Hi everyone. I'm working on UEL engine migration (OFBIZ-12991 [1]).
Why ?
It starts from the idea of creating a Prometheus plugin, allowing to
expose data to grafana. There is a lib that exists in java. [2]
This lib comes with an integrated httpserver but it would be much
cleaner to use the tomcat server already present in OFBiz, but the java
lib uses jakarta, making it imcompatible with Tomcat 9 (the current
version in OFBiz) that still uses javax.
For OFBiz to be able to switch to Tomcat 10, we need to switch to javax
to jakarta.
And OFBiz uses a library for UEL that has had no update in the last 10
years, and still uses javax [3]
The thing is that we still need (IMO) to have custom overrides of
libraries that implements UEL. All UEL implementation cases i saw still
won't allow for auto-vivify. [4] [4bis]
This would prevent some uses of null map keys in XML scripting from what
i understand. I don't know if it's a big change, or regression.
Now my problem is that i don't know how to procede. The work of
migrating the library has been done but not merged (yet ?) [5]
I can't find an other library that would suit the existing code without
having to re-write a lot of code.
I think i understand some of it currently works, but i can't figure out
how to keep going after that.
One possibility would be to see if we can use jakarta vanilla EL [6].
An other possibility could be to have both javax and jakarta (for some
time) to give us some time for migration.
Any thoughts ?
Gaetan
[1] https://issues.apache.org/jira/projects/OFBIZ/issues/OFBIZ-12991
[2] https://github.com/prometheus/client_java
[3] https://mvnrepository.com/artifact/de.odysseus.juel/juel-impl
[4]
https://github.com/apache/ofbiz-framework/blob/6039526c744e1a75e5c40b553de964041f386531/framework/base/src/main/java/org/apache/ofbiz/base/util/string/UelUtil.java#L461
[4bis] https://en.wikipedia.org/wiki/Autovivification
[5] https://github.com/beckchr/juel/pull/104
[6]https://jakarta.ee/specifications/expression-language/4.0/jakarta-expression-language-spec-4.0
PS: Thanks Gil for helping me get some clarity in this VAST subject
