Semantic data model
Encyclopedia
Software engineering
Software Engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software, and the study of these approaches; that is, the application of engineering to software...
has various meanings:
- It is a conceptual data model in which semantic information is included. This means that the model describes the meaning of its instances. Such a semantic data modelData modelA data model in software engineering is an abstract model, that documents and organizes the business data for communication between team members and is used as a plan for developing applications, specifically how data is stored and accessed....
is an abstraction that defines how the stored symbolSymbolA symbol is something which represents an idea, a physical entity or a process but is distinct from it. The purpose of a symbol is to communicate meaning. For example, a red octagon may be a symbol for "STOP". On a map, a picture of a tent might represent a campsite. Numerals are symbols for...
s (the instance data) relate to the real world. - It is a conceptual data model that includes the capability to express information that enables parties to the information exchange to interpret meaning (semantics) from the instances, without the need to know the meta-model. Such semantic models are fact oriented (as opposed to object oriented). Facts are typically expressed by binary relations between dataDataThe term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
elements, whereas higher order relations are expressed as collections of binary relations. Typically binary relations have the form of triples: Object-RelationType-Object. For example: the Eiffel TowerParis.
Typically the instance data of semantic data models explicitly include the kinds of relationships between the various data elements, such as
The second kind of semantic data models are usually meant to create semantic databases. The ability to include meaning in semantic databases facilitates building distributed databases that enable applications to interpret the meaning from the content. This implies that semantic databases can be integrated when they use the same (standard) relation types. This also implies that in general they have a wider applicability than relational or object oriented databases.
Overview
The logical data structure of a database management systemDatabase management system
A database management system is a software package with computer programs that control the creation, maintenance, and use of a database. It allows organizations to conveniently develop databases for various applications by database administrators and other specialists. A database is an integrated...
(DBMS), whether hierarchical
Hierarchical model
A hierarchical database model is a data model in which the data is organized into a tree-like structure. The structure allows representing information using parent/child relationships: each parent can have many children, but each child has only one parent...
, network
Network model
The network model is a database model conceived as a flexible way of representing objects and their relationships. Its distinguishing feature is that the schema, viewed as a graph in which object types are nodes and relationship types are arcs, is not restricted to being a hierarchy or lattice.The...
, or relational
Relational model
The relational model for database management is a database model based on first-order predicate logic, first formulated and proposed in 1969 by Edgar F...
, cannot totally satisfy the requirements
Requirements analysis
Requirements analysis in systems engineering and software engineering, encompasses those tasks that go into determining the needs or conditions to meet for a new or altered product, taking account of the possibly conflicting requirements of the various stakeholders, such as beneficiaries or users...
for a conceptual definition of data, because it is limited in scope and biased toward the implementation strategy employed by the DBMS. Therefore, the need to define data from a conceptual view
Three schema approach
The three-schema approach, or the Three Schema Concept, in software engineering is an approach to building information systems and systems information management from the 1970s...
has led to the development of semantic data modeling techniques. That is, techniques to define the meaning of data within the context of its interrelationships with other data. As illustrated in the figure. The real world, in terms of resources, ideas, events, etc., are symbolically defined within physical data stores. A semantic data model is an abstraction which defines how the stored symbols relate to the real world. Thus, the model must be a true representation of the real world.
According to Klas and Schrefl (1995), the "overall goal of semantic data models is to capture more meaning of data by integrating relational concepts with more powerful abstraction concepts known from the Artificial Intelligence
Artificial intelligence
Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...
field. The idea is to provide high level modeling primitives as integral part of a data model in order to facilitate the representation of real world situations".
History
The need for semantic data models was first recognized by the U.S. Air Force in the mid-1970s as a result of the Integrated Computer-Aided ManufacturingIntegrated Computer-aided manufacturing
Integrated Computer-Aided Manufacturing is a US Air Force program to develop tools, techniques, and processes to support manufacturing integration and has influenced the computer-integrated manufacturing and computer-aided manufacturing project efforts of many companies.The ICAM program was...
(ICAM) Program. The objective of this program was to increase manufacturing productivity through the systematic application of computer technology. The ICAM Program identified a need for better analysis and communication techniques for people involved in improving manufacturing productivity. As a result, the ICAM Program developed a series of techniques known as the IDEF (ICAM Definition) Methods which included the following:
- IDEF0IDEF0IDEF0 is a function modeling methodology for describing manufacturing functions, which offers a functional modeling language for the analysis, development, reengineering, and integration of information systems; business processes; or software engineering analysis.IDEF0 is part of the IDEF family...
used to produce a “function model” which is a structured representation of the activities or processes within the environment or system. - IDEF1 used to produce an “information model” which represents the structure and semantics of information within the environment or system.
