On 04/25/2017 09:15 AM, Brian Fox wrote:
On Tue, Apr 25, 2017 at 9:10 AM, David M. Lloyd <david.ll...@redhat.com <mailto:david.ll...@redhat.com>> wrote: I agree with everything except for this last point. I think that, given the amount of evangelism over the past 5 or so years, people will adopt JPMS whether or not it is a fit for their use case. Different shops will use different tooling in different ways to work around these problems; I expect that automatic modules will probably be mostly ignored except for "hello world" type cases in any event though. How would shops do this if everything they need from the ecosystem is itself unmodularized? Maybe app authors will do so and take the pain begrudgingly, but all the libraries that make Java such a powerful ecosystem probably won't because they'll be caught between downstream and upstream users.
I think that Maven- and Gradle-based tooling will appear to fill this need. The only correct solution (automatic modules or not) to modularizing arbitrary groups of artifacts will likely involve a separate assembly step which will inevitably include writing or rewriting module descriptors. I expect that the tooling will use the artifact dependency graph, module descriptors and/or other metadata present on the artifacts, and some manual configuration as input, and then produce as output a collection of corrected/re-written module JARs (and probably a complete wiring report that can be checked over by human eyes, probably with admonitions relating to potential or definite problems).
I really don't see any other way things could possibly work consistently for any application which uses external JARs. Automatic modules are just going to be a stumbling block to reaching this conclusion.
OSGi, by the way, avoids this situation somewhat more effectively than Jigsaw can, mainly because of three factors: resolving by package instead of by bundle name, performing the bulk of resolution work at run time, and by the simple fact that it is less invasive towards reflection, thus there is more "wiggle room".
This isn't to say that OSGi is an ideal solution of course, but I just wanted to point out why the OSGi ecosystem can generally get away with publishing artifacts containing descriptor information, while Jigsaw probably won't be able to (or at least, not as cleanly).
-- - DML
