Project Jigsaw: Phase Two

Project Jigsaw has, for the last several years, been in an exploratory phase in which we’ve designed and prototyped one particular approach to addressing a draft set of requirements.

It’s now time to switch gears and focus on creating a production-quality design and implementation suitable for JDK 9 and thence Java SE 9, as previously proposed.

To begin this phase I’ve drafted a new document to collect goals and requirements. It reflects a new emphasis on security, as motivated by recent experience, it takes into account lessons learned from the prototype, and it’s written at a broader and more abstract level than the previous document so as not to over-constrain the solution space. This document will be one of the starting points of the upcoming Java Platform Module System JSR.

Jigsaw as a whole will bring enormous changes to the JDK; it would be unwise to wait until it’s completely finished before merging any of it. Our intent, therefore, is to proceed in large steps, each of which will have a corresponding JEP. The first three JEPs will propose a specific modular structure for the JDK, reorganize the JDK source code (but not binaries) along those lines, and then later modularize the binary images.

A fourth JEP will introduce the module system itself, which will be aligned with the module-system JSR. It may seem odd that the module system JEP comes last, but the earlier JEPs need make only minimal assumptions about its capabilities, hence work on them can proceed in parallel with work on the module-system JEP and JSR.

Comments, questions, and suggestions are welcome on the jigsaw-dev mailing list. (If you haven’t already subscribed to that list then please do so first, otherwise your message will be discarded as spam.)