Module container format

[Alan Bateman]

On 02/07/2015 20:01, offbynull-jigsaw at offbynull.com wrote:
> The JEP says that the module container format is 
> "implementation-specific" and "subject to change without notice". My 
> concern is that this is going to end up screwing over tool 
> maintainers, such as myself. I maintain an opensource tool that scans 
> through core Java classes for instrumentation purposes. It's supposed 
> to be able to target code written for Java 1.4 and above. I can force 
> my users to use Java9 to run the tool, which means that that the tool 
> will be able to read core Java9 classes via the jrt:/ URL solution. 
> But what happens when Java10 comes out? Will my users be able to scan 
> core classes in Java9 if the tool is running on Java10?
>
> So far, it looks like nothing in the JEP covers this. As far as I can 
> tell, the jrt:/ URL solution only reads core classes/resources from 
> the version of Java that the tool is running on.
Search for "jrt-fs.jar" in the JEP.  As things stand in JDK 9  then you 
run the tool on JDK 8 to access the contents of a JDK 9 run-time image 
or run the tool on JDK 9 to access itself.

We're not there yet but eventually it should be possible to run a tool 
on JDK 9 to access another JDK 9 run-time image (maybe it has a 
different set of modules) or run on JDK 9 to access a JDK 10 run-time image.

-Alan.