Hi David D, The problem with registering Rule objects in the Service Registry is that it becomes a bit hard to create different adapters for different parts of the code. Maybe in bundle A you need a converter adapter that has rules X and Y and in bundle B and C you need a converter adapter that has rules Y and Z. It kind of becomes messy to specify what rules need to be picked up by what converter if we used a whiteboard pattern for the Adapter rules.
On the other hand I think it would be totally fine to create your Converter adapter somewhere based on the rules you want and then put your adapted Converters in the OSGi service registry with the properties that you define to share these adapters. Then in your consuming bundles you can select the right adapted Converter by using the right filter. I think that there is absolutely nothing 'non-standard' in that approach as you can use the Service Registry to share whatever objects you like. When you need the spec-defined converter you create a new one by calling 'new StandardConverter()' so there is a clear way to obtain a plain vanilla one versus the adapted ones. If you want to share rules across adapted converters you can do this by creating specific MyRule() classes that provide a single place to hold the rule implementations. Or you could register those Rules in the SR yourself and consume them when creating your own adapters - but then you need to make sure to select the right ones as mentioned above. Hope this helps/makes sense, David BTW this is exactly the kinds of discussions we like to have in the OSGi Expert Groups, so if you, or anyone else reading this is actually interested in taking part in these at OSGi, feel free to join the organization: http://www.osgi.org/join On 9 September 2016 at 07:01, David Daniel <david.daniel.1...@gmail.com> wrote: > Sorry, I meant Rule and not FunctionThrowsException > > On Fri, Sep 9, 2016 at 9:47 AM, David Daniel <david.daniel.1...@gmail.com> > wrote: > > > For me I don't think it is the change to new that is concerning but I am > > also concerned with the departure from the OSGI dependencies and way of > > doing things. I would prefer an implementation that does something like > > includes FunctionThrowsException from a whiteboard pattern with a > prototype > > scope to determine the standard rules in the felix implementation (I can > > understand why you are not doing this in the current implementation > because > > then it be dependent on osgi). I can see how I can expose a converter > as a > > service and add the rules I want but it would not be very standard. > > Libraries that I use for stuff like rest or something else would not use > my > > converter service. If I wanted libraries to use my converter > > implementation I would have to write my own custom converter bundle but > > then I would lose out on having a well tested bundle that is used in many > > applications. I can understand the new route but I personally prefer the > > old one and am a fan of OSGI. > > > > David Daniel > > > > On Thu, Sep 8, 2016 at 11:00 PM, David Leangen <o...@leangen.net> wrote: > > > >> > >> :-) > >> > >> “new” (or static) for non OSGi code, the usual service acquisition for > >> OSGi environments. The basic idea was to separate API from > Implementation. > >> Is that no longer the objective? > >> > >> Or, if things start to get messy, OSGi only? Why the sudden desire to > >> take a turn away from OSGi? > >> > >> Or maybe this project should not even be part of OSGi? > >> > >> I just find it a bit confusing. Am I missing something? Maybe OSGi is > >> starting to lose its way?? > >> > >> Cheers, > >> =David > >> > >> > >> > On Sep 9, 2016, at 11:51 AM, Benson Margulies <bimargul...@gmail.com> > >> wrote: > >> > > >> > And then you need 'new' for the Factory, or a static method? > Somewhere, > >> the > >> > chain of abstraction has to stop. If you don't have any parameters > that > >> > modify the creation, 'new' is just as good as any sort of Factory or > >> > Builder. > >> > > >> > On Thu, Sep 8, 2016 at 10:21 PM, David Leangen <o...