Thanks Clement!
2013/11/26 Clement Escoffier <[email protected]> > Hi, > > On 25 nov. 2013, at 20:19, Bengt Rodehav <[email protected]> wrote: > > > Hello Clement and as always thanks for your detailed answer! > > > > You’re welcome. > > > It does seem a bit complicated to "require" an interceptor. Perhaps an > > easier way of doing this might be possible in the future. > > I think it would be a good addition. Thinking about it. > > > Anyway, I'm not > > exactly sure that I understood what you meant. Just to clarify: > > > > My Component A (the component to be intercepted) has the following code: > > > > @Property(name = "extenders", mandatory = false) > > private String[] mExtenderIds; > > > > @Requires(optional = true, id = "extenders") > > private IExtender[] mExtenders; > > > > Do you mean that I should put a filter on the @Requires with > id="extenders" > > (the intercepted = true) so that it can only be satisfied if my > interceptor > > has added that property? > > Exactly. > > > > > But how do I then handle the situation where my Component A does not > > require any extenders? In that case I was planning on setting the > > dependency to optional to make my instance valid without any extenders. > > > > Or, perhaps I could first set the @Requires to mandatory (with the > filter): > > > > @Requires(optional = false, id = "extenders", > filter="(intercepted=true)") > > private IExtender[] mExtenders; > > > > Then, if my interceptor sees that the instance does not require any > > extenders it can set the dependency to become optional. This way I both > > require the interceptor (via the filter) and I ensure that the only way > to > > allow the instance to be valid without the dependency is if the > interceptor > > has explicitly set the dependency to optional. > > That would work. You can change the optionality status of the dependency > from the dependency model you get in the interceptor. > > Regards, > > Clement > > > > > /Bengt > > > > > > > > > > 2013/11/25 Clement Escoffier <[email protected]> > > > >> Hi, > >> > >> > >> On 25 nov. 2013, at 11:04, Bengt Rodehav <[email protected]> wrote: > >> > >>> I've started to investigate using iPojo interceptors. I'm using iPojo > >>> version 1.11.0. I want to accomplish the following: > >>> > >>> Component A can be "extended" by specifying a list of (required) > >>> "extenders" (actually their id's), like this: > >>> > >>> @Property(name = "extenders", mandatory = false) > >>> private String[] mExtenderIds; > >>> > >>> @Requires(optional = true, id = "extenders") > >>> private IExtender[] mExtenders; > >>> > >>> > >>> The property is optional but if any extenderId's are listed then the > >>> @Requires should require that IExtender's with the corresponding > >> extenderId > >>> is started. > >>> > >>> The IExtender interface contains the following method: > >>> > >>> public String getExtenderId(); > >>> > >>> Thus, every extender has an extenderId and if that id is listed in a > >>> components "extender" property then the corresponding service should be > >>> required, otherwise not. > >>> > >>> My idea (actually Clement's idea from a previous conversation on this > >>> list). is to use a RankingInterceptor that returns an empty array until > >> all > >>> required services are present. > >>> > >>> I think this is doable but in order for my RankingInterceptor to work, > it > >>> must have access to the component's "extenders" property. It would then > >> go > >>> through all the services implementing the IExtender interface and if > >> there > >>> are extenders corresponding to the required extenderId's it would > return > >>> all of those, otherwise it would return an empty list. Also, if a list > of > >>> extenderId's was specified, then the service dependency is set to > >>> mandatory, otherwise to optional. > >>> > >>> My problem is how to gain access to the configuration property (the > >>> "extenders" property) of my component from the interceptor. How can I > do > >>> this? > >> > >> When the interceptor is hooked to a dependency, it receives the > dependency > >> model object. From this object you can retrieve the component instance > and > >> get the introspection metadata. > >> > >>> > >>> Another question I have is how to make sure that the interceptor is > >> active. > >>> If the interceptor is not active then my component could become > >> erroneously > >>> valid. Would it be feasible to have a mandatory dependency on the > >>> interceptor? > >> > >> Unfortunately not, at least not easily. What you can do is a combination > >> between a filter and two interceptors: the ranking interceptors as you > did, > >> and a tracking interceptor. Let me explain: > >> > >> Let’s imagine your consumer with your service dependency. Add a filter > >> that will be resolved only if your interceptor is there, something like: > >> (intercepted=true). > >> Your interceptor implement both tracking and ranking interceptors. When > >> the accept method is called on your interceptor, it can ‘transform’ the > >> original service reference to add the ‘intercepted’ property > >> (ref.addProperty(“intercepted”, true);) This modified service reference > >> matches your filter. Then, do your ranking policy are we discussed. > >> > >> This solution ensure that your dependency can only be resolved if your > >> interceptor is there. Indeed without the interceptor, the filter does > not > >> match. > >> > >> Regards, > >> > >> Clement > >> > >>> > >>> /Bengt > >> > >> > >> --------------------------------------------------------------------- > >> To unsubscribe, e-mail: [email protected] > >> For additional commands, e-mail: [email protected] > >> > >> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [email protected] > For additional commands, e-mail: [email protected] > >
