1. Coming up: What is a requirement? 1 Software Engineering: A Practitioner’s Approach, 6/e Chapter 7 Requirements Engineering Modified to include some Agile Concepts Software Engineering: A Practitioner’s Approach, 6/e Chapter 7 Requirements Engineering Modified to include some Agile Concepts copyright © 1996, 2001, 2005 R.S. Pressman & Associates, Inc. NOTE: Some slides referenced from: Ian Sommerville Slides for Software Engineering.

2. Coming up: Requirements come in many forms 2 What is a requirement? Requirements are used to describe all aspects of a system Requirements are used to describe all aspects of a system They may range from a high-level abstract statement of a service or of a system constraint to a detailed mathematical functional specification They may range from a high-level abstract statement of a service or of a system constraint to a detailed mathematical functional specification They serve many roles They serve many roles May be the basis for a bid for a contract - therefore must be open to interpretation May be the basis for a bid for a contract - therefore must be open to interpretation May be the basis for the contract itself - therefore must be defined in detail May be the basis for the contract itself - therefore must be defined in detail Are always used to communicate what you intend to build Are always used to communicate what you intend to build

3. Requirements come in many forms Requirements Statements – ex: “The system shall ….” Requirements Statements – ex: “The system shall ….” UML Use-case diagrams UML Use-case diagrams eXtreme Programming “User Stories” eXtreme Programming “User Stories” Scrum Product Backlog Scrum Product Backlog Any other documents that communicate what you intend to build Any other documents that communicate what you intend to build Prototypes can be used as requirements Prototypes can be used as requirements Existing systems can serve as requirements “Build this system, but use Java instead of Fortran” Existing systems can serve as requirements “Build this system, but use Java instead of Fortran” UML Sequence diagrams, State charts, activity diagrams… UML Sequence diagrams, State charts, activity diagrams… 3 Coming up: All Requirements

4. Coming up: Typical Requirements Statements 4 All Requirements Should specify external behavior of the system Should specify external behavior of the system Includes functional and non-functional requirements Includes functional and non-functional requirements Functional requirements are statements of the services that the system must provide Functional requirements are statements of the services that the system must provide What must the system do? (Start with the phrase “The system shall…”) What must the system do? (Start with the phrase “The system shall…”) Non-functional requirements are constraints on the services and functions offered by the system Non-functional requirements are constraints on the services and functions offered by the system How must it do it? or a constraint on the system How must it do it? or a constraint on the system

5. Coming up: Why do we care? 5 Typical Requirements Statements Functional: The system shall display the heart rate, blood pressure and temperature of a patient connected to the patient monitor. Functional: The system shall display the heart rate, blood pressure and temperature of a patient connected to the patient monitor. Non-Functional: "Display of the patient's vital signs must respond to a change in the patient's status within 2 seconds.” Non-Functional: "Display of the patient's vital signs must respond to a change in the patient's status within 2 seconds.” ‘ilities’ - Performance, Scalability, Capacity, Availability Reliability, Recoverability, Maintainability, Serviceability, Security, Regulatory,Manageability ‘ilities’ - Performance, Scalability, Capacity, Availability Reliability, Recoverability, Maintainability, Serviceability, Security, Regulatory,Manageability What are some functional requirements on an iPod? Non-functional?

6. Coming up: Prescriptive versus Agile approach 6 Why do we care? Most large software systems address wicked problems Most large software systems address wicked problems Problems which are so complex that they can never be fully understood and where understanding develops during the system development Problems which are so complex that they can never be fully understood and where understanding develops during the system development Therefore, requirements are normally both incomplete and inconsistent Therefore, requirements are normally both incomplete and inconsistent Requirements help by giving you the best understanding you can have at the beginning Requirements help by giving you the best understanding you can have at the beginning I’ll destroy you and your little software project to! problem

