Selecting a common sense approach, based on detailed analysis of target and existing architectures, yields the best results. Several redevelopment options can be applied as a way to retool legacy architectures. Regardless of the approach, systems should be phased in over time, while deactivating legacy components along the way. One approach is to create a system to support the cross section of the business being reengineered. In the order processing example, this means mapping all business rules extracted from multiple standalone systems to a target design model.
Rule extraction is accomplished using a combination of slicing and cross-system extraction tools.
Another approach, applying similar techniques, performs multi-system integration on all relevant systems. This approach retools the existing architecture on a broad scale. The focus is on mapping legacy to target design models, rule reuse, redundant rule consolidation, legacy deactivation, and transition management. Both approaches require phased decomposition of existing systems into reusable business logic, data access, and communication segments. Data store consolidation and redesign is performed concurrently.