Yesterday I posted TransmissionLab version 1.4, a fairly major reworking of the model class core. I was dissatisfied with the way that RepastJ models, by default, seemed to tightly couple the main model class to all of the other classes I’d written for data collection, transmission rules, and population construction. My goal with TransmissionLab is really a framework for building models to study cultural communication and transmission, not just writing one giant model and bolting new stuff on.
A paper by Railsbeck et al., in the September 2006 issue of Simulation, is right on the money in saying that the original Objective-C version of the Swarm toolkit is a strong “framework,” as opposed to the “library” style of successor toolkits like RepastJ and MASON. Swarm definitely forced a style of organization onto your simulation models, via the concept of nested “swarms” of agents, observers, etc. I suspect this is much like Ascape, but the latter doesn’t seem to be an active development project any longer (at least given the website – leave a comment if this incorrect). Whereas Repast provides a ton of infrastructure but simulation models themselves seem to be fairly unstructured, as I read various examples and models folks have posted online.