Global Reset

Thanks to Ted Neward, I just read about this interesting new Java Specification Request: JSR 277

The specification of the Java Module System should define an infrastructure that addresses the above issues. Its components are likely to include:

1. A distribution format (i.e., a Java module) and its metadata as a unit of delivery for packaging collections of Java code and related resources. The metadata would contain information about a module, the resources within the module, and its dependencies upon other modules. The metadata would also include an export list to restrict resources from being exposed outside the module unintentionally. The metadata may allow subset of exposed resources to be used by other modules selectively.
2. A versioning scheme that defines how a module declares its own version as well its versioned dependencies upon other modules.
3. A repository for storing and retrieving modules on the machine with versioning and namespaces isolation support.
4. Runtime support in the application launcher and class loaders for the discovery, loading, and integrity checking of modules.
5. A set of support tools, including packaging tools as well as repository tools to support module installation and removal.

We also expect the Java Module System to expose the public J2SE APIs as a virtual module in order to prevent unwanted usage of the private APIs in the implementation.

Modules with metadata about their dependencies sounds like just what the doctor ordered. It’s crazy that Java has such a large and pro-active userbase, yet it is so slow in catching up to the fledgling .NET. Item #1 and #2 should’ve been implemented a long time ago, and Sun knows it. I agree with Ted as well when he says:

About the only thing I *wish* we could do that’s out-of-scope to the JSR is to fix the javac compiler to cease emitting .class files directly, but instead consider .class files to be the moral equivalent of C/C++-compiled .obj files, and automagically do that final step and turn it into a .jar file right out of the box. (Out of curiosity, is there anybody out there who doesn’t immediately jar up your .class files?)

I know I immediately jar mine up, except in the cases where I’m prototyping with a single .class. If Javac auto-jarred, that wouldn’t bother me in that case.