Add Jython and Groovy ScriptEngineFactories

[5iver]

... and add support for Jython and Groovy scripted Actions and Conditions in Paper UI.

Fixes #521

Signed-off-by: Scott Rushworth openhab@5iver.com (github: openhab-5iver)

[kaikreuzer]

I have one general concern with this change:
The reason that only Javascript is listed is that it is always present.
For Groovy and Jython, additional libraries need to be in place. For installations, where those are not installed, the UI should also not display these options.
I'd thus think that the registration of the factories + config description should be constructed dynamically, wdyt?

[kaikreuzer]

Please use the license header from https://github.com/openhab/openhab-core/blob/master/licenses/epl-2.0/header.txt

[5iver]

I'm not sure if I should use this...

Copyright (c) 2010-${year} Contributors to the openHAB project

Or...

Copyright (c) 2010-2019 Contributors to the openHAB project

[kaikreuzer]

Clearly the version with the years, not the placeholders!

[5iver]

I thought so... but clearly not so clear to me! Thank you! 😄

[kaikreuzer]

Please add some Javadoc

[kaikreuzer]

Please add some Javadoc

[5iver]

I'd thus think that the registration of the factories + config description should be constructed dynamically, wdyt?

Absolutely, but I did not see how to dynamically construct it. Could you please point me in the right direction on how to do that?

[kaikreuzer]

Well, the first thing is to figure out how to determine whether support of these languages is there or not.
Then you could write some code that registers a marker service and have a mandatory dependency of the factory to that service.

For the config options, this should be removed from the static json file and be implemented as an ConfigOptionProvider instead.

[5iver]

Well, the first thing is to figure out how to determine whether support of these languages is there or not.

1. We could include the libraries by default, but that would take up about 42Mb to the distribution, so that is likely not an option.

2. We could add Jython and Groovy bundles that install the necessary libraries in the classpath, and possibly in the future include some helper libraries and scripts. With this option, we could check for the existence of the bundle(s) in the ConfigOptionProvider.

3. In the ConfigOptionProvider, we could check to see if the libraries are in the classpath.

Option 3 looks best to me, in case the libraries are manually installed. Adding some bundles for JSR223 libraries is on my list though! What type of bundles would these be?

[openhab-bot]

This pull request has been mentioned on openHAB Community. There might be relevant details there:

https://community.openhab.org/t/configuration-of-openhab/64682/203

[kaikreuzer]

I think 2+3 should be combined.

Adding some bundles for JSR223 libraries is on my list though! What type of bundles would these be?

What do you mean by type? Wrt the id, it could be org.openhab.core.automation.module.script.jython and org.openhab.core.automation.module.script.groovy.

[5iver]

I think 2+3 should be combined.

If 3 is implemented, I don't see any need for 2. The bundle could be installed but misconfigured. Checking the classpath will tell us for certain if the libraries are available for use.

But I'm rethinking this. Instead of checking the classpath, I can get a list of ScriptEngines from the ScriptEngineManager. I also don't think these factories will be needed, since they are really just providing the MimeType for the ScriptEngine, which is used in the ScriptTypes.json. But I'm thinking the name might be able to be used (need to test), which can also be provided by the SEM. This will also allow for something like a Kotlin library to be added into the the classpath, a ScriptEngine would be created by the GenericScriptEngineFactory, and then it would show up as an option in Paper UI.

What do you mean by type?

I was meaning binding, io, etc., but don't know the right terminology for it. I'm confused by org.openhab.core.automation.module.script.jython, as I was thinking these would be in openhab2-addons.

I have a number of questions, so I opened a separate issue for Jython... https://github.com/openhab/openhab2-addons/issues/4801, and I'll open another for Groovy.

[5iver]

Replaced with #635.