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JMRI: Technology Road Map

This page is the road map for JMRI's future development, including changes to our use of Java technologies. It is maintained and updated through continuing discussion on the jmri-developers mailing list.

There's also a page containing the history, particularly the saga of how we moved forward to Java 1.6 and Java 8 across a series of platform-related changes.

JMRI Releases

This section describes the (notional) plans for JMRI releases in the future.
Release Description Date JRE JDK
3.11.* Development series 1.6 8
4.0 Production version, culmination of 3.11.* series July 2015 (done) 8 8
4.1.* Development series 8 8
4.2 Production version, culmination of 4.1.* series December 2015 (done) 8 8
4.3.* Development series 8 8
4.4 Production version, culmination of 4.3.* series Early Summer 2016 8 8
4.5.* Development series 8 8
4.6 Production version, culmination of 4.5.* series Late Fall 2016 8 8
4.7.* Development series 8 8
4.8 Production version, culmination of 4.7.* series Early Summer 2017 8 8
4.9.* Development series 8 8
4.10 Production version, culmination of 4.9.* series December 2017 8 8
4.12 Production version, culmination of 4.11.* series July 2018 8 8
4.14 Production version, culmination of 4.13.* series December 2018 8 8
4.16 Production version, culmination of 4.15.* series July 2019 8 8
4.18 Production version, culmination of Fall 2019 series December 2019 8 8
?? Production version, culmination of Spring 2020 series July 2020 ?? ??

JMRI in the Near Future

The 4.1.* series of test releases in Fall 2015 started the requirement for Java 8, also known as Java 8. This has continued through the following release series. The December 2018 release, notionally JMRI 4.14 will remain with Java 8, but may involve other library updates. This includes doing development, test and production release builds using Java 1.8.0_181. (We also test on Jenkins with Java 1.8_0_151 to ensure Windows XP compatibility)

The current long-term-support Java release is Java 11 from Fall of 2018. Oracle has aligned their Java and the OpenJDK from that point. Because some people will need to have that on their computers for other purposes, we ensure JMRI can build and run on Oracle Java 8 through 11 and OpenJDK version 11 by using Jenkins to

You can follow the current status of these on the CI Status page.

At some point, the Java version required by JMRI has to move forward. For example, Oracle has announced that they'll stop providing standalone JRE installers by the end of 2020, by which time JMRI distributions will have to contain the Java runtime components or it won't be possible to run JMRI on newly-bought PCs (will continue to provide independent JREs). That in turn might require tools like jlink from Java 9 or later.

While we don't know yet when JMRI will have to move past Java 8, we do know that the earliest Java 9 or later will be required for users is Fall 2020. Allowing for migration and development time, and depending on development plans, JMRI's December 2020 release might require Java 11 (in which case it would be called JMRI 5.1) or stay with requiring Java 8 or later (in which case it would be called JMRI 4.20). Releases before Fall 202 are intended to stay fully compatible Java 8.

It's possible that, as an intermediate step, JMRI development will move to a later Java SDK version without requiring that JMRI users move to a later Java JRE version. For example, it's remotely possible that JMRI will require a Java 11 SDK to compile and build distributions, which would still be able to work on Java 8. We prefer to do that to keep older hardware working, but it's not always possible. (Note: Here, we're talking about using the Java 11 SDK, not about using Java 11 language features. Java 9 through 11 SDKs require setting their source version and runtime version to the same value; you can't compile i.e. Java 11 source code for a Java 8 runtime)

There are also smaller migration issues. These don't directly affect JMRI users in the way that Java version changes do, but they may effect external users of the JMRI libraries.

Java Release and Operating System Support

More information on Java releases and the operating systems that support them is on a separate page.

Migration Notes

This is a section of notes for various code migrations that are in progress or contemplated.