7. Prescriptive versus Agile approach Prescriptive – approach is to minimize/prevent change by understanding system thoroughly at the beginning Prescriptive – approach is to minimize/prevent change by understanding system thoroughly at the beginning Typically heard: “A change during implementation costs 10 times more than a change during requirements phase” Typically heard: “A change during implementation costs 10 times more than a change during requirements phase” Agile – approach is to manage change by being flexible (i.e. Agile) Agile – approach is to manage change by being flexible (i.e. Agile) Typically heard: Requirements planned for 6 months from now are most likely completely inaccurate. Don’t waste resources planning far ahead. Plan short iterations and adjust the plan as you go. Typically heard: Requirements planned for 6 months from now are most likely completely inaccurate. Don’t waste resources planning far ahead. Plan short iterations and adjust the plan as you go. 7 Coming up: Typical Prescriptive Requirements Engineering Process

8. Coming up: Requirements Engineering-II 8 Typical Prescriptive Requirements Engineering Process Inception—ask a set of questions that establish … Inception—ask a set of questions that establish … basic understanding of the problem basic understanding of the problem the people who want a solution the people who want a solution the nature of the solution that is desired, and the nature of the solution that is desired, and the effectiveness of preliminary communication and collaboration between the customer and the developer the effectiveness of preliminary communication and collaboration between the customer and the developer Elicitation—elicit requirements from all stakeholders Elicitation—elicit requirements from all stakeholders to identify the problem to identify the problem propose elements of the solution propose elements of the solution negotiate different approaches, and negotiate different approaches, and specify a preliminary set of solution requirements specify a preliminary set of solution requirements Elaboration—create an analysis model that identifies data, function and behavioral requirements Elaboration—create an analysis model that identifies data, function and behavioral requirements Negotiation—agree on a deliverable system that is realistic for developers and customers Negotiation—agree on a deliverable system that is realistic for developers and customers

9. Coming up: Typical Prescriptive Requirements Document Structure 9 Requirements Engineering-II Specification—can be any one (or more) of the following: Specification—can be any one (or more) of the following: A written document A written document A set of models A set of models A formal mathematical A formal mathematical A collection of user scenarios (use-cases) A collection of user scenarios (use-cases) A prototype A prototype Validation—a review mechanism that looks for Validation—a review mechanism that looks for errors in content or interpretation errors in content or interpretation areas where clarification may be required areas where clarification may be required missing information missing information inconsistencies (a major problem when large products or systems are engineered) inconsistencies (a major problem when large products or systems are engineered) conflicting or unrealistic (unachievable) requirements. conflicting or unrealistic (unachievable) requirements. Requirements management Requirements management

10. Coming up: Inception 10 Typical Prescriptive Requirements Document Structure Purpose Purpose Overall Description Overall Description System Features (Functional Requirements/Use Cases) System Features (Functional Requirements/Use Cases) External Interface Requirements External Interface Requirements User interface requirements or standards User interface requirements or standards Hardware interfaces to other systems Hardware interfaces to other systems Software interfaces to other systems Software interfaces to other systems Communication Interfaces Communication Interfaces Non-functional Requirements Non-functional Requirements Appendices - analysis model diagrams Appendices - analysis model diagrams See SRS Template on CS421 Project Page (provided by http://www.processimpact.com/ … but essentially from IEEE). See SRS Template on CS421 Project Page (provided by http://www.processimpact.com/ … but essentially from IEEE).http://www.processimpact.com/

11. Coming up: Eliciting Requirements 11 Inception Identify stakeholders Identify stakeholders “who else do you think I should talk to?” “who else do you think I should talk to?” Recognize multiple points of view Recognize multiple points of view Work toward collaboration Work toward collaboration The first questions The first questions Who is behind the request for this work? Who is behind the request for this work? Who will use the solution? Who will use the solution? What will be the economic benefit of a successful solution What will be the economic benefit of a successful solution Is there another source for the solution that you need? Is there another source for the solution that you need?

12. Coming up: Eliciting Requirements 12 Eliciting Requirements meetings are conducted and attended by both software engineers and customers meetings are conducted and attended by both software engineers and customers rules for preparation and participation are established rules for preparation and participation are established an agenda is suggested an agenda is suggested a "facilitator" (can be a customer, a developer, or an outsider) controls the meeting a "facilitator" (can be a customer, a developer, or an outsider) controls the meeting a "definition mechanism" (can be work sheets, flip charts, or wall stickers or an electronic bulletin board, chat room or virtual forum) is used a "definition mechanism" (can be work sheets, flip charts, or wall stickers or an electronic bulletin board, chat room or virtual forum) is used the goal is the goal is to identify the problem to identify the problem propose elements of the solution propose elements of the solution negotiate different approaches, and negotiate different approaches, and specify a preliminary set of solution requirements specify a preliminary set of solution requirements

