understood that opinions or conclusions that do not
> relate to the official business of the company are neither given
> nor endorsed by the company.
> Thank You.

Re: ipojo late injection

["Richard S. Hall" <he...@ungoverned.org>]

I'm guessing you'd want to use iPOJO API, which allows you to describe a 
component dynamically:

http://felix.apache.org/documentation/subprojects/apache-felix-ipojo/apache-felix-ipojo-userguide/apache-felix-ipojo-api.html

-> richard

On 3/26/14, 16:37 , Alejandro.Endo@miranda.com wrote:
> Hello everyone,
>
> I am just starting with iPOJO and I was wondering what is the
> right/recommended way in iPOJO to select a service late at runtime.
> Imagine a textbox in a GUI that asks for a version and only after the user
> entered version=1.3.5 I can know that the service I want injected is
> v1.3.5. In this case annotations or xml don't work since they are static
>
> What I am currently doing is using an aggregate dependency and then I loop
> myself over all the services (the version is a property of the service
> BTW) and return the one that matches the request
>
> I though of multiple ways of doing this but I don't know if they are
> possible or make sense
>
> 1) doing some kind of service registry query where I can explicitly ask
> for the service with the given properties and I will have it returned
> right away
> 2) modifying the injection filter at runtime; however with this technique
> I would have to wait for the framework to do the injection whenever it
> wants instead of when I need it. i.e. it is asynchronous
> 3) using the iPOJO API to modify the dependency. Again this solution would
> be async
> 4) The one I mentioned first. Keep a list of all the services via an
> aggregate dependency and loop through them to find the one that matches
> 5) other?
>
> Thank you in advance,
>
> Alejandro Endo | Software Designer/Concepteur de logiciels
>
> DISCLAIMER:
> Privileged and/or Confidential information may be contained in this
> message. If you are not the addressee of this message, you may not
> copy, use or deliver this message to anyone. In such event, you
> should destroy the message and kindly notify the sender by reply
> e-mail. It is understood that opinions or conclusions that do not
> relate to the official business of the company are neither given
> nor endorsed by the company.
> Thank You.
>


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