A black-box representation of a persisted data
structure that is not exposed using services. The internals of the data structure are not
revealed. An artifact such as a database table is considered to be part of the internal design of a service
provider and therefore not something that you would want to expose in its specification. Actual data persistence
structures might change in shape (possibly for non-functional reasons such as performance) without affecting clients of
the specification.
Information types are very useful in service operation pre-condition and post-condition specifications as they
provide a mechanism to refer to changes in state in a black-box fashion.
Information types commonly are derived from domain types.
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