13. Coming up: Elicitation Work Products 13 Eliciting Requirements

14. Coming up: Analysis Model 14 Elicitation Work Products a statement of need and feasibility. a statement of need and feasibility. a bounded statement of scope for the system or product. a bounded statement of scope for the system or product. a list of customers, users, and other stakeholders who participated in requirements elicitation a list of customers, users, and other stakeholders who participated in requirements elicitation a description of the system’s technical environment. a description of the system’s technical environment. a list of requirements (preferably organized by function) and the domain constraints that apply to each. a list of requirements (preferably organized by function) and the domain constraints that apply to each. a set of usage scenarios that provide insight into the use of the system or product under different operating conditions. a set of usage scenarios that provide insight into the use of the system or product under different operating conditions. any prototypesdeveloped to better define requirements any prototypes developed to better define requirements.

15. Coming up: Use-Cases 15 Analysis Model Included to provide more clarification about textual requirements (where needed) Included to provide more clarification about textual requirements (where needed) Elements of the analysis model Elements of the analysis model Scenario-based elements Scenario-based elements Functional—processing narratives for software functions Functional—processing narratives for software functions Use-case—descriptions of the interaction between an “actor” and the system Use-case—descriptions of the interaction between an “actor” and the system Class-based elements – e.g. class diagram Class-based elements – e.g. class diagram Behavioral elements – e.g. state diagram, sequence diagram, activity diagram, etc.. Behavioral elements – e.g. state diagram, sequence diagram, activity diagram, etc.. Flow-oriented elements – e.g. data flow diagram Flow-oriented elements – e.g. data flow diagram

16. Coming up: Use-Case Diagram 16Use-Cases A collection of user scenarios that describe the thread of usage of a system A collection of user scenarios that describe the thread of usage of a system Each scenario is described from the point-of-view of an “actor”—a person or device that interacts with the software in some way Each scenario is described from the point-of-view of an “actor”—a person or device that interacts with the software in some way Each scenario answers the following questions: Each scenario answers the following questions: Who is the primary actor, the secondary actor (s)? Who is the primary actor, the secondary actor (s)? What are the actor’s goals? What are the actor’s goals? What preconditions should exist before the story begins? What preconditions should exist before the story begins? What main tasks or functions are performed by the actor? What main tasks or functions are performed by the actor? What extensions might be considered as the story is described? What extensions might be considered as the story is described? What variations in the actor’s interaction are possible? What variations in the actor’s interaction are possible? What system information will the actor acquire, produce, or change? What system information will the actor acquire, produce, or change? Will the actor have to inform the system about changes in the external environment? Will the actor have to inform the system about changes in the external environment? What information does the actor desire from the system? What information does the actor desire from the system? Does the actor wish to be informed about unexpected changes? Does the actor wish to be informed about unexpected changes?

17. Coming up: Use Case Description 17 Use-Case Diagram Each oval is a separate use case that has a description Each stick figure is an actor in your system The block is an external system that interacts with your system. Any system you aren’t developing is external

