Seven Types of Software Requirements.ppt
- 1. Type of Type of Software Requirements Software Requirements By: By: Maham Tariq Maham Tariq
- 2. 1. 1. Functional Requirements Functional Requirements 2. 2. Non-Functional Requirements Non-Functional Requirements 3. 3. Domain Requirements Domain Requirements 4. 4. Inverse Requirements Inverse Requirements 5. 5. Design and implementation constraints Design and implementation constraints 6. 6. Reliability Requirements Reliability Requirements 7. 7. Safety Requirements Safety Requirements Type of Type of Software Requirements Software Requirements
- 3. Functional and non-functional Functional and non-functional requirements requirements Functional requirements Functional requirements • Statements of Statements of services services or functions the system or functions the system should provide, how the system should should provide, how the system should react react to particular to particular inputs inputs and how the system should and how the system should behave behave in particular situations. in particular situations. Non-functional requirements Non-functional requirements • Define system properties and constraints e.g. Define system properties and constraints e.g. reliability, response time and storage reliability, response time and storage requirements. Constraints are I/O device requirements. Constraints are I/O device capability, system representations, etc. capability, system representations, etc. • Non-functional requirements may be more Non-functional requirements may be more critical than functional requirements critical than functional requirements. If these . If these are not met, the system is useless. are not met, the system is useless.
- 4. Functional requirements Functional requirements Describe functionality or system services Describe functionality or system services Depend on the type of software, expected Depend on the type of software, expected users and the type of system where the users and the type of system where the software is used software is used Functional user requirements may be Functional user requirements may be high-level statements of what the system high-level statements of what the system should do but functional system should do but functional system requirements should describe the system requirements should describe the system services in detail services in detail
- 5. Examples of Examples of Functional Requirements Functional Requirements The user shall be able to search either all of The user shall be able to search either all of the initial set of databases or select a subset the initial set of databases or select a subset from it. from it. The system shall provide appropriate The system shall provide appropriate viewers for the user to read documents in viewers for the user to read documents in the document store. the document store. Every order shall be allocated a unique Every order shall be allocated a unique identifier (ORDER_ID) which the user shall identifier (ORDER_ID) which the user shall be able to copy to the account’s permanent be able to copy to the account’s permanent storage area. storage area.
- 6. Non-functional classifications Non-functional classifications Product requirements Product requirements • Requirements which specify that the delivered Requirements which specify that the delivered product must behave in a particular way e.g. product must behave in a particular way e.g. execution speed, reliability execution speed, reliability, etc. , etc. Organisational requirements Organisational requirements • Requirements which are a consequence of Requirements which are a consequence of organisational policies organisational policies and procedures e.g. and procedures e.g. process standards used, implementation process standards used, implementation requirements, etc. requirements, etc. External requirements External requirements • Requirements which arise from factors which Requirements which arise from factors which are external to the system and its development are external to the system and its development process e.g. inter-operate requirements, process e.g. inter-operate requirements, legislative requirements legislative requirements, etc. , etc. Note: Note: Interoperability is a property referring to the ability of diverse Interoperability is a property referring to the ability of diverse systems and organizations to work together (inter-operate) systems and organizations to work together (inter-operate)
- 7. Non-functional requirement types Non-functional requirement types Performance requirements Space requirements Usability requirements Efficiency requirements Reliability requirements Portability requirements Interoperability requirements Ethical requirements Legislative requirements Implementation requirements Standards requirements Delivery requirements Safety requirements Privacy requirements Product requirements Organizational requirements External requirements Non-functional requirements
- 9. Domain Requirements Domain Requirements Requirements that come from the Requirements that come from the application domain and reflect application domain and reflect fundamental characteristics of that fundamental characteristics of that application domain application domain( (sphere of influence sphere of influence) ) These can be both the functional or These can be both the functional or non-functional requirements. non-functional requirements.
