Software Architect's Handbook

Sharing functionality between systems

When a newer software application is integrated with a legacy one, some of the functionality may be duplicated across the two systems. Software architects should be aware of any overlaps because decisions will need to be made as to which system will be responsible for functionality that is shared. Any differences in shared business logic between the two systems should be identified, as those differences may play a factor in such a decision.

Any logic that is redundant between the two systems is a candidate to be exposed and shared so that it is no longer duplicated. This will ensure consistency of the logic. Quality and maintainability will be increased as the logic will only need to be maintained and ...