18. Use Case Description ID - ID - A unique to reference this use case U01, U02, etc…) Objective - What is the ultimate objective of the use-case. What is it trying to achieve? What was the source of the use-case requirement? Objective - What is the ultimate objective of the use-case. What is it trying to achieve? What was the source of the use-case requirement? Priority – The overall priority of this use-case (Low, Medium, High) Priority – The overall priority of this use-case (Low, Medium, High) Source – Who is the main source of this use case. Who cares most about this functionality? This should be the one person you would ask if there is a question about this use-case. (Make up a name and cite their: John Smith (End-user) here.) Source – Who is the main source of this use case. Who cares most about this functionality? This should be the one person you would ask if there is a question about this use-case. (Make up a name and cite their: John Smith (End-user) here.) Actors - Who is involved in the use-case? Which actors/stakeholders? Actors - Who is involved in the use-case? Which actors/stakeholders? Flow of Events Flow of Events Basic Flow - flow of events normally executed in the use-case Basic Flow - flow of events normally executed in the use-case Alternative Flow(s) - a secondary flow of events due to infrequent conditions Alternative Flow(s) - a secondary flow of events due to infrequent conditions Exception Flow(s) - Exceptions that may happen during the execution of the use case Exception Flow(s) - Exceptions that may happen during the execution of the use case Includes - other use case IDs that are referenced in steps in the flow of events. Includes - other use case IDs that are referenced in steps in the flow of events. Preconditions - Any condition that must be satisfied before the use case begins. If the condition is “User is logged in”, then the first step of the use case is NOT “User logs in”. They are already logged in if that is a pre- condition! Preconditions - Any condition that must be satisfied before the use case begins. If the condition is “User is logged in”, then the first step of the use case is NOT “User logs in”. They are already logged in if that is a pre- condition! Post conditions - The conditions that will be satisfied after the use case successfully completes (typically same as objective) Post conditions - The conditions that will be satisfied after the use case successfully completes (typically same as objective) Notes/Issues - Any relevant notes or issues that need to be resolved Notes/Issues - Any relevant notes or issues that need to be resolved 18 Coming up: eXtreme Programming (XP): User Stories

19. eXtreme Programming (XP): User Stories Serve as requirements within the XP process Serve as requirements within the XP process Written by customers Written by customers Time Estimated by developers Time Estimated by developers Replaces large requirements documents Replaces large requirements documents Represents anything that is “progress” to the customer Represents anything that is “progress” to the customer Examples: Examples: Students can purchase monthly parking passes online. Students can purchase monthly parking passes online. Parking passes can be paid via credit cards. Parking passes can be paid via credit cards. Parking passes can be paid via PayPal Parking passes can be paid via PayPal Professors can input student marks. Professors can input student marks. Students can obtain their current seminar schedule. ･ Students can order official transcripts. Students can obtain their current seminar schedule. ･ Students can order official transcripts. 19 Coming up: eXtreme Programming (XP): User Stories

20. eXtreme Programming (XP): User Stories Short – 1 or 2 sentences. Usually supposed to fit on a 3x5 notecard Short – 1 or 2 sentences. Usually supposed to fit on a 3x5 notecard Easy to estimate (project velocity) Easy to estimate (project velocity) Allows requirements to change frequently with less impact Allows requirements to change frequently with less impact Without accompanying validation tests may lead to misinterpretation Without accompanying validation tests may lead to misinterpretation Difficult to scale to very large projects Difficult to scale to very large projects Require close customer contact to ensure correct implementation Require close customer contact to ensure correct implementation 20 Coming up: Format for User Stories (CS421 only… not standard!)

21. Format for User Stories (CS421 only… not standard!) Unique Identifier Unique Identifier Source – who should developer contact with questions about this? Source – who should developer contact with questions about this? Story – short (1-3 sentence) high-level description of story. When the developer plans to implement they should discuss with the customer the details. Story – short (1-3 sentence) high-level description of story. When the developer plans to implement they should discuss with the customer the details. As a [user role], I want to [goal], so I can [reason]. As a [user role], I want to [goal], so I can [reason]. Time estimate – how long in “ideal development time” – time without meetings or any interruptions Time estimate – how long in “ideal development time” – time without meetings or any interruptions Client’s Priority – how important is the story to the client? (Low, Medium, High) Client’s Priority – how important is the story to the client? (Low, Medium, High) Coming up: The web has MANY references about User Stories and Use Cases. 21

22. The web has MANY references about User Stories and Use Cases. User Stories: http://www.agile-software- development.com/search/label/user%20stories User Stories: http://www.agile-software- development.com/search/label/user%20stories Use Cases: http://alistair.cockburn.us/Use+case+fundamentals Use Cases: http://alistair.cockburn.us/Use+case+fundamentals Which is better? Many arguments – here is one: http://alistair.cockburn.us/Why+I+still+use+use+cases Which is better? Many arguments – here is one: http://alistair.cockburn.us/Why+I+still+use+use+cases Coming up: Agile and Traditional Requirements share more than they differ 22

