Consider Jackson 4.0.0 branch built with Java 11 and supporting the Java Module System

[guaporocco]

Jackson is a great library, but its frustrating that we can't use it with the Java Module System. Yes, jackson does have automatic module names, but you cannot build a minimal application image (jlink) or installer (jpackage) without explicit module-infos.

I tried forking jackson databind and its dependent projects, generating module-infos with jdeps, and then using javac --patch-module to repackage, but jlink still fails because it sees the Automatic Module Name field.

Although maintaining another branch may be require extra work, I think its worth considering to get the performance and size benefits of Java 11's defining feature. And since Java 11 is LTS, I expect the 4.0.0 branch would be created eventually.

[guaporocco]

I should add that modules could also help structure Jacksons code. jackson-databind depends on java.desktop, java.sql, and java.xml, for example, and since most developers don't make use of when using Jackson, databind could be split into modules databind.sql, databind.xml, etc.

[cowtowncoder]

Please do not file issues suggesting wide-ranging fundamental changes; instead bring them up on mailing lists. That's a good place to discuss these.

There are plans to use Moditect to make 2.10 and onwards (more) forwards-compatible, being built using JDK 8, but having basic module definitions, but still targeting Java 7 bytecode. Latter may become non-goal.

For 3.x this is the minimum baseline as well: baseline was moved to Java 8.
At this point I would like to make things work with module system, but have no personal interest in JDKs beyond 8, feature-wise yet. This may change depending on how long it will still take to get to 3.0 release, as well as adoption. At work, for example, I would not be able to use anythjing that relies on Java 11. Adoption has been slow, due to the way Oracle decide to force their ill-advised module upgrade, which essentially requires all-or-nothing approach.
Things will move along, of course, but I don't want to be on the bleeding edge working for things I have serious reservations about.

[guaporocco]

Using Moditect to generate module definitions would be very nice, hopefully databind is published in multiple modules (so that one does not have to rely on all each java.[xml, desktop, sql]).

I agree that the module system is somewhat of a pain and will have slower adoption. It's quite useful to build super-small docker images though (has saved us some money at least). And I'd expect that when Valhalla releases with value types in a year or two, there will be a big migration like with lambdas.

[cowtowncoder]

The issue of what to do with non-core JDK datatypes is interesting. Perhaps it'd be best to cleave them out and add a separate "jackson-datatype-jdk[11]"...

As to Moditect, I will either need to find time to dig into it, or get help -- some contributors have helped with prototype, but I don't think we have yet functional solution that I find good enough (there have been discussions on baseline, requirements and so on).