Requirements Engineering

Requirements Engineering

1. User and system requirements

   • Tipically has two levels of details
     • User
       • It describe the service that systems should provide
       • It's usually written in natural language
       • They don't expect to see any level of detail
     • System
       • It needs more detail of systems services and operational constrains
       • This level is needd by developers
   • Differents level of detail is usefull
     • Developers needs exactly information about users needs
     • End-user need a generic abstracted written requirements

2. Process of gathering and defining services provided by system

   • It discover requirements
   • It's an iterative process
   • Is not a sequencial process
   • It focuses on assessing if systems are useful to the business
   • Convert requirements into formats
   • Requirements define that system customer wants

3. Software requirements has two classification's type

   • Functional
     • It covers main functions
     • It's expressing user requirements
     • Usually described in an abstract way
     • Describe input process
   • Non-functional
     • How many process can be handle by system
     • Security issues
     • programming languages and tools
     • Are often critical
     • Fail to meet non-functional requirements can mean the system fail
     • The constrains on functions provided by system
     • It should be measurable
       • Size
       • Properties
       • Robustness
       • Easy of use
       • Portability
   • Functional and non-functional are dependent
     • Non-functional often conflict, interact or generate other functional requeriment
     • Separate between them
       • Relationship between both may be hard
       • Non-functional are stated separately from functional
       • We should be explicity clear with requirements
     • Distinction between them
       • Distinction is not clear
       • It is difficult to separate

4. Feasibility report

   • A study to identify if system could be implemented
     • Technical skills
     • Schedule
     • If implementation is align with organization objectives
     • Current budget
   • The results of the study should be a report with recomendations to other implementations
   • This input is setting as preliminary business requirements