Toward Class Evolution in Persistent Java?

The appeal of persistent class-oriented programming languages is great. Allowing class definitions to be persistent, in addition to instance data, greatly increases the ease of achieving and maintaining consistency among type definitions and their instances. Persistent class definitions become a serious impediment if they cannot evolve, however, as software systems are constantly evolving. In previous work we demonstrated Jspin, an orthogonal persistence extension for Java that does not require a modified Java Virtual Machine. In this paper we discuss our progress towards extending Jspin to allow persistent class definitions and evolution of persistent classes. We believe that we have succeeded in doing this in a way that still allows operation in an applet environment.