@leangen.net> > >> wrote: > >> > > >> >> > >> >> Hi David B., > >> >> > >> >> Thank for your this explanation. Much of this makes sense, but again, > >> just > >> >> out of curiosity… > >> >> > >> >> I do understand the benefit of having this type of functionality > >> outside > >> >> of an OSGi environment. Perhaps the same could even be said for many > >> other > >> >> services, too, I’m not sure. > >> >> > >> >> To do that, instead of using “new” (which for me is a bit of a > shock; I > >> >> don’t recall even having used “new” to obtain a “service” from a > >> different > >> >> bundle), why not use a factory? Actually, the previous way that you > >> wrote > >> >> the util package with the publicly available Factory seems like a > good > >> >> approach to me. > >> >> > >> >> I’m not married to it, I’m just trying to understand why… Why is > “new” > >> >> better than a factory, if both achieve the same objective? > >> >> > >> >> > >> >> Cheers, > >> >> =David > >> >> > >> >> > >> >> > >> >>> On Sep 9, 2016, at 9:53 AM, David Bosschaert < > >> david.bosscha...@gmail.com> > >> >> wrote: > >> >>> > >> >>> Hi David L, > >> >>> > >> >>> Well, I have to say that I've always thought that the Converter > should > >> >> be a > >> >>> service as well, but where services really come to shine is where > you > >> >>> potentially have different implementations that might provide > >> different > >> >>> features. For the Converter there is very little room for difference > >> in > >> >>> implementations. The converters should behave exactly like the spec > >> will > >> >>> describe. Any variation on that can be added via the adapters. There > >> is > >> >>> still the possibility of distinguishing between implementations > from a > >> >>> performance point of view, but from a behavioural point of view all > >> >>> converters should behave the same to that they are entirely > >> predictable. > >> >> Of > >> >>> course, this is still possible to do with services, and there are > many > >> >>> services already of which you would only typically have one at > >> runtime. > >> >>> > >> >>> The difference here is that the converter is such a generally useful > >> >> thing, > >> >>> that it can also be really useful outside of an OSGi framework. The > >> API > >> >>> itself has no dependency on any other OSGi classes. The thinking is > >> that > >> >>> with a simple constructor this makes the converter really easy to > use > >> in > >> >>> any environment Java environment. > >> >>> > >> >>> Services are still one of the best features of OSGi IMHO, and for > the > >> >>> Serializers (what used to be called Codecs) we'll still use > services. > >> >> This > >> >>> especially makes sense since there can be more than one Serializer, > >> there > >> >>> is a lot of implementation freedom there (can support any kind of > >> format > >> >>> you like) and they are selected based on service properties. > >> >>> > >> >>> So I agree, services are generally the best choice, however in some > >> >>> specific cases, using a simple constructor (or factory method) can > >> make > >> >>> sense, especially if there is little room for variation. > >> >>> > >> >>> Cheers, > >> >>> > >> >>> David > >> >>> > >> >>> On 8 September 2016 at 16:42, David Leangen <o...@leangen.net> > wrote: > >> >>> > >> >>>> > >> >>>> Hi, > >> >>>> > >> >>>> Just out of pure curiosity… what is the reason for moving away from > >> >>>> services like this? This seems like quite a departure from the way > >> >> things > >> >>>> used to be done… > >> >>>> > >> >>>> Cheers, > >> >>>> =David > >> >>>> > >> >>>> > >> >>>> > >> >>>>> On Sep 9, 2016, at 8:14 AM, David Daniel < > >> david.daniel.1...@gmail.com> > >> >>>> wrote: > >> >>>>> > >> >>>>> Yes I understand. Thank you > >> >>>>> > >> >>>>> On Sep 8, 2016 7:10 PM, "David Bosschaert" < > >> david.bosscha...@gmail.com > >> >>> > >> >>>>> wrote: > >> >>>>> > >> >>>>>> Hi David D, > >> >>>>>> > >> >>>>>> The pattern that is being followed here is similar to what is > done > >> for > >> >>>> OSGi > >> >>>>>> Promises of which an implementation exists in Apache Aries [1]. > >> There > >> >>>> the > >> >>>>>> Deferred, a class in the org.osgi.service... namespace > instantiates > >> >> the > >> >>>>>> Aries implementation. Other implementations can replace the > >> Deferred > >> >>>> class > >> >>>>>> to instantiate their own implementations. > >> >>>>>> Similarly here constructing a new > >> >>>>>> org.osgi.service.converter.StandardConverter will instantiate > the > >> >> Felix > >> >>>>>> implementation. The org.osgi.service.converter package is > embedded > >> in > >> >>>> the > >> >>>>>> bundle. Other implementations will also embed the > >> >>>>>> org.osgi.service.converter package but provide a different > >> >>>>>> StandardConverter class, which instantiates a different > >> >> implementation. > >> >>>>>> > >> >>>>>> Changed in the recent refactoring is that the Converter is not a > >> >> service > >> >>>>>> any more. The StandardConverter is a converter instance that is > >> >> exactly > >> >>>>>> doing what it says in the spec. Anyone who wants a converter > simply > >> >>>> creates > >> >>>>>> one by calling new StandardConverter(). > >> >>>>>> If you want to add customization rules, you simply obtain an > >> Adapter > >> >> by > >> >>>>>> calling > >> >>>>>> Adapter a = new StandardConverter().newAdapter(); > >> >>>>>> Then you can add your rules to a. The Adapter a is also a > >> Converter - > >> >> it > >> >>>>>> implements the Converter interface just like the > >> StandardConverter. So > >> >>>> you > >> >>>>>> can call a.convert(something).to(SomethingElse.class) which > >> triggers > >> >>>> your > >> >>>>>> rules if applicable. > >> >>>>>> This allows you to create different adapters for different parts > of > >> >> your > >> >>>>>> application. Its up to the application to decide how to share > these > >> >>>>>> adapters with other parts of the application. You could use the > >> >> service > >> >>>>>> registry for that but that's up to you. > >> >>>>>> > >> >>>>>> Hope this helps, > >> >>>>>> > >> >>>>>> David > >> >>>>>> > >> >>>>>> [1] see https://svn.apache.org/viewvc/aries/trunk/async/ > >> >>>>>> promise-api/src/main/java/org/osgi/util/promise/Deferred. > >> >>>> java?view=markup > >> >>>>>> > >> >>>>>> On 8 September 2016 at 07:00, David Daniel < > >> >> david.daniel.1...@gmail.com > >> >>>>> > >> >>>>>> wrote: > >> >>>>>> > >> >>>>>>> I am guessing the stuff in the org.osgi.service namespace is > going > >> >>>> into a > >> >>>>>>> separate bundle similar to how the other services were taken out > >> of > >> >>>>>>> compendium. Right now the StandardConverter in source control > >> news > >> >> up > >> >>>> an > >> >>>>>>> apache impl converter object. Is that code going to change to > >> get a > >> >>>>>>> converterfactory from the service registry and get a converter > >> >> instance > >> >>>>>>> from there or something like that. The reason I am asking is > that > >> >>>> right > >> >>>>>>> now I have different bundles that add rules to the adapter for > the > >> >>>>>> objects > >> >>>>>>> that they manage. It happens one time on activate. Should I be > >> >>>> changing > >> >>>>>>> how I do things for instance, should my "Search" service have a > >> >>>> function > >> >>>>>>> that gets a converter with the rules added and inside the get > >> >> converter > >> >>>>>>> function it news up a standard converter and then adds the rules > >> or > >> >>>>>> should > >> >>>>>>> I be adding rules to some global service or adapter that > >> >>>>>> StandardConverter > >> >>>>>>> will eventually get an object from. > >> >>>>>>> > >> >>>>>>> Thanks for any help, > >> >>>>>>> David Daniel > >> >>>>>>> > >> >>>>>>> On Thu, Sep 8, 2016 at 9:30 AM, David Bosschaert < > >> >>>>>>> david.bosscha...@gmail.com > >> >>>>>>>> wrote: > >> >>>>>>> > >> >>>>>>>> Hi all, > >> >>>>>>>> > >> >>>>>>>> The Converter API was recently discussed in the OSGi Expert > >> Groups > >> >> and > >> >>>>>>>> based on the feedback the API has been refactored a bit. > >> >>>>>>>> One change is how the converter is obtained in a standard way. > >> >>>>>> Previously > >> >>>>>>>> this was done by calling ConverterFactory.standardConverter() > >> but > >> >>>> this > >> >>>>>>> is > >> >>>>>>>> now done by calling 'new StandardConverter()'. > >> >>>>>>>> The converter can be used inside an OSGi framework but also > >> outside > >> >> of > >> >>>>>>> OSGi > >> >>>>>>>> in the same way. This follows a pattern used by the OSGi > >> Promises as > >> >>>>>>> well. > >> >>>>>>>> The Codecs will remain an OSGi service (also obtainable via > >> >>>>>>>> ServiceLoader.load()) but they are renamed to 'Serializer'. > >> >>>>>>>> I've made these changes to the Felix Converter codebase. > >> >>>>>>>> > >> >>>>>>>> This is a component that is still very much under development > >> until > >> >>>> the > >> >>>>>>>> OSGi R7 specs are released so changes like this can happen. For > >> >> those > >> >>>>>> who > >> >>>>>>>> already use the convert it should not be too hard to update > their > >> >> code > >> >>>>>> - > >> >>>>>>>> hopefully :) > >> >>>>>>>> > >> >>>>>>>> Cheers, > >> >>>>>>>> > >> >>>>>>>> David > >> >>>>>>>> > >> >>>>>>> > >> >>>>>> > >> >>>> > >> >>>> > >> >> > >> >> > >> > >> > > >
