Modules with platform specific parts

[Alan Bateman]

On 15/09/2021 09:45, Johan Vos wrote:
> Hi,
>
> There have been discussions in the past about how to deal with
> platform-specific parts (java code, native code, resources) in modules.
> There is no standard for this, and afaik no recommendation. In the OpenJFX
> project, we upload jars with module info to maven central, and we have
> plugins for maven and gradle to deal with them at compiletime and at
> runtime.
>
Project Panama and the foreign linker API may be another motivation to 
re-visit this topic. One general concern is adding more complexity to 
the JAR format. I could imagine platform specific sections adding 
another dimension of complexity to MR JARs, modular JARs, modular MR 
JARs, ...  Also every bag we nail on could have implications for compile 
time, packaging time, jlink, and run-time.

The position we took on this in JDK 9 is that modules can be platform 
specific. There is a JDK-specific class file attribute named 
"ModuleTarget" for the OS and/or architecture.  The jmod tool has an 
option to specify the OS/arch when creating a JMOD. Post resolution 
checks will catch issues where someone accidentally deploys a module for 
the different OS/architecture. I have not looked at the JavaFX modules 
recently but at some point I think they were packaged as JMOD files and 
it might be that the platform was specified at that time. If you've 
since moved to modular JARs then I could imagine this getting lost.

-Alan