23. Agile and Traditional Requirements share more than they differ Coming up: Negotiating Requirements 23

24. Coming up: Reasons we need to negotiate 24 Negotiating Requirements Identify the key stakeholders Identify the key stakeholders These are the people who will be involved in the negotiation These are the people who will be involved in the negotiation Determine each of the stakeholders’ “win conditions” Determine each of the stakeholders’ “win conditions” Win conditions are not always obvious Win conditions are not always obvious Negotiate Negotiate Work toward a set of requirements that lead to “win-win” Work toward a set of requirements that lead to “win-win”

25. Coming up: Requirements Rationale 25 Reasons we need to negotiate Discuss Large software systems must improve the current situation. It is hard to anticipate the effects that the new system will have on the organization Discuss Large software systems must improve the current situation. It is hard to anticipate the effects that the new system will have on the organization Discuss Prototyping is often required to clarify requirements Discuss Prototyping is often required to clarify requirements Negotiate Different users have different requirements and priorities. There is a constantly shifting compromise in the requirements Negotiate Different users have different requirements and priorities. There is a constantly shifting compromise in the requirements Negotiate System end-users and organizations who pay for the system have different requirements Negotiate System end-users and organizations who pay for the system have different requirements

26. Coming up: Non-Functional Requirement Types 26 Requirements Rationale It is important to provide rationale with requirements It is important to provide rationale with requirements This helps the developer understand the application domain and why the requirement is stated in its current form This helps the developer understand the application domain and why the requirement is stated in its current form Particularly important when requirements have to be changed. The availability of rationale reduces the chances that change will have unexpected effects Particularly important when requirements have to be changed. The availability of rationale reduces the chances that change will have unexpected effects In this class we’ll provide the requirement’s source and assume they can contact the source to get a rationale if needed instead of an explicit “rationale” In this class we’ll provide the requirement’s source and assume they can contact the source to get a rationale if needed instead of an explicit “rationale”

27. Coming up: Non-Functional Requirement Examples 27 Non-Functional Requirement Types Product requirements Product requirements Requirements which specify that the delivered product must behave in a particular way e.g. execution speed, reliability, etc. Requirements which specify that the delivered product must behave in a particular way e.g. execution speed, reliability, etc. Organizational requirements Organizational requirements Requirements which are a consequence of organizational policies and procedures e.g. process standards used, implementation requirements, etc. Requirements which are a consequence of organizational policies and procedures e.g. process standards used, implementation requirements, etc. External requirements External requirements Requirements which arise from factors which are external to the system and its development process e.g. interoperability requirements, legislative requirements, etc. Requirements which arise from factors which are external to the system and its development process e.g. interoperability requirements, legislative requirements, etc. Remember: Non Functional = How the system should do something

28. Coming up: Requirements must be testable 28 Non-Functional Requirement Examples Product requirement Product requirement 4.C.8 It shall be possible for all necessary communication between the APSE and the user to be expressed in the standard Ada character set. 4.C.8 It shall be possible for all necessary communication between the APSE and the user to be expressed in the standard Ada character set. Organizational requirement Organizational requirement 9.3.2 The system development process and deliverable documents shall conform to the process and deliverables defined in XYZCo-SP- STAN-95. 9.3.2 The system development process and deliverable documents shall conform to the process and deliverables defined in XYZCo-SP- STAN-95. External requirement External requirement 7.6.5 The system shall provide facilities that allow any user to check if personal data is maintained on the system. A procedure must be defined and supported in the software that will allow users to inspect personal data and to correct any errors in that data. 7.6.5 The system shall provide facilities that allow any user to check if personal data is maintained on the system. A procedure must be defined and supported in the software that will allow users to inspect personal data and to correct any errors in that data. security, maintainability constraint: quality constraint: interoperability Agile stories? How?

29. Coming up: Requirements: testable metrics 29 Requirements must be testable Traditional requirements must be written so that they can be objectively verified. Traditional requirements must be written so that they can be objectively verified. XP requirements have explicit acceptance test cases written by the customers to solve this problem. XP requirements have explicit acceptance test cases written by the customers to solve this problem. The problem with this requirement is its use of vague terms such as ‘errors shall be minimized” The problem with this requirement is its use of vague terms such as ‘errors shall be minimized” The system should be easy to use by experienced controllers and should be organized in such a way that user errors are minimized. The system should be easy to use by experienced controllers and should be organized in such a way that user errors are minimized. The error rate should be been quantified The error rate should be been quantified Experienced controllers should be able to use all the system functions after a total of two hours training. After this training, the average number of errors made by experienced users should not exceed two per day. Experienced controllers should be able to use all the system functions after a total of two hours training. After this training, the average number of errors made by experienced users should not exceed two per day.

