Service Abstractions
We must be careful to which service abstraction we refer:
general service
is a service for which the
provider has not been instantiated. This service may be
defined at various levels of abstraction, depending upon purpose.
The
particular service
is a service with the
provider instantiated.
The
service instance
is a completely specified service
with both the provider and consumer specified.
The
service performance
(or execution), of a
service instance
should cause some change of state to occur according to the
service agreement.
Service agreements may include that some conditions must
be met before the service will be performed.
Creation of an instance
of a new service is special:
the agreement may be the acceptance of a request from a consumer to
a provider.
It's often easiest to talk in terms of a service instance as long
as we keep in mind the other abstractions.
©2012
Charles Petrie - permission to reproduce widely with attribution.