1. A method of operating a computer in a distributed computer system, the method comprising the steps of: storing in a memory a plurality of classes, each class including data and at least one method, each method including a plurality of bytecodes, a subset of said bytecodes including symbolic references to methods accessible by said computer; flagging, for each said class, said class' data when said class' data is modifiable by one of said class' methods; substituting, for each said symbolic reference to a specified method stored in said memory, said specified method's memory location; flagging, for each said method of each said class, said method when one of said method's bytecodes includes a symbolic reference to a method not stored in said memory; and providing an executable module including each said class, wherein each unflagged method and each unflagged data is to be stored in a read-only storage medium when executing said executable module, and each said flagged method and each said flagged data is to be stored in a read and write-enabled storage medium when executing said executable module.