1 Specification of IT Systems Mandatory Exercise Week 5 Jonas B. Jorgensen, Rune Simonsen, Torsten Aaboe Andersen, Jesper G. Jensen,

2 Ex. 1: Context diagram

3  Include in the context the entities of the composite system that jointly with the SuD achieves the goals of the composite system. (door, card reader, card, card printer, janitor, administrative worker)  Include in the context the entities in which the SuD attempts to cause a desired effect.(card reader, door)  Include in the context the entities from whom the SuD receives the information it needs to achieve its desired affect.(janitor, card reader)

4 Ex. 2: Requirement level decomposition diagram

5  We have a Von Neumann architecture with a combination of Functional Decomposition and Communication Oriented Decomposition.

6 Ex. 2: Requirement level decomposition diagram  Functional decomposition chosen because:  Validating a card and an access request is a pure function of the card input and the information in the database.  Validating user creation/editing input to the system is a pure function of the input data and rules specified.  Validating access rights input to the system is a pure function of the input data

7 Ex. 2: Requirement level decomposition diagram  Communication Oriented Decomposition chosen because:  We have chosen a device-oriented decomposition as external devices are an important part of the the system and this architecture makes it easy to show communication with these. These are Card Reader, Card Printer and Door.  The Janitor interface is an example of a user-oriented decomposition.

8 Ex. 3  The functionality provided by the previous diagrams corresponds to the functionality described in the function refinement tree.