# SE2 - lesson 04
#### Elisabeta di Nitto
##### 15 October 2015
## Requirement analisys pt.II

The boundary between the world and the machine may vary

The purpose of a RE activity is:
- Identify the __goals__ of the project
- Explore alternative ways of satisfying the goals
- Evaluate strenght and risks of each alternative, to select the most appropriate

### Requirement Analisys and Specification Document - RASD

- It is used as a *baseline* for __software evaluation__

#### Stakeholders of the RASD
- Customers & users
- System analysts, requirements analysts
- Developers, Programmers
- Testers
- Project managers

It tipically has a __multilevel structure__, and it's defined by IEEE standard
1. __Introduction__
    - Purpose
    - Scope: Identifies the product and the application domain
    - Definitions, acronyms, abbreviations
    - Reference documents
    - Overview
2. __Overall Description__
    - Product perspecive: Describes all esxternal interfaces (system, user, hardware, ...)
    - Produt functions
3. __Specific Requirements__: the body of the document

### section 3: Specific Requirements

3.1 __External interface requirements__  
- 3.1.1 User interfaces
- 3.1.2 H

3.2 __Functional Requirements__  
3.3 __Performance Requirements__  
3.4 __Design Constraints__  
3.5 __Software System Attributes__  
3.6 __Other Requirements__

### Target qualities for a RASD

- __Completeness__
- __Pertinence__
- __Consistency__
- __Unambiguity__
- __Feasibility__
- __Comprehensibility__
- __Good Structuring__
- __Modifiability__
- __Traceability__

### Functional Requirements bad examples

> The system shall validate and accept credit cards and cashier's checks. High priority.

Two requirements are expressed together.

> The system shall process all mouse clicks very fast to ensure users do not have to wait

This requirement is not specific, it doesn't give a measure of "fast"

> The user must have Adobe Acrobat installed

It is a constraint, not a requirement.

### Types of requirements

- __Functional requirements__
- __Nonfunctional requirements__
- __Constraints__

While functional requirements have to be provided by the end user, Nonfunctional requirements are __independend of the application domain__

Nonfunctional requirements are also calles __QoS requirements__

### Project initiation

An important step is making an __Interview__ with the customers