[Extgraph-developer] Architecture talk (aka Proxy)

[Marco W. <in...@ca...>]

Ok guys,

I've had a change of mind. The previously mentioned Proxy component is 
not really a proxy but more of a Bridge. Thinking this through more and 
more doesn't reduce the work at hand. I've more or less re-factored the 
svg into a egSvgBridge, egSvgNodes and implemented a very(!) rough 
TExtGraphBridge. At this moment it is nothing more than extracting the 
svg stuff and pushing it into a seperate unit. The two-way communication 
between the xml dom tree and the ExtGraph is not complete. Since I don't 
have the xml components I won't get it to work as easily as I would like to.

So, to divide the workload I would like Parvel to have a look and see if 
he can repair the damage I've done to it. My future thoughts on the 
Bridge technology goes beyond the svg implementation. It would even 
allow multiple ExtGraphs with a single Bridge. To really make this work, 
more internals on node and link manipulation need to be extracted from 
the ExtGraph class. More logic needs to go into the ExtGraphBridge 
class. Not really difficult, yet it requires a lot of work and re-factoring.

I'm thinking to far beyond to pull this off in a single increment. The 
idea is to go towards the following architecture in several code increments:

ExtGraph -> CustomBridge
                 |
           /-----------\
      ExtBridge     SvgBridge


              GraphObject
                   |
                   ^
              /---------\
          GraphNode  GraphLink
             |               \
             ^                \
        /---------\            \--------\
RectangleNode  SvgNode          \        \
                           BezierLink CurvedLink


ExtGraph is to be responsible for the drawing and gui of the graph 
itself. It will still control all nodes and links, yet allows the 
ExtBridge to intercept all communication on the collection of nodes and 
links it displays. Instead of having eventhandlers on the ExtGraph 
itself these will be moved towards (or extended on) the ExtBridge. The 
other way around the Bridge will contain methods to insert nodes and 
links into the ExtGraph. Different bridge classes, like SvgBridge, will 
service other methods which allow a different language (svg) to be used 
to manipulate the nodes and links on the ExtGraph.

I do hope this makes sence to you all. I can barely keep up my thought 
train, and certainly miss the time to implement all of this. Yet my gut 
feeling says this is the way to proceed as far as the architecture is 
involved. If you have the energy and insight please come back to me on 
this or help me convert at least a SvgBridge to make this first 
increment work. Personally I will attempt to continue the work on a 
ExtBridge layer and a custom Bridge for CaseTalk and see what is needed 
for the communication between components to make it all work transparent...

Hope you are all well and coding. ;)

Regards,
Marco.