DIagrams and PlantUML

Okay Spec hive-mind, I have a quandary.  The Web Payments (IG, WG) and the
Credentials Community Group, and the Verifiable Claims Task Force, and
possibly others, are using PlantUML to draw clever little flow diagrams
etc.  PlantUML is a simple textual UML grammar.  The plantuml engine is
open source, and relies upon GraphViz (also open source) to generate
various formats, including SVG.

All that's great.  But the people using this don't *want* to have to
generate an SVG version of their diagrams.  They just want to include the
PlantUML source and have magic occur.  That is *possible* in ReSpec using
@data-transform and a function, but the way it is possible is by relying
upon a plantuml proxy server at www.plantuml.com.  I am personally wary of
this because 1) we have no control over it, and 2) it just feels rude to
start hitting their server all the time.

So, here are the options as I see them:

   1. Put an instance of a plantuml server up at the W3C somewhere and hit
   that for dynamic diagram generation.
   2. Use the plantuml.com server and just (fingers crossed) hope it keeps
   working.
   3. Add something into the github flow so that when certain filetypes are
   pushed (*.pml) updated versions of their static versions are automatically
   generated and put into the repo (*.svg).  That generation could happen
   using plantuml.com or a w3c server or something else.
   4. Tell people to generate static versions by hand and commit them into
   the repo.

What do others think?  Is there a more sensible way to approach this
problem?

P.S.  If you want to see an example of what is being done, check out the
use case document we are working on at [1] or the web payments flows work
as described in its wiki at [2].  Or, of course, just look at the plantuml
site at [3]

[1]
http://www.opencreds.org/specs/source/use-cases/#how-a-verifiable-claim-might-be-used
[2] https://github.com/w3c/webpayments/wiki/Flows
[3] http://www.plantuml.com


-- 
Shane McCarron
Managing Director, Applied Testing and Technology, Inc.