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, [email protected] 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
>
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