On Tue, Jul 28, 2009 at 5:35 PM, Richard S. Hall<[email protected]> wrote: > On 7/28/09 12:21 PM, David Savage wrote: >> >> On Tue, Jul 28, 2009 at 3:34 PM, Richard S. Hall<[email protected]> >> wrote: >> >>> >>> On 7/28/09 9:47 AM, David Savage wrote: >>> >>>> >>>> On Mon, Jul 27, 2009 at 4:03 PM, Richard S. Hall<[email protected]> >>>> wrote: >>>> >>>> >>>>> >>>>> On 7/27/09 8:24 AM, David Savage wrote: >>>>> >>>>> >>>>>> >>>>>> On Fri, Jul 24, 2009 at 11:23 PM, Richard S. >>>>>> Hall<[email protected]> >>>>>> wrote: >>>>>> >>>>>> >>>>>> >>>>>>> >>>>>>> On 7/24/09 12:35 PM, David Savage wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>>> >>>>>>>> To lay my cards on the table, I kinda like resolve=compile as it >>>>>>>> dove >>>>>>>> tails kinda neatly with resolution=optional, but equally it seems >>>>>>>> kinda bizarre to be adding another dimension to this whole problem >>>>>>>> when people are worried about the complexity of OSGi. If there is a >>>>>>>> way to do this without exposing developers to it that would be >>>>>>>> /great/ >>>>>>>> but as with OSGi I don't think we should worry about doing the right >>>>>>>> thing at the base layer IDE tools and other schemes can always >>>>>>>> simpilify this whole space down again to joe blogs. I guess it's a >>>>>>>> question of what is "right". >>>>>>>> >>>>>>>> So I guess the end result of this email is, what are your thoughts? >>>>>>>> >>>>>>>> * Is resolve=compile a good idea? >>>>>>>> * Should it be resolution=compile? >>>>>>>> * Any other options? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> Isn't this some form of "uses" constraint? Middle exposes Top because >>>>>>> it >>>>>>> inherits from it, so if you follow transitive "uses" constraints you >>>>>>> could >>>>>>> possibly assume that compile-time access is needed. >>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>>> Hmmm you're right it certainly resembles uses - should have spotted >>>>>> that myself. However I have a feeling it may get a bit hairy in >>>>>> certain edge cases, i.e. Top may not be in an exported package which >>>>>> could work at runtime I believe, as Middle would provide the class >>>>>> path to Top? >>>>>> >>>>>> >>>>>> >>>>> >>>>> I agree, it might not work in every case, but it seems like a good >>>>> place >>>>> to >>>>> start. It seems in the general case, if a type is exposed, then someone >>>>> must >>>>> have a dependency on it or contain it somewhere in the transitive set >>>>> of >>>>> dependencies, otherwise it couldn't be exposed... >>>>> >>>>> >>>> >>>> I guess the only concern I have with this approach is making sure it >>>> doesn't get in the way of developers - i.e. the uses should be >>>> calculated by the tooling vs expecting the developers to manage this >>>> manually. Uses is a pretty nasty equation to calculate at runtime and >>>> in an IDE environment where devs are cutting/refactoring code I guess >>>> I'm just wary that it has the possibility to spin out of control and >>>> lock up the IDE. Also should be careful at implementation time to >>>> allow the calculation to be done in such a way as to allow caching so >>>> it doesn't grind the IDE to a halt. >>>> >>>> >>> >>> I worry about this during framework run time too! :-) >>> >>> That's why we need to devise a decent algorithm that doesn't do this and >>> we >>> can share among our subprojects that require resolving. >>> >> >> Yep that would certainly be very useful! One of the comments made >> during the sigil contribution was regarding building a resolver API >> that could be reused and implemented in different ways, either for >> research purposes or to allow for different behaviours - fast, logical >> error messages, extended semantics, etc. Maybe we could look at some >> combination of code from Felix, OBR and Sigil to form the basis of an >> API? >> >> The key parts of the sigil resolver (I think) are: >> >> * support for progress notifications (allows for UI analysis of >> resolutions) >> * pluggable repositories (i.e. sources of bundles - filesystem, obr, etc) >> * support for hierarchical repositories (allows developers to chose >> where they would "prefer" to resolve resources from) >> > > While all of this sounds good, I was more alluding the algorithm > itself...the API is the easy part if we have an algorithm that is wicked > fast. :-)
Sure, I agree it's definitely possible to build an algorithm in isolation which is harder than the API. I just wonder whether there would be more impetus to try solving this if there were a pluggable API - kinda chicken and egg thing. I suspect there's a few people out there working on this problem but they don't necessarily want to donate the code to apache? If there were an API they could plug into then they could develop the code prove it worked and potentially contribute it later if they so wished? Might even spur some healthy competition in this area... Also I think wicked fast depends on your scope - for a runtime the problem is generally wiring together an order of around hundred or so bundles? For a development environment this potentially has visibility of a /lot/ more - i.e. in worst case all bundles ever developed. So this could be thousands, tens of thousands (or dare I say it millions) of bundles, solving uses in this area sounds (on first pass) pretty scary... Obviously one step at a time and nothing stopping people improving the algorithm now as you say, but allowing different research teams the ability to try different algorithms in the scope of a single resolver API sounds pretty neat to me ;) Regards, Dave > > -> richard > >> Regards, >> >> Dave >> >> >>> >>> -> richard >>> >>> >>>>>>>> >>>>>>>> * What to do about fragments? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> I don't think the fragment issue should be handled, since that is a >>>>>>> bogus >>>>>>> use case for fragments from my point of view. Fragments are intended >>>>>>> to >>>>>>> be >>>>>>> optional extensions to the host, but in this case the host is fibbing >>>>>>> about >>>>>>> its contents because it expects to have a fragment attached to it. In >>>>>>> reality, the fragment should have the exports, not the host. >>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>>> Tend to agree it is a bogus scenario - if only it wasn't happening in >>>>>> one of the most used OSGi libraries available :( I guess Eclipse >>>>>> probably have a good reason for doing this - not sure what but I'll >>>>>> give them the benefit of the doubt. >>>>>> >>>>>> >>>>>> >>>>> >>>>> Regardless, it doesn't seem like a good idea to create whole new >>>>> mechanisms >>>>> to support improper use cases. >>>>> >>>>> >>>> >>>> Agree in principle and I certainly want sigil to encourage best >>>> practice OSGi development. But in real world projects the edges are >>>> very rarely clean cut - so we need to provide migration paths at >>>> least. I'll push this out for the time being as I have a work around >>>> for fragments of this type - it's a bit messy but involves no new >>>> options on require bundle at least. >>>> >>>> Regards, >>>> >>>> Dave >>>> >>>> >>>> >>>>> >>>>> -> richard >>>>> >>>>> >>>>> >>>>>> >>>>>> I think I've figured out a way to work around it for the time being - >>>>>> which takes the pressure off from a sigil release point of view. I'll >>>>>> add the fragment to the ordinary classpath vs the OSGi filtered one, >>>>>> so I can at least compile against it without dragging in an external >>>>>> dependency at runtime. The danger with this approach is that unwary >>>>>> developers may link against a non exported package by mistake. Just >>>>>> wonder if there is a way to make this work without complicating the >>>>>> development model (or the sigil code) too much... >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>> >>>>>>> -> richard >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>>> >>>>>>>> * Is anyone still there (i.e. has this email lost you all?)? >>>>>>>> >>>>>>>> Regards, >>>>>>>> >>>>>>>> Dave >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>> >>>>>> >
