Khoros[1], AVS[2] and LinkWinds[3] all do the same sort of thing as OpenDX.
I think these sorts of "boxes and arrows" programming systems suffer from being monolithic environments with idiosyncratic interfaces and little or no support for external software engineering tools. What's worse for them is they generally compete for mindshare with scripting languages or scriptable environments (i.e. things like Mathematica) with larger communities.
I don't think they will ever gain wide acceptance until they allow the same level of reuse as systems based on structured text.
I think these sorts of "boxes and arrows" programming systems suffer from being monolithic environments with idiosyncratic interfaces and little or no support for external software engineering tools. What's worse for them is they generally compete for mindshare with scripting languages or scriptable environments (i.e. things like Mathematica) with larger communities.
I don't think they will ever gain wide acceptance until they allow the same level of reuse as systems based on structured text.
[1] http://www.arsc.edu/support/resources/khoros.html
[2] http://www.avs.com
[3] http://www.openchannelfoundation.org/projects/LinkWinds