- IDEF1XIDEF1XIDEF1X is a data modeling language for the developing of semantic data models. IDEF1X is used to produce a graphical information model which represents the structure and semantics of information within an environment or system.IDEF1X permits the construction of semantic data models which may serve...
is a semantic data modeling technique. It is used to produce a graphical information model which represents the structure and semantics of information within an environment or system. Use of this standard permits the construction of semantic data models which may serve to support the management of data as a resource, the integration of information systems, and the building of computer databases.
- IDEF1X
- IDEF2 used to produce a “dynamics model” which represents the time varying behavioral characteristics of the environment or system.
During the 1990s the application of semantic modelling techniques resulted in the semantic data models of the second kind. An example of such is the semantic data model that is standardised as ISO 15926
ISO 15926
The ISO 15926 is titled: "Industrial automation systems and integration—Integration of life-cycle data for process plants including oil and gas production facilities" is a standard for data integration, sharing, exchange, and hand-over between computer systems.This title is regarded too...
-2 (2002), which is further developed into the semantic modelling language Gellish
Gellish
Gellish is a controlled natural language, also called a formal language, in which information and knowledge can be expressed in such a way that it is computer-interpretable, as well as system-independent. Gellish is a structured subset of natural language that is suitable for information modelling...
(2005). The definition of the Gellish language is documented in the form of a semantic data model. Gellish itself is a semantic modelling language, that can be used to create other semantic models. Those semantic models can be stored in Gellish Databases, being semantic databases.
Applications
A semantic data model can be used to serve many purposes. Some key objectives include:- Planning of Data Resources: A preliminary data model can be used to provide an overall view of the data required to run an enterprise. The model can then be analyzed to identify and scope projects to build shared data resources.
- Building of Shareable Databases: A fully developed model can be used to define an application independent view of data which can be validated by users and then transformed into a physical database design for any of the various DBMS technologies. In addition to generating databases which are consistent and shareable, development costs can be drastically reduced through data modeling.
- Evaluation of Vendor Software: Since a data model actually represents the infrastructure of an organization, vendor software can be evaluated against a company’s data model in order to identify possible inconsistencies between the infrastructure implied by the software and the way the company actually does business.
- Integration of Existing Databases: By defining the contents of existing databases with semantic data models, an integrated data definition can be derived. With the proper technology, the resulting conceptual schema can be used to control transaction processing in a distributed database environment. The U.S. Air Force Integrated Information Support System (I2S2) is an experimental development and demonstration of this type of technology applied to a heterogeneous DBMS environment.
See also
- Conceptual schemaConceptual schemaA conceptual schema or conceptual data model is a map of concepts and their relationships. This describes the semantics of an organization and represents a series of assertions about its nature...
- Entity-relationship modelEntity-relationship modelIn software engineering, an entity-relationship model is an abstract and conceptual representation of data. Entity-relationship modeling is a database modeling method, used to produce a type of conceptual schema or semantic data model of a system, often a relational database, and its requirements...
- Information modelInformation modelAn 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...
- Relational Model/TasmaniaRelational Model/TasmaniaRelational Model/Tasmania was published by E.F. Codd in 1979 and is the name given to a number of extensions to his original relational model published in 1970. The overall goal of the RM/T was to define some fundamental semantic units, at "atomic" and "molecular" levels, for data modelling...
- Three schema approachThree schema approachThe three-schema approach, or the Three Schema Concept, in software engineering is an approach to building information systems and systems information management from the 1970s...
- QuakeSimQuakeSimQuakeSim is a NASA project for modeling earthquake fault systems. It was started in 2001 with NASA funding as a follow up to the General Earthquake Models initiative. The multi-scale nature of earthquakes requires integrating data types and models to fully simulate and understand the earthquake...
Further reading
- Database Design - The Semantic Modelling Approach
- Johan ter Bekke (1992). Semantic Data Modelling. Prentice Hall.
- Alfonso F. Cardenas and Dennis McLeod (1990). Research Foundations in Object-Oriented and Semantic Database Systems. Prentice Hall.
- Peter Gray, Krishnarao G. Kulkarni and, Norman W. Paton (1992). Object-Oriented Databases: A Semantic Data Model Approach. Prentice-Hall International Series in Computer Science.
- Michael Hammer and Dennis McLeod (1978). "The Semantic Data Model: a Modeling Mechanism for Data Base Applications." In: Proc. ACM SIGMOD Int’l. Conf. on Management of Data. Austin, Texas, May 31 - June 2, 1978, pp. 26-36.
External links
- Semantic Data Models Course – Object Oriented Datatabase Systems, by Colin Jack & Colin Keillor (2008).
- Semantic Data Modeling Johan ter Bekke tribute site.