Web applications usually have a database. The code and the database work hand in hand together. Therefore Frameworks like Ruby on Rails and Django create migration files

Sure there are also servers written in Self or Smalltalk or other image-based systems that face the same problem: Code is not written on the server but in a separate image of the programmer.

How do these systems deal with a changing schema, changing classes/prototypes. Which way do the migrations go?

Example: What is the process of a new attribute going from programmer's idea to the server code and all objects?

I found the Gemstone/S manual chapter 8 but it does not really talk about the process of shipping code to the server.