reasons to add readability edges when creating layer

[Michał Zegan]

Seems to me like a good argument for layers as sets of interdependent
modules, as a module using another module prevents unloading the other
module for real, as references still exist to it from the first module.
Although I am not a module expert and trying to learn a bit about those
things.
As for jboss allowing dynamic dependency modification, I just haven't
found that ability, but I have looked mainly at Module, ModuleLoader and
such classes.

W dniu 03.01.2018 o 15:04, David Lloyd pisze:
> On Sun, Dec 31, 2017 at 10:06 AM, Michał Zegan
> <webczat_200 at poczta.onet.pl> wrote:
>> Is that planned to be added? Or even needed? I wanted to compare jpms
>> api to jboss-modules and seems to me that jboss-modules does not have
>> the dependency modification capability at all at the first glance.
> 
> JBoss Modules does allow modification of dependencies and even
> unloading of modules, however it must be done carefully (of course)
> with an understanding of how class loading works.
> 
> This is not something that you will commonly want or need to do,
> because Java class linkage is a one-time operation.  This means that
> if your module X depends on module A and a class from X links to a
> class form A, and you change the dependency from module A to module B,
> X will still have a connection to module A via the already-linked
> class.  This is possibly the simplest example of where problems may
> begin.
> 
> That said, the JBoss OSGi project uses this feature to implement its
> relinking capabilities.  It mitigates the possible problems by way of
> its service container which helps to minimize the risk of problematic
> activity.
>