Simple service architecture Introduction
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To be able to interoperate in the information viewpoint, two systems must be information model interoperable. To achieve information model interoperability the two systems must be both syntactically interoperable and
semantically interoperable:
Syntactically interoperable – Two systems are syntactically interoperable if they use the same structure for the information that flows in the systems and is processed by the systems.
Semantically interoperable – Two systems are semantically interoperable if they have a common understanding of the semantics of the information that flows in the systems and is processed by the systems.
The common structural models being defined by the information models address syntactic interoperability. In the ISO 19100 suite of standards the models are based on a generic feature model, which allows for representation of
various types of features, all having the same structure. To achieve semantic interoperability for feature types it is in addition necessary to match or make mappings between feature type definitions from feature type catalogues.
The issues of such information model interoperability will not be addressed in this International Standard.
The information viewpoint in ISO RM-ODP describes the information that flows in a system and is processed by a system. It focuses on the structuring of semantic information, typically the information that will be stored in a
database and communicated between the components of a system. An information model is used to describe the information viewpoint. This information model defines the structure and semantics of the information used in
system by defining objects, their properties and their relationships.
The information viewpoint is also concerned with the semantics of the information processing. Each particular service will need to define its syntactical interfaces through operations and its semantics through description of the
meaning of the operations and their legal sequencing. The latter can be done through pre- and post-conditions and invariants in OCL, and by UML state diagrams.
This section contains a description of a taxonomy of various services. There exist multiple possible taxonomies for services, based on various classification dimensions. The one that is used here is based on the extended OSE
model. The purpose of defining a taxonomy in this International Standard is to have one way of identifying geographic extensions to various existing service types. It is not intended to be the only taxonomy to be used in the
context of geographic services.
The work of identifying required services for geographic information standardization shall categorize if a needed service is GIS specific or more IT general, and which of the 6 service domains it belongs to. The processing
services domain will typically contain a variety of application-area GI specific services.
The next sections will describe typical IT Services and then show some possible geographic services in each of the six service domains.