30. Coming up: System Level Requirements 30 Requirements: testable metrics

31. Coming up: Requirements Validation 31 System Level Requirements Some requirements place constraints on the system as a whole rather than specific system functions Some requirements place constraints on the system as a whole rather than specific system functions Example Example The time required for training a system operator to be proficient in the use of the system must not exceed 2 working days. The time required for training a system operator to be proficient in the use of the system must not exceed 2 working days. These may be emergent requirements which cannot be derived from any single sub-set of the system requirements These may be emergent requirements which cannot be derived from any single sub-set of the system requirements

32. Coming up: Validating Requirements-I 32 Requirements Validation Concerned with demonstrating that the requirements define the system that the customer really wants Concerned with demonstrating that the requirements define the system that the customer really wants Requirements error costs are high so validation is very important Requirements error costs are high so validation is very important Fixing a requirements error after delivery may cost up to 100 times the cost of fixing an implementation error Fixing a requirements error after delivery may cost up to 100 times the cost of fixing an implementation error Prototyping is an important technique of requirements validation Prototyping is an important technique of requirements validation

33. Coming up: Validating Requirements-II 33 Validating Requirements-I Is each requirement consistent with the overall objective for the system/product? Work with all parties on this question! Is each requirement consistent with the overall objective for the system/product? Work with all parties on this question! Have all requirements been specified at the proper level of abstraction? That is, do some requirements provide a level of technical detail that is inappropriate at this stage? Have all requirements been specified at the proper level of abstraction? That is, do some requirements provide a level of technical detail that is inappropriate at this stage? Is the requirement really necessary or does it represent an add-on feature that may not be essential to the objective of the system? Is the requirement really necessary or does it represent an add-on feature that may not be essential to the objective of the system? Is each requirement bounded and unambiguous? Is each requirement bounded and unambiguous? Does each requirement have attribution? That is, is a source (generally, a specific individual) noted for each requirement? Does each requirement have attribution? That is, is a source (generally, a specific individual) noted for each requirement? Do any requirements conflict with other requirements? Do any requirements conflict with other requirements?

34. Coming up: Requirements Reviews 34 Validating Requirements-II Is each requirement achievable in the technical environment that will house the system or product? Is each requirement achievable in the technical environment that will house the system or product? Is each requirement testable, once implemented? Is each requirement testable, once implemented? Does the requirements model properly reflect the information, function and behavior of the system to be built. Does the requirements model properly reflect the information, function and behavior of the system to be built. Has the requirements model been “partitioned” in a way that exposes progressively more detailed information about the system. Has the requirements model been “partitioned” in a way that exposes progressively more detailed information about the system. Have requirements patterns been used to simplify the requirements model. Have all patterns been properly validated? Are all patterns consistent with customer requirements? Have requirements patterns been used to simplify the requirements model. Have all patterns been properly validated? Are all patterns consistent with customer requirements?

35. Coming up: Requirements Reviews Check 35 Requirements Reviews Regular reviews should be held while the requirements definition is being formulated Regular reviews should be held while the requirements definition is being formulated Both client and contractor staff should be involved in reviews Both client and contractor staff should be involved in reviews Reviews may be formal (with completed documents) or informal. Good communications between developers, customers and users can resolve problems at an early stage Reviews may be formal (with completed documents) or informal. Good communications between developers, customers and users can resolve problems at an early stage

36. Coming up: Requirements final thoughts… 36 Requirements Reviews Check Verifiability. Is the requirement realistically testable? Verifiability. Is the requirement realistically testable? Comprehensibility. Is the requirement properly understood? Comprehensibility. Is the requirement properly understood? Traceability. Is the origin of the requirement clearly stated? Traceability. Is the origin of the requirement clearly stated? Adaptability. Can the requirement be changed without a large impact on other requirements? Adaptability. Can the requirement be changed without a large impact on other requirements?

