WHAT IS THE DIFFERENCE BETWEEN IDEF1X AND EXPRESS-G DATA MODELLING METHODS

Hi mcgihhn3-ga,

Thanks for your interesting question...let's start by looking at
IDEFIX:

IDEFIX

The IDEF1 Information Modeling Method

IDEF1 was designed as a method for both analyzing and communicating
the structure and semantics of information within a system for the
establishment of system requirements.  IDEF1 is generally used to:

1. Identify what information is currently managed in a real-world
system.  An IDEF1 model of an information system includes not only the
automated system components, but also non-automated objects such as
people, filing cabinets, telephones, etc.
2. Identify the rules for governing the management of the information.
 The simple graphical conventions used in IDEF1 models allow modelers
to distinguish between real-world objects and the physical or abstract
associations maintained between real-world objects
3. Identify deficiencies in the current management of the information.
IDEF1 models capture the data structure of principles for acquiring,
applying, and managing that information.
4. Specify what information will be managed in a TO-BE implementation.
The IDEF1X Data Modeling Method

IDEF1X is fundamentally a method for designing relational databases.
The methodology supports a syntax designed for the development of a
conceptual schema of real-world systems.  A conceptual schema is a
single, integrated definition of the system data that is unbiased
towards any single application and independent of application access
and physical storage.  As a result, IDEF1X is most useful for logical
database design after the information requirements are known and the
decision to implement a relational database has been made (functions
better served by the IDEF1 method).  Hence, the IDEF1X system
perspective is focused on the actual data elements in a relational
database.

For example, in contrast to object-oriented systems, IDEF1X requires
that the modeler designate a key class to distinguish one entity from
another.  In addition, in situations where more than one attribute or
set of attributes will serve equally well for individuating IDEF1X
entities, the modeler must designate one as the primary key and list
all others as alternate keys.  Explicit foreign key labeling is also
required.  The resulting IDEF1X models are intended to be used as a
blueprint for the logical database design and implementation of that
design.

Why Use IDEF1X?

1. Useful in determining when information voids are the cause of a
problem
2. Consistent, extensible, and transformable 
3. Provides consistent mapping and definition of enterprise data 

Benefits of IDEF1X Analysis

1. Separate Facts from Folklore 
2. Discover underlying cause for problems 
3. Use directly as requirements 
4. Implement results with policy or procedure change 

Why Develop an IDEF1X Model?

1. Determine information resource management needs and requirements 
2. Depict what information is collected, stored, and managed 
3. Depict the rules governing the management of information 
4. Validate the concepts in the associated IDEF0 model 
5. Leverage information  to achieve a competitive advantage 

http://www.step.co.kr/training/IDEF1x_English.doc

EXPRESS-G

"EXPRESS G is a diagrammatic modeling notation for the purpose of an
object–oriented information modeling. This notation is based on the
standardized EXPRESS-G notation, which is itself described in ISO
10303-11: Industrial
Automation Systems – Product Data Representation and Exchange – Part
11: Description Methods: The EXPRESS Language Reference Manual."

http://tc3.iec.ch/txt/xpress.pdf

Express-G Overview :

"Graphical notation for a subset of EXPRESS 
Originally designed for documentation 
Presents results of a data modeling activity 
Software support -- EXPRESS-G used as a modeling technology"

http://www.okstate.edu/ind-engr/step/WEBFILES/Presentations/Html/p5/tsld065.htm

Since the above link is part of a slideshow you can click the "next
slide" links to get the rest of the Express-G information there.

I hope that helps answer your question...if you have any questions
regarding the information above please feel free to post a
clarification and I will respond in a timely manner :)

Cheers!

answerguru-ga
Google Answers Researcher

---

Request for Answer Clarification by mcgihhn3-ga on 25 Dec 2002 12:55 PST

thanks for your answer but can u tell me the main differences between
the two methods,if i have to choose one of these methods for my work
what are the bases to do so

---

Clarification of Answer by answerguru-ga on 25 Dec 2002 13:03 PST

Choosing the most appropriate data modeling technique depends on what
type of work you are going to use it for...the main basic difference
is that IDEFIX is not an object oriented model, whereas EXPRESS-G does
use object oriented concepts.

Since your question didn't really identify that you were making a
choice between the two methods, it is best if you post another
question if where you can state your intended use and request an
analysis for which method is best for your purposes. You can reference
the researcher to this question if you like :)

Thanks,

answerguru-ga