REPLY Who wants to share models (SD6890)

[SDMAIL Dan Goldner]

Posted by  Dan Goldner <dan at ventanasystems.com>

SDMAIL Tom Fiddaman wrote:
 > Right. One could certainly use a wiki for collaborative model building
 > as well (e.g., to keep a running discussion, documentation, and file
 > links), but I'm sure better tools could be found. Probably the
 > combination of a code management system and a forum would be better (as
 > most sourceforge projects have). I'll try to get a colleague to share
 > some experience using subversion (SVN) with Vensim text .mdl format
 > models. That lets users keep models coordinated and review past changes
 > (including who made them).

Tom mentioned Subversion, a version control system (subversion.org, or 
svnbook.red-bean.com for an introduction). This is more on the topic of 
how to collaborate on creating models than on sharing & cataloguing 
existing models.

Subversion keeps a history of changes to a model and allows multiple 
people to edit it, alerting them when conflicts have occured. My 
experiments with it have been very successful, though not without 
headaches.

The main benefit has been that multiple people can work on a model in 
parallel, and no previous revisions are ever lost. That is, Tom may make 
excellent changes in revision 326 that I carelessly destroy in revision 
327, but we can always revert to or copy & paste from rev. 326 to fix 
the error.

The headaches come from the fact that the system is designed to monitor 
changes to lines of programming code. This means if I do something I 
don't think of as "changing the model" such as nudge a sketch element to 
the left, or close the model with a different variable in the workbench, 
or put carriage returns in equation right-hand-sides for readability, 
subversion considers those to be changes. With practice though these 
become easy to avoid or manage when they occur.

Subversion does not do anything to help coordinate who is doing what. 
For that conversation you need either a wiki (see Tom's post) or an 
issue tracker (e.g. Trac - trac.edgewall.org) or an e-mail list like 
this one or regular meetings or something.

Karl Fogel has written excellent guide to managing collaboration among a 
disperse group at producingoss.com. It's focused on open source but the 
techniques are useful for any group.

Notes:
 -You need a server to use Subversion, but if you don't have one, an 
excellent hosted service for Subversion and Trac is available for 
$7/month from hosted-projects.com.

 -Lots of Windows users like to use tortoisesvn as an interface to 
subversion: tortoisesvn.tigris.org. Like subversion and trac, 
tortoisesvn is free.

Posted by  Dan Goldner <dan at ventanasystems.com>
posting date  Wed, 09 Apr 2008 08:55:41 -0700