I'm getting a bit closer regarding the interceptors. Still two problems for me:
a) I still don't understand how to get hold of my intercepted instance from within my interceptor. I get a reference to a DependencyModel from which I can get a ComponentInstance. But how do I go from there to my ComponentA class. I need to access the property "extenders" in order for my interceptor to do its job. b) Also, when the property "extenders" is changed, I need to force the interceptor to recalculate the dependencies. How can I accomplish that? Getting deeper into iPojo than I've been before... /Bengt 2013/11/26 Bengt Rodehav <[email protected]> > 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] >> >> >
