Select service system solutions from alternative solutions.

Alternative solutions and their relative merits are considered in advance of selecting a solution. Key requirements (including quality attribute requirements), design issues, and constraints are established for use in alternative solution analysis. Architectural features that provide a foundation for service system improvement and evolution are considered.

Refer to the Decision Analysis and Resolution process area for more information about analyzing possible decisions using a formal evaluation process that evaluates identified alternatives against established criteria.

A potentially ineffective approach to implementing this practice is to generate solutions that are based on only the way services have been delivered in the past. It is important to consider alternatives that represent different ways of allocating and performing necessary functions (e.g., manual vs. automated processes, end user vs. service delivery staff responsibilities, prescheduled vs. on-the-fly service request management).

Components of the service system, including service delivery and support functions, can be allocated to external suppliers. As a result, prospective supplier agreements are investigated. The use of externally supplied components is considered relative to cost, schedule, performance, and risk. Externally supplied alternatives can be used with or without modification. Sometimes such items can require modifications to aspects such as interfaces or a customization of some of their features to better meet service or service system requirements.

Refer to the Supplier Agreement Management process area for more information about managing the acquisition of products and services from suppliers.

Example Work Products

1.    Alternative solution screening criteria

2.    Selection criteria

3.    Service system component selection decisions and rationale

4.    Documented relationships between requirements and service system components

5.    Documented solutions, evaluations, and rationale

Subpractices

1.    Establish defined criteria for selection.

2.    Develop alternative solutions.

The development of alternative solutions can involve the use of architectural patterns, reuse of components, investigation of commercial off-the-shelf (COTS) solutions, service outsourcing, and consideration of technology maturation and obsolescence.

3.    Select the service system solutions that best satisfy the criteria established.

The selection is based on an evaluation of alternatives using the defined criteria. In high-risk situations, simulations, prototypes, or pilots can be used to assist in the evaluation.

Selecting service system solutions that best satisfy the criteria is the basis for allocating requirements to the different aspects of the service system. Lower level requirements are generated from the selected alternative and used to develop the design of service system components. Interface requirements among service system components are described.