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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 how effective it is.
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 :
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:
The comparison of an application's IT effectiveness with the adequacy of meeting business needs is represented in the following figure.
Figure 3-2. 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, you should begin by plotting the applications that have the greatest impact on the business process within this framework.
The evaluation of the application can be 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 before 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.
Applications with the following characteristics should be treated as follows:
FIGURE 3-3 illustrates how different applications (for example, payroll, inventory, and order entry applications) map to different migration solution spaces. For example:
Figure 3-3. Example Evaluation of Applications
The terms "refront" and "rehost" are defined in detail in the following section.
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