Sandwich Model in SE

Requirement and Modeling
or
Sandwich Model

                             It is important to understand the relationship between requirement management and system modeling.They are mutually supportive activities that should not be equated.We can compare this relationship  to the terminology 'SANDWICH'.

                             In this analogy,Requirement Management is the "Bread & butter" of development cycle.The "Filling" is provided by the system modeling layer explains the analysis and design that has led to the subsequent layers of requirement.Some People talk about the requirement modeling. This is a misnomer.You infact model the system design, not requirement.
                         

                             'Modeling' supports the design activity and is where most of the creative work takes place. It assists the engineer in understanding enough of the system to decompose the requirements at a particular level into the next level down. The requirements themselves are a complete snapshot of what is required a teach level in increasing level of details.

Requirement and modeling

                                  A model is an abstraction of a system that deliberately focuses on some aspects of a system to the exclusion of others. Models exist the requirement engineers in analyzing  this requirements at a particular level so as to:

• Communicate with the customer and improve mutual understanding of the system to be developed.
• Determine how to satisfy the requirements.