Imagine a C++ framework as a business layer, but with controlling logic as well. E.g. user rights, state of the webflow etc. With some plain C code to access DB2. The whole framework is host based. We are looking for a way to replace the existing framework gradually with a java framework. The main challenges are: the application is already huge, there are several application clients connected to the c++ framework at the same time (it's one web application with many instances), my knowledge of what is possible today with java on host is very limited (since all people I work with stick with C++)
Do some good ideas exist for gradually moving the old framework without breaking existing code? I guess as entry one would expect a web service or RMI server for transactions. But how to replace the business/controlling logic gradually is still a black box to me.