1. Requirements Engineering Process
What is requirements engineering?
It is the process of discovering, analyzing, documenting and validating the requirements of the system
5 important activities:
Feasibility study
Requirements elicitation and analysis
Requirements validation
Requirements management

2. Requirement engineering

3. Feasibility studies
A feasibility study decides whether or not the proposed system is worthwhile
A short focused study that checks
If the system contributes to organisational objectives
If the system can be engineered using current technology and within budget
If the system can be integrated with other systems that are used
Doing the study
Consult information sources: managers, s/w engineers, end users…
Based on information collection (interviews, surveys, questionnaires…)
Should be short (2-3 weeks)

4. Feasibility study implementation
Based on information assessment (what is required), information collection and report writing
Questions for people in the organisation
What if the system wasn’t implemented?
What are current process problems?
How will the proposed system help?
Is new technology needed? What skills?

5. Feasibility study implementation
What will be the integration problems?
What facilities must be supported by the system?
What is the risk associated with cost and schedule?
What are the potential disadvantages/advantages?
Are there legal issues?
Are there issues linked with the fact that this is an offshore project?

6. Requirements Elicitation and analysis
Sometimes called requirements elicitation or requirements discovery
Involves technical staff working with customers to find out about the application domain, the services and the system’s operational constraints
May involve end-users, managers, engineers involved in maintenance, domain experts, trade unions, etc. These are called stakeholders

7. Problems of requirements analysis
Stakeholders don’t know what they really want
Stakeholders express requirements in their own terms
Different stakeholders may have different requirements
Organisational and political factors may influence the system requirements
The requirement changes during the analysis process.

8. Requirement elicitation and analysis process
Requirement discovery
Requirement classification and organization
Requirement prioritization and negotiation
Requirement documentation

9. Activities are
Requirement discovery-process of interacting with stakeholders to collect their requirements.
Requirement classification and organization – takes the unstructured collection of requirements,groups related requirements and organizes them.
Requirement prioritization and negotiation – prioritizing requiremetns and finding and resolving requirements conflicts through negotiation .
Requirement documentation –requirements are documented and given as input into next round of the spiral .

10. Requirements discovery
It is the process of gathering information about the proposed and existing systems and distilling the user and system requirements from this information.
Sources of information during this phase include documentation, system stakeholders and specification of similar systems.

11. Different stakeholders for a bank ATM
For example
Different stakeholders for a bank ATM
Bank customers
Representatives of other banks
Hardware and software maintenance engineers
Marketing department
Bank managers and counter staff
Database administrators and security staff
Communications engineers
Personnel department
Elicitation and analysis
Viewpoint oriented elicitation

12. Ethnography
It is an observational technique that can be used to understand social and organizational requirements.
Ethnography is particularly effective at discovering two types of requirements.
1.Requirements that are derived from the way in which people actually work.
2.Requirements that are derived from cooperation and awareness of other people’s activities.

13. Requirements validation
Concerned with demonstrating that the requirements define the system that the customer really wants
Requirements error costs are high so validation is very important

14. Requirements checking includes
Validity Check. The system should provide the functions which best support the customer’s needs.
Consistency Check. requirements in the document should not conflict.
Completeness Check.The requirements document should include requirements,which define all functions and constraints required by the customer.
Realism Check.The requirements can be implemented with given available budget and technology.
Verifiability.The delivered system should meet specified requirement.

15. Requirements validation Techniques can be used. 1
Requirements validation Techniques can be used. 1.Requirements reviews – The requirements are analyzed systematically by a team of reviewers. Reviewers may also check for Verifiability-Is the requirements testable? Comprehensibility- Is the requirement properly understood by the end users? Traceability- Is the origin of the requirement clearly stated? Adaptability- Is the requirement adaptable? 2.Prototyping – The customers and end users can experiment with this model to see if it meets their real needs. 3.Test case generation–Requirements should be testable.

16. Requirements Management
It is the process of understanding and controlling changes to the requirements during the requirements engineering process and system development.
The requirements for large systms are always changing.

17. As the requirement definition is developed, you normally develop a better understanding of user’s needs.
Initial requirements
Changed understanding of problem
Initial understanding of problem
Changed requirements
Time
Requirements Evolution

18. Enduring and volatile requirements
Enduring requirements. These are the stable requirements derived from the core activity of the customer organization. E.g. a hospital will always have doctors, nurses, etc. May be derived from domain models
Volatile requirements. These are requirements which change during development process or when the system is in use. In a hospital, requirements may be derived from government health-care policies.

19. Requirements management includes planning and change management.
Requirements management planning: Planning is a first stage in the requirement management process.
You have to decide on :
Requirements identification: The requirements are individually identified.
A change management process: This is the set of activities to assess the impact and cost of changes.
Traceability policies: These policies define the relationships between requirements and between the requirements and the system design.
CASE tool support: Tools that may be used the range from requirement management system to spreadsheets and simple database systems.
Requirements management
Enduring and volatile requirements
Requirements management planning

20. Traceability Source traceability information
There are three types of traceability information that may be maintained:
Source traceability information
Links the requirements to stakeholders who proposed these requirements
Requirements traceability information
Links dependent requirements within the requirements document.
Design traceability information
Links the requirements to the design modules where these requirements are implemented.

21. Requirements change management
ssss
Identified problem
Problem analysis and change specification
Change analysis and costing
Change implementation
Revised requirements

22. Requirements change management
Should apply to all proposed changes to the requirements
Principal stages
Problem analysis and change specification. Requirements problems and propose changes are analyzed.
Change analysis and costing. Effects and costs of change are Assessed on requirements
Change implementation. Requirements document ,system design and implementation are Modified.