Definition of Service
Definition Last Updated 17-Dec-2015 12:51
A service is a exercised by a performer at the request of another entity; it is usually assumed that the requesting entity is a direct beneficiary of the service performance but it is not necessarily the case. Service contrasts with function in that a function is the exercise of a capability at the performer’s own volition or that of the entity of which the performer is a part, thus a request by one department to another to do X may count as an inter-departmental service from the perspective of the departments and a business function from the perspective of the business as a whole.
The definition of service as a relationship avoids all such conflicts:
Since a service cannot be requested unless the would-be requester knows where to obtain performance of the underlying capability, capabilities offered for performance on behalf of others must be advertised and it is shorter and easier to offer “Service X” than “to do X on your behalf”.
It is not the case that all services are always available to all, thus at the highest level of abstraction a service is defined in terms of descriptions of qualifying entities and
Service level derives directly from measures of the performer’s capability strength and breadth.
Service contracts provide specific details of offered (include measures of success) and conditions of eligibility for requesters
Services are expressed as relationships of the form:
[Service] is the performance by [performer] of [capability] requested by [entity] ≠ [performer]
[Performer] offers performance of [capability] as [service] to (qualifying) [entity] ≠ [performer]