- 10. Domain Requirements Domain Requirements Example-1: Example-1: In a commission-based sales In a commission-based sales businesses, there is businesses, there is no concept of no concept of negative commission. negative commission. However, if However, if care is not taken novice developers care is not taken novice developers can be developed systems, which can be developed systems, which calculate negative commission. calculate negative commission.
- 11. Domain Requirements Domain Requirements Example-2: Example-2: Banking domain has its own specific Banking domain has its own specific constraints, for example, most banks constraints, for example, most banks do do not allow over-draw not allow over-draw on most on most accounts, however, most banks allow accounts, however, most banks allow some accounts to be some accounts to be over-drawn. over-drawn.
- 12. Domain Requirements Domain Requirements These requirements, sometimes, are These requirements, sometimes, are not clearly mentioned not clearly mentioned Req. engineers find it difficult to Req. engineers find it difficult to convey domain requirements convey domain requirements So Domain experts get it properly. So Domain experts get it properly. Their absence can cause significant Their absence can cause significant dissatisfaction dissatisfaction
- 13. Domain Requirements Domain Requirements Domain requirements can impose Domain requirements can impose strict constraints on solutions. This strict constraints on solutions. This is particularly true for scientific and is particularly true for scientific and engineering domains engineering domains Domain-specific terminology can also Domain-specific terminology can also cause confusion cause confusion
- 15. Inverse Requirements Inverse Requirements They explain what the system shall They explain what the system shall not not do. do. Many people find it convenient to describe Many people find it convenient to describe their needs in this manner their needs in this manner. . These requirements indicate the unwanted These requirements indicate the unwanted needs of customers about certain aspects needs of customers about certain aspects of a new software product of a new software product
- 16. Inverse Requirements Inverse Requirements Example: Example: The system shall not use The system shall not use red color in red color in the user interface the user interface, whenever it is , whenever it is asking for inputs from the end-user asking for inputs from the end-user
- 17. Design and Implementation Design and Implementation Constraints Constraints
- 18. Design and Implementation Constraints Design and Implementation Constraints They are development guidelines They are development guidelines within which the designer must work within which the designer must work These requirements can seriously These requirements can seriously limit design and implementation limit design and implementation options. options. Can also have impact on human Can also have impact on human resources due to change in scope of resources due to change in scope of work. work.
- 19. Design and Implementation Design and Implementation Constraints Examples Constraints Examples The system shall be developed using The system shall be developed using the the Microsoft .Net platform Microsoft .Net platform. . The system shall be developed using The system shall be developed using open source tools and shall run on open source tools and shall run on Linux operating system. Linux operating system.
- 20. Safety Requirements Safety Requirements Safety requirements cover not only human Safety requirements cover not only human safety, but also equipment and data safety. safety, but also equipment and data safety. Human safety considerations include protecting Human safety considerations include protecting the operator from moving parts, electrical the operator from moving parts, electrical circuitry and other physical dangers. There may circuitry and other physical dangers. There may be special operating procedures, which if be special operating procedures, which if ignored may lead to a dangerous condition ignored may lead to a dangerous condition occurring. Equipment safety includes occurring. Equipment safety includes safeguarding the software system from safeguarding the software system from unauthorized access either electronically or unauthorized access either electronically or physically. An example of a safety requirement physically. An example of a safety requirement may be that a security monitor used in the may be that a security monitor used in the system. system. 20 20
- 21. Reliability Requirements Reliability Requirements Reliability requirements are those which the software Reliability requirements are those which the software must meet in order to perform a specific function must meet in order to perform a specific function under certain stated conditions, for a given period of under certain stated conditions, for a given period of time. time. The level of reliability requirement can be dependant The level of reliability requirement can be dependant on the type of system, i.e. the more critical or life on the type of system, i.e. the more critical or life threatening the system, the higher the level of threatening the system, the higher the level of reliability required. reliability required. Reliability can be measured in a number of ways Reliability can be measured in a number of ways including number of bugs per x lines of code, mean including number of bugs per x lines of code, mean time to failure. time to failure. 21 21