Evaluating the Environment
The migration solution you choose should be based on how an application fits into the overall IT environment. Consequently, you must evaluate the existing environment to determine both how the application meets business needs and its IT effectiveness.
Adequacy of meeting business needs relates to the application's ability to support the business functionality of the enterprise. Adequacy of meeting business needs can be defined as follows:
The time required to introduce new features
The ease of use of the application
The ability to support the functional requirements of the enterprise
The ability to support the future growth of the enterprise
Whereas the adequacy of meeting business needs relates to the application's ability to meet the current and projected functional needs of the enterprise, IT effectiveness measures the application's use of technology. IT effectiveness can be defined as:
Service level issues
The comparison of an application's IT effectiveness with the adequacy of meeting business needs is represented in the following figure.
FIGURE 0-2 Effectiveness Versus Business Needs
The x axis evaluates how well the application currently fulfills its function in the business process. The y axis rates its IT effectiveness in terms of cost, technological stability, dependencies, and other factors. To determine a migration solution for each of the applications within the enterprise, we recommend that you begin by plotting the applications that have the greatest impact on the business process within this framework.
The evaluation of the application can be very formal (for example, a complete TCO study), or it can be ad hoc. Typically, the Chief Financial Officer of the enterprise will have to agree with the evaluation prior to agreeing to a budget to support the migration. By systematically evaluating all applications with the same criteria, a comprehensive migration strategy can be developed that will include a number of different solutions, as illustrated in the example shown in the following figure.
FIGURE 0-3 Example Evaluation of Applications
Applications with the following characteristics should be treated as follows:
Applications that fall in the lower left quadrant are meeting business process needs and are highly effective with respect to IT; they probably should be maintained as they are.
Applications in the lower right quadrant have high IT effectiveness, but are not meeting business process needs; they should be enhanced, not migrated.
Applications that fall in the upper quadrants are the best candidates for migration. If they are meeting functional business process needs but are low in IT effectiveness (upper left quadrant), it is probably time to move them to a new environment. If they exhibit low IT effectiveness and lack functionality (upper right quadrant), it is probably time for the applications to be rearchitected.
FIGURE 0-3 illustrates how different applications (for example, payroll, inventory, and order entry applications) map to different migration solution spaces. For example:
Order entry should be refronted because it relies on an antiquated user interface.
The implementation and deployment of the payroll application is highly effective from an IT perspective and adequately meets business needs. It should remain where it is and be connected to new applications in the environment, as they are implemented, using connectors or adapters.
The inventory application should be rehosted because the functionality it provides meets business needs, but there are issues with the hardware where it is implemented.
The terms "refront" and "rehost" are defined in detail in the following section.