RFC: Graphical Database Editor

[Andrew Johnson <anj@aps.anl.gov>]

This message is a Request for Comments and meant to start some discussion
on how we create and edit EPICS databases, an area in which I believe we
are lacking a major tool.  This proposal will not be appropriate for all
sites, but I believe that I have found a good starting point for
developing a suitable hierarchical graphical database editor.  I'm also
looking for anyone interested in collaborating with the necessary
development work.

TkGate (see http://www.cs.cmu.edu/~hansen/tkgate/ for screen shots &
source download) is a free [GPL] schematic capture program (and a circuit
simulator although that's of no use to us) which is written in a
combination of C and tcl/tk.  It supports hierarchical editing and
printing to PostScript, and internally seems nicely modular.  I think it
would be worth using this as the basis for developing a proper graphical
database editor.

NB: TkGate already includes support for Japanese as well as English; if
KEK or another Asian lab were to get involved we could aim to maintain
this in the db editor, and maybe add other languages too.

I can foresee questions/objections from some sites - tkGate doesn't run
under Windows (although most Unix flavours are supported) because it uses
X for drawing whereas AIUI Tk uses the windows GDI on that platform.  I
don't know how much work it would take to make it portable, but it will
probably help that we'll be stripping out a lot of graphics stuff from the
current tkGate code.  I have no interest in working on a Windows version
myself though.

Here is an initial list of jobs that will need doing; I've not gone into
the source in too much detail yet so this is only very preliminary:
  * Document what we're aiming to produce (requirements)
  * Analyse the existing code more closely to understand it
  * Remove the simulator and support for most schematic objects
  * Replace the verilog load/save format with dbStaticLib
  * Work out how to retain graphical layout data in dbStaticLib
  * Write a generic "record" schematic object
  * Modify the hierarchy object (module) to add macros
  * Overhaul the object Properties dialog & support
  * Create a crude auto-layout engine for existing .db files?
  * Modify wiring routines to handle INP/OUT links and fields
  * GUI changes

All comments welcome, both positive and negative.  If someone already has
a better proposal or source code to start from I think we should start
discussing it - IMHO we *need* a graphical editor that properly
understands databases, or EPICS will not survive and grow in the longer
term.

- Andrew
-- 
Sharks kill 10 people each year.  People kill 60,000,000 sharks each year.