[Nodedb-interop] Database shema of Nodewatcher

[Mitar]

Hi!

> Can you explain "tree structure" a bit please? 

Sure.

There are in fact two trees. One is a tree of structures of
modules/addons/plugins announcing/adding/registering some (sub)schema in
the tree. For example, you have a router, which has one or more
interfaces, some of them are WiFi interfaces, which can have one or more
network configurations (for each SSID or something). So you have a tree
of features of this node.

This could be seen simply as a node table, having multiple other tables
(like basic features: interfaces and so on) using it as a foreign key,
then another tables (like subfeatures) using them and so on. But it is
more naturally explained with a tree.

Then there is a tree of inheritance. The idea is, that you have a basic
schema (for each part of the above mentioned tree) defined, which can be
inherited, new fields added, some hidden (and automatically filled in)
and so on. You should see this as an object-oriented classes and
inheritance.

So maybe forgot about databases, but see this as a tree of classes,
where classes could have their own inheritance, so you can replace one
class in a tree with one inheriting from it.

For such tree to be useful, you have to have some predefined tree
structure, so that you know where you can find classes you want, and
also to have those basic classes predefined, so that you can extend them
with new features.

So there are two dimensions in which you can extend the schema by
plugins/addons.

Some documentation on this tree representation of ours can be seen here:

http://dev.wlan-si.net/wiki/Nodewatcher/Registry
http://dev.wlan-si.net/wiki/Nodewatcher/Registry/NodeConfiguration


Mitar