Legacy systems is always a case in the real world, and they come with exciting challenges while we try to incorporate the latest industry improvements into them. In DDD, this problem is more interesting to address as there are many handy patterns available that help limit the impact of the legacy on the other parts of the system, manage complexity, and save designers from having to reduce explicitness (against DDD philosophy) of their new code to integrate into legacy modules or components.

We will touch upon bubble context, autonomous bubble context, and expose legacy systems as services in this section.