Abstract: A method for hot swapping software libraries with dynamic version changes is provided. A sub-type relationship is defined between objects of an existing software library and an updated software library on a computer system, and optionally, subtype relationships are defined between objects of the updated software library and the existing software library to provide backward compatibility. A version adapter is defined for adapting objects for use by the updated software library, and stored in a table of version adapters. The updated software library replaces the existing software library. Existing client threads can continue to pass objects to the updated software library without experiencing a loss of service. Objects incompatible with the updated software library or the existing software library are identified at run-time, and a query is performed into the table of version adapters.