Analysis all, Exams of Advanced Computer Architecture

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• Requirements Analysis-
  • Last Update: Monday September 1,

Contents

 Requirements Analysis: “What” and “How”?  (^) Unified Process  (^) OO Analysis and Design  (^) Basics  (^) UML  (^) Actors, Use cases

Requirements Analysis [2] 

C- and D-Requirements

 (^) C-: Customer wants and needs; expressed in language understood by the customer.  (^) D-: For the developers; may be more formal.

Requirements Analysis [3] Why document requirements?

• (^) Serves as a contract between the customer and the developer.
• (^) Serves as a source of test plans.
• (^) Serves to specify project goals and plan development cycles and increments.

Requirements Analysis [5]  (^) C-requirements:  (^) Use cases expressed individually and with a use case diagram. A use case specifies a collection of scenarios.  (^) Sample use case: Process sale.  (^) Data flow diagram :  (^) Explains the flow of data items across various functions. Useful for explaining system functions. [Example on the next slide.]  (^) State transition diagram :  (^) Explains the change of system state in response to one or more operations. [Example two slides later.]  (^) User interface : Generally not a part of requirements analysis though may be included.

Data Flow Diagram Get employee file Total pay Deduct taxes Net pay Issue paycheck Regular hours Overtime hours ID Worker Check Company records Employee Record Tax rates Pay rate Weekly

• (^) pay Pay Overtime pay

Overtime rate

Requirements Analysis [6]  (^) D-requirements:  (^) Organize the D-requirements.  (^) Create sequence diagrams for use cases:  (^) Obtain D-requirements from C-requirements and customer.  (^) Outline test plans  Inspect  (^) Validate with customer.  (^) Release:

Requirements Analysis [7]

Organize the D-requirements: Functional requirements The blood pressure monitor will measure the blood pressure and display it on the in-built screen. Non-functional requirements Performance The blood pressure monitor will complete a reading within 10 seconds. Reliability The blood pressure monitor must have a failure probability of less than 0.01 during the first 500 readings.

Requirements Analysis [9]

Properties of D-requirements:  (^) Traceability: Functional requirements D-requirement  inspection report  design segment  code segment  code inspection report  test plan  test report  (^) Traceability: Non-Functional requirements (a) Isolate each non-functional requirement. (b) Document each class/function with the related non-functional requirement.

Requirements Analysis [10]  (^) Testability It must be possible to test each requirement. Example?  (^) Categorization and prioritization..next slide

Requirements Analysis [11]  (^) Completeness Self contained, no omissions.  Error conditions State what happens in case of an error. How should the implementation react in case of an error condition?

Consistency of Requirements

 (^) Different requirements must be consistent. R5.4: When the vehicle is cruising at a speed greater than 300 mph, a special “watchdog” safety mechanism will be automatically activated. Example: R1.2: The speed of the vehicle will never exceed 250 mph.

What is Analysis and Design?  Analysis - investigation of the problem (what);  (^) Design - conceptual solution to fulfill the requirements (how); how will the system do what it is intended to do.  (^) What does the system do?  (^) Investigation of the problem.  (^) What (conceptual) solution will full the requirements

What is OO analysis and design?  (^) Essence of OO analysis - consider a problem domain from the perspective of objects (real world things, concepts)  (^) Essence of OO design - define the solution as a collection of software objects (allocating responsibilities to objects)