Information model

An information model in software engineering is a representation of concepts, relationships, constraints, rules, and operations to specify data semantics for a chosen domain of discourse. It can provide sharable, stable, and organized structure of information requirements for the domain context. Y. Tina Lee (1999). [http://www.mel.nist.gov/msidlibrary/doc/tina99im.pdf "Information modeling from design to implementation"] National Institute of Standards and Technology.]

Overview

The term "information model" in general is used for models of individual things, such as facilities, buildings, process plants, etc. In those cases the concept is specialised to Facility Information Model, Building Information Model, Plant Information Model, etc. Such an information model is an integration of a model of the facility with the data and documents about the facility.

Within the field of software engineering and data modeling an information model is an abstract, formal representation of entity types that includes their properties, relationships and the operations that can be performed on them. The entity types in the model may be kinds of real-world objects, such as devices in a network, or they may themselves be abstract, such as for the entities used in a billing system. Typically, they are used to model a constrained domain that can be described by a closed set of entity types, properties, relationships and operations.

An information model provides formalism to the description of a problem domain without constraining how that description is mapped to an actual implementation in software. There may be many mappings of the information model. Such mappings are called data models, irrespective of whether they are object models (e.g. using UML), entity relationship models or XML schemas.

History

In 1976, an Entity Relationship graphic notation was introduced to develop relational data models [ Peter Chen (1976). "The Entity-Relationship Model - Towards a Unified View of Data". In: "ACM Transactions on database Systems", Vol. 1, No.1, March, 1976.] Since then, languages for information models have continued to evolve. Some examples are the Integrated Definition Language 1 Extended (IDEF1X) , the EXPRESS Language and the Unified Modeling Language (UML).

The ICAM Definition (IDEF) Language was developed from the U.S. Air Force ICAM Program during the 1976 to 1982 timeframe. [D. Appleton Company, Inc. (1985). "Integrated Information Support System: Information Modeling Manual, IDEF1 - Extended (IDEF1X)". ICAM Project Priority 6201, Subcontract #013-078846, USAF Prime Contract #F33615-80-C-5155, Wright-Patterson Air Force Base, Ohio, December, 1985.] The objective of the ICAM Program was to increase manufacturing productivity through the systematic application of computer technology. IDEF includes three different modeling methods: IDEF0, IDEF1, and IDEF2 for producing a functional model, an information model, and a dynamic model respectively. IDEF1X is an extended version of IDEF1. The language is in the public domain. It is a graphical representation and is designed using the ER approach and the relational theory. It is used to represent the “real world” in terms of entities, attributes, and relationships between entities. Normalization is enforced by KEY Structures and KEY Migration. The language identifies property groupings (Aggregation) to form complete entity definitions.

EXPRESS was created as ISO 10303-11 for formally specifying information requirements of product data model. It is part of a suite of standards informally known as the STandard for the Exchange of Product model data (STEP). It was first introduced in the early 1990s. [ ISO 10303-11:1994(E), Industrial Automation Systems and Integration - Product Data Representation and Exchange - Part 11: The EXPRESS Language Reference Manual. ] [ D. Schenck and P. Wilson (1994). "Information Modeling the EXPRESS Way." Oxford University Press, New York, NY, 1994.] The language is a textual representation. In addition, a graphical subset of EXPRESS called EXPRESS-G is available. EXPRESS is based on programming languages and the O-O paradigm. A number of languages have contributed to EXPRESS. In particular, Ada, Algol, C, C++, Euler, Modula-2, Pascal, PL/1, and SQL. EXPRESS consists of language elements that allow an unambiguous object definition and specification of constraints on the objects defined. It uses SCHEMA declaration to provide partitioning and it supports specification of data properties, constraints, and operations.

UML is a modeling language for specifying, visualizing, constructing, and documenting the artifacts, rather than processes, of software systems. It was conceived originally by Grady Booch, James Rumbaugh, and Ivar Jacobson. UML was approved by the Object Management Group (OMG) as a standard in 1997. The language is non-proprietary and is available to the public. It is a graphical representation. The language is based on the objected-oriented paradigm. UML contains notations and rules and is designed to represent data requirements in terms of O-O diagrams. UML organizes a model in a number of views that present different aspects of a system. The contents of a view are described in diagrams that are graphs with model elements. A diagram contains model elements that represent common O-O concepts such as classes, objects, messages, and relationships among these concepts.

IDEF1X, EXPRESS, and UML all can be used to create a conceptual model, and each has its own characteristics. Although some may lead to a natural usage (e.g., implementation), one is not necessarily better than another. In practice, it may require more than one language to develop all information models when an application is complex. In fact, the modeling practice is often more important than the language chosen.

Standard sets of information models

The Distributed Management Task Force (DMTF) provides a standard set of information models for various enterprise domains under the general title of the Common Information Model (CIM). Specific information models are derived from CIM for particular management domains.

The TeleManagement Forum (TMF) has defined an advanced model for the Telecommunication domain (the Shared Information/Data model, or SID) as another. This includes views from the business, service and resource domains within the Telecommunication industry. The TMF has established a set of principles that a OSS integration should adopt, along with a set of models that provide standardized approaches.

The models interact with the information model (the Shared Information/Data model, or SID), via a process model (the enhanced Telecom Operation Map, or eTOM) and a life cycle model.

References

External links

* RFC 3198 - Terminology for Policy-Based Management
* [http://www.dmtf.org/ DMTF Homepage]
* [http://www.tmforum.org/ TMF Homepage]