[logback-dev] Logback source code organization and extensions

[Les Hazlewood]

Hi Ceki (et. al),

I'm trying to wrap my head around making it easy to add and support
contributions/extensions to logback in a clean/modular way.  For
example, I'd like to see a JSON formatter and a Loggly appender added
to Logback.

However, these additions probably don't make sense to be added to
logback core/classic as they would bloat the library for those not
using these features.  As such, it makes sense (to me at least) to
have a more modular source code organization where different
features/extensions are represented as a dedicated Maven module.  This
way, people can easily (and deterministically) use a respective
dependency depending on the feature they wish to enable.  Clean and
easy.

Now, with regards to a JSON formatter and a Loggly appender (which
would likely use the JSON formatter), I'd envision something like this
in the Logback source tree:

logback/
  logback-access/
  logback-classic/
  logback-core/
  ...
  logback-extensions/

Where 'logback-extensions' is a new Maven module.  It would just be a
wrapper module containing children.  Below it, you might see the
following:

logback-extensions/
  json/
      common/
      groovy/
      jackson/
  loggly/
  foo/
  bar/
  ...

In the above example, the logback-json module: 1) provides a 'common'
sub module where JSON-specific needs are defined, and 2) has other
sub-modules depending on _how_ you want JSON to be formatted.

You can depend on the logback-json-jackson dependency if you want to
use Jackson, or you can depend on logback-json-groovy if you want to
use the built-in JSON support in a Groovy 1.8+ environment.
The 'loggly' extension could depend on logback-json-common.

The idea is that you can depend on a dependency that is copacetic with
your intended runtime environment.  I think this makes a lot of sense
- we use it in Apache Shiro
(http://svn.apache.org/repos/asf/shiro/trunk/support/) and it works
very well for us.

Before I go off and create my own 'logback-extensions' project on
GitHub, I'd rather contribute this back to Logback proper as a pull
request if this is something you are willing to implement.

Thoughts?

Cheers,

-- 
Les Hazlewood
CTO, Katasoft | http://www.katasoft.com | 888.391.5282
PMC Chair, Apache Shiro | http://shiro.apache.org
twitter: @lhazlewood | http://twitter.com/lhazlewood
katasoft blog: http://www.katasoft.com/blogs/lhazlewood
personal blog: http://leshazlewood.com