37. Coming up: Requirements final thoughts… 37 Requirements final thoughts… Requirements should specify one and only one thing Requirements should specify one and only one thing Requirements and User Stories can only pass or fail, they can’t partially pass. If you want to partially pass a requirement split into two Requirements and User Stories can only pass or fail, they can’t partially pass. If you want to partially pass a requirement split into two Requirements must be testable Requirements must be testable Requirements must specify what YOUR system must do, not what other (external) systems do Requirements must specify what YOUR system must do, not what other (external) systems do To make this easier, in this class all functional requirements must begin with “The system shall…” To make this easier, in this class all functional requirements must begin with “The system shall…” Must have a source (make it up for CS421) Must have a source (make it up for CS421)

38. Coming up: Requirements must have a unique ID 38 Requirements final thoughts… Should not be a design choice (this is hard to get right). Should not be a design choice (this is hard to get right). The system shall store user information including name, DOB, address and SSN. <-- Good! The system shall store user information including name, DOB, address and SSN. <-- Good! The system shall store user information in an Oracle database including name, DOB, address, SSN. <-- bad The system shall store user information in an Oracle database including name, DOB, address, SSN. <-- bad Is Oracle really REQUIRED? Hard to say… maybe, but probably not. This is a decision you would make at implementation design time. Is Oracle really REQUIRED? Hard to say… maybe, but probably not. This is a decision you would make at implementation design time. Question: Does the customer care that you use Oracle? MySQL? Etc.. Maybe someone found some other MUCH BETTER approach storing the data on moon rocks. Question: Does the customer care that you use Oracle? MySQL? Etc.. Maybe someone found some other MUCH BETTER approach storing the data on moon rocks. Again: This is hard to avoid… and I’m not to concerned with it on the SRS, but I want you to be very aware of when you are making design choices instead of required features. Again: This is hard to avoid… and I’m not to concerned with it on the SRS, but I want you to be very aware of when you are making design choices instead of required features.

39. Coming up: Bad Example Requirements Statements 39 Requirements must have a unique ID Must have a unique ID. Must have a unique ID. When testing you need to reference REQ-1 or REQ-287. Multiple things cannot be labeled REQ-1. When testing you need to reference REQ-1 or REQ-287. Multiple things cannot be labeled REQ-1. Later our test cases will say: This test case validates requirements REQ-1, REQ-27, and REQ-56. Later our test cases will say: This test case validates requirements REQ-1, REQ-27, and REQ-56.

40. Coming up: Bad Examples 40 Bad Example Requirements Statements Bad requirements examples: The system shall validate and accept credit cards and cashier’s checks. High priority. The system shall validate and accept credit cards and cashier’s checks. High priority. The system shall process all mouse clicks very fast to ensure user’s do not have to wait. The system shall process all mouse clicks very fast to ensure user’s do not have to wait. The user must have Adobe Acrobat installed. The user must have Adobe Acrobat installed. These don’t have a source or unique ID, but what else is wrong?

41. Coming up: The Result of Good Requirements 41 Bad Examples The system shall validate and accept credit cards and cashier’s checks. High priority. The system shall validate and accept credit cards and cashier’s checks. High priority. Problem: two requirements instead of one. Problem: two requirements instead of one. If the credit card processing works, but the cashier’s check validation does not… is this requirement pass or fail? Has to be fail, but that is misleading. If the credit card processing works, but the cashier’s check validation does not… is this requirement pass or fail? Has to be fail, but that is misleading. Maybe only credit cards are high priority and cashier’s checks are low priority. Maybe only credit cards are high priority and cashier’s checks are low priority. The system shall process all mouse clicks very fast to ensure user’s do not have to wait. The system shall process all mouse clicks very fast to ensure user’s do not have to wait. Problem: This is not testable. Quantify how fast is acceptable? Problem: This is not testable. Quantify how fast is acceptable? The user must have Adobe Acrobat installed. The user must have Adobe Acrobat installed. Problem: This is not something our system must do. It could be in the constraints/assumptions or maybe operating environment sections, but is not a functional requirement of our system Problem: This is not something our system must do. It could be in the constraints/assumptions or maybe operating environment sections, but is not a functional requirement of our system

42. End of presentation 42 The Result of Good Requirements I’m melting! Your wicked problems melt into small manageable problems ….