Depending on the size and complexity of a legacy application, redevelopment on a lower cost platform can also make sense. However, it is not always a practical option. Large applications can sometimes take several years to rewrite and there may be limited in-house expertise of the legacy application, making it difficult to re-implement the business logic. A redevelopment project generally involves designing a completely new system that utilizes a modern Web services architecture to implement the business logic of the legacy mainframe application.

This approach enables the application to be optimized to the business processes of the organization and provides maximum control over the destiny of the application. In-house developers can make modifications to the programs or add new features when necessary. The flexibility and control of this approach is balanced against the high cost of software development projects and the ongoing expense of maintaining the software system in-house.

New applications redesigned to meet the current business needs

	High Risk for significant Cost and Time overruns
	Very costly compared to other options
	High risk of losing functionality in the initial implementation
	Complete retraining of both technical and end user personnel

When an application no longer meets the needs of the organization a rewrite option might be selected. Since a rewrite often involves new development environments and developers not familiar with either the applications themselves or how the company uses them, this option represents the most costly and highest risk option for completing a legacy transition project. Most organizations do not have adequate documentation describing the functionality of the application either from an end user or systems perspective.

Most organizations do not have adequate documentation describing the functionality of the application either from an end user or systems perspective. Often programmers who originally wrote the applications are no longer with the organization. The combination of these components makes it very difficult to fully understand the logic behind the applications. This requires a set of preliminary projects before the rewrite even starts.

One preliminary project involves documenting the existing functionality both from a technical and user perspective. This is essential to ensure that no critical functionality is lost in the rewrite. A second preliminary project involves the documented design of the new system. Since most of these projects are undertaken due to a lack of functionality in the existing environment, these changes can be extensive. It is a difficult and time consuming task to properly ensure that no functionality required to operate the business is lost and new functionality is well thought out so that it provides the value it was intended to provide. Virtually all of these projects result in significant cost and time overruns.

If predictability of cost and delivery time table is important and keeping the cost of the project down is critical, a rehost migration as opposed to a rewrite may be more advantageous for your organization.

  Contact us today to learn more about our experiences in this area.