Schema plugin / Add schema bean to make it more plugable

[fxprunayre]

See proposal for details https://github.com/geonetwork/core-geonetwork/wiki/Proposal:-Schema-plugin-improvement

[jesseeichar]

Looks good +1.

[Delawen]

What about the future improvement on dynamic loading of schemas?

I think this is important, specially if we want to simplify the process and allow users to add and update schemas using a UI. With this change we will not only have to restart the server, but also modify the original war/folder on tomcat when we add or update a schema.

I am not saying we shouldn't merge this, I think it is great improvement and very helpful.I am just a bit worried on this point. Loading java classes outside the default classpath is a bit complicated. I tried to do that on a previous project a few years ago and it was feasible but a bit nightmare... not sure if I just didn't know how to do it properly.

[fxprunayre]

What about the future improvement on dynamic loading of schemas?

I may be wrong, but I don't see many users adding dynamically new schemas using the web interface. Most of the time, we build custom GeoNetwork with some custom schemas and users are installing those applications (like Anzmest, GéoSource, Geonovum, CDI, Sextant, ...). Having a good documentation explaining how to add a schema and even if it requires a restart of the application sounds enough for me.

With this change we will not only have to restart the server, but also modify the original war/folder on tomcat when we add or update a schema.

Only if the plugin add a custom bean which is optional and should not happen for all existing ISO19139 profiles.

[Delawen]

You convinced me 👍