Software Engineering Principles and Practices

Software Engineering

1. Department of Collegiate and Technical Education Week -6 Requirement Engineering & Modeling Software Engineering Principles and Practices Computer Science and Engineering Session 02 Computer Science & Engineering – 20CS44P

2. Computer Science & Engineering – 20CS44P REQUIREMENT ENGINEERING PROCESS Requirements Engineering Processes may include four high-level activities. Feasibility study : These focus on assessing if the system is useful to the business Elicitation and Analysis : discovering requirements S pecification : converting these requirements into some standard form and V alidation : checking that the requirements actually define the system that the customer wants

3. Computer Science & Engineering – 20CS44P

4. Computer Science & Engineering – 20CS44P Feasibility study A feasibility study is a short, focused study that should take place early in the RE process. It should answer three key questions: Does the system contribute to the overall objectives of the organization? Can the system be implemented within schedule and budget using current technology? And Can the system be integrated with other systems that are used?

5. Computer Science & Engineering – 20CS44P Requirements elicitation and analysis

6. Computer Science & Engineering – 20CS44P Requirements discovery This is the process of interacting with stakeholders of the system to discover their requirements Domain requirements from stakeholders and documentation are also discovered during this activity

7. Computer Science & Engineering – 20CS44P Requirements classification and organization This activity takes the unstructured collection of requirements, groups related requirements, and organizes them into coherent clusters The most common way of grouping requirements is to use a model of the system architecture to identify sub-systems and to associate requirements with each sub-system

8. Computer Science & Engineering – 20CS44P Requirements prioritization and negotiation Inevitably, when multiple stakeholders are involved, requirements will conflict. This activity is concerned with prioritizing requirements and finding and resolving requirements conflicts through negotiation. Usually, stakeholders have to meet to resolve differences and agree on compromise requirements.

9. Computer Science & Engineering – 20CS44P Requirements specification The requirements are documented and input into the next round of the spiral. Formal or informal requirements documents may be produced.

10. Computer Science & Engineering – 20CS44P Requirements specification Software requirement specification is a kind of document which is created by a software analyst after the requirements collected from the various sources - the requirement received by the customer written in ordinary language. It is the job of the analyst to write the requirement in technical language so that they can be understood and beneficial by the development team.

11. Computer Science & Engineering – 20CS44P The models used at this stage include ER diagrams, data flow diagrams (DFDs), function decomposition diagrams (FDDs), data dictionaries, etc. Data flow diagrams (DFDs) : They are used widely for modelling the requirements. DFD shows the flow of data through a system Data Dictionaries: Data Dictionaries are simply repositories to store information about all data items defined in DFDs

12. Computer Science & Engineering – 20CS44P Entity-Relationship Diagrams: Another tool for requirement specification is the entity-relationship diagram, often called an "E-R diagram." It is a detailed logical representation of the data for the organization and uses three main constructs i.e. data entities, relationships, and their associated attributes.

13. Computer Science & Engineering – 20CS44P Requirements validation Requirements validation is the process of checking that requirements actually define the system that the customer really wants. It overlaps with analysis as it is concerned with finding problems with the requirements. Requirements validation is important because errors in a requirements document can lead to extensive rework costs when these problems are discovered during development or after the system is in service.

14. Computer Science & Engineering – 20CS44P During the requirements validation process, different types of checks should be carried out on the requirements in the requirements document. These checks include: Validity checks A user may think that a system is needed to perform certain functions. Consistency checks Requirements in the document should not conflict.

15. Computer Science & Engineering – 20CS44P Completeness checks The requirements document should include requirements that define all functions and the constraints intended by the system user. Realism checks Using knowledge of existing technology, the requirements should be checked to ensure that they can actually be implemented. Verifiability To reduce the potential for dispute between customer and contractor, system requirements should always be written so that they are verifiable.

16. Computer Science & Engineering – 20CS44P Typical Requirements Engineering Problems Understanding large and complex system requirements is difficult Undefined system boundaries Customers/Stakeholders are not clear about their needs Conflicting requirements are there Changing requirements is another issue Partitioning the system suitably to reduce complexity

17. Computer Science & Engineering – 20CS44P Validating and Tracing requirements Identifying critical requirements Resolving the “to be determined” part of the requirements Proper documentation, proper meeting time, and budget constraints

18. Thank you Computer Science & Engineering – 20CS44P Chairperson: Smt. Usha D 136-Government Polytechnic, Bagepalli Moderator : Smt. Sunandadevi V K 109-136-Government Polytechnic, Kalaburagi Subject Rewiever Smt. Suvarna Mahadev V M 136-Government Polytechnic, Bagepalli Content Developers 1. LOHITH S Y 173-gpt, Harapanahalli 2. Raghavendra M 131 School of Mines KGF 3.Poornima Kebbepura R C 112, Gpt, Tumkur 4. O K MANJUNATHA 156 GPT MULBAGAL 5. JYOTHI B.K 177 GPT SIDDAPUR. 6. PALLAVI H S 169 GPT KGF 7. A V RADHIKA 149, GPT ,CHITRADURGA