1. CS 641 – Requirements Engineering Chapters 7-9

2. Agenda Fit Criterion Functional Requirements Non-functional Requirements

3. Fit Criteria Definition “If there is a requirement for the product to carry out some function, then the testing activity must demonstrate that the product indeed performs that function or have that property.” criterion to compare against Therefore, the requirement must have a benchmark or fit criterion to compare against. is the fit criterion The measurement of the requirement is the fit criterion. It quantifies the behavior, the performance, or some other quality of the requirement.

4. Why Does Fit Need a Criterion? the builders will naturally build a product to meet that criterion. If they know the performance criterion the product must meet before it is accepted, the builders will naturally build a product to meet that criterion.

5. Scale of Measurement The unit that is used to test achievement Examples:  Speed of operation – microseconds, minutes  Usability – time needed to learn product, time taken to achieve an agreed level of competence, error rate of work done  Component Color - % of various colors  Sound – loudness/softness measured in volume

6. Chapter 7 – Functional Requirements Specifications of the products functionality Actions the product must take:  Check  Calculate  Record  Retrieve Derived from the fundamental purpose of the product Functional requirements Functional requirements describe what the product has to do to satisfy the work or business, and are independent of any technology used by the product. Not a quality

7. How to Find Them The business context is broken into business events. Business events determine the product’s use cases. For each use case we build a scenario Each of the steps in the scenario is a task that the actor describes. The tasks or steps are described in the actor’s language, so it may be general or at a high-level to describe the details of the product’s capabilities. These steps provide a vehicle for determining all of the functional requirements that are needed by each step. These steps provide a vehicle for determining all of the functional requirements that are needed by each step.

8. Use Case Steps for Discovering Functional Requirements Functional Requirement Use Case Step Functional Requirement Functional Requirement Step Functional Requirement Functional Requirement Functional Requirement Functional Requirement Functional Requirement

9. Example This use case diagram shows the product producing the road deicing schedule. It is triggered by the Truck Depot Supervisor. The Thermal Mapping Database is a cooperative adjacent system providing information to the use case upon request.

10. Example – Cont. Let's see how this process works by using an example of the "Produce Road De-icing Schedule.“ use case scenario Product use case: Produce road de-icing scheduleSteps:  Engineer provides a scheduling date and district identifier.  Product selects the relevant thermal maps.  Product uses the thermal maps, district temperature readings, and weather forecasts to predict temperatures for each road section for the district.  Product predicts which roads will freeze and when they will freeze.  Product schedules available trucks from the relevant depots.  Product advises the engineer of the schedule.

11. Example – Cont.  For each one asks, "What does the product have to do to complete this step?"  For example, the first step in the scenario is 1) Engineer provides a scheduling date and district identifier. The first functional requirement to come from this step is fairly obvious:  The product shall accept a scheduling date. Another requirement from the first step is  The product shall accept a valid district identifier.

12. Requirements, Not Solutions There is a difference between a requirement and its solution. It is important to your requirements discovery that you do not write solutions instead of requirements. Example:  “The product shall display pictures of goods for the customer to click on.” The requirements analyst has assumed a screen, a picture, and ordering by clicking. Here's the correct way to write this requirement:  “The product shall enable the customer to select the goods he wishes to order.”

13. Fit Criteria for Functional Requirements For functional requirements, there are no scales of measurement. The action is either completed or not. The resulting action has resulted in correct handling of the data.

14. Functional Requirement Fit Criteria: Example Description: Description: The product shall record the weather station readings. Fit criterion: Fit criterion: The recorded weather station readings shall match the readings sent by the weather station.

15. Chapter 8 – Non-functional Requirements

16. Non-functional Requirements They do not alter the products essential functionality. Discovered during trawling & prototyping. Are qualities that the functionality must have. It can represent the use case as a whole or one of the specific functional requirements

17. Use Case Non-functional Requirement Representation Look & Feel Performance Maintainability Operation Legal Security Political Usability Product Use Case Functional Requirement Functional Requirement Functional Requirement

18. Types of Non-functional Requirements 10. Look and Feel Requirements 10. Look and Feel Requirements – the spirit of the product’s appearance 11. Usability Requirements 11. Usability Requirements – the product’s ease of use, and special usability considerations 12. Performance Requirements 12. Performance Requirements – how fast, how safe, how many, how accurate the functionality must be 13. Operational Requirements 13. Operational Requirements – the operating environment of the product, and what considerations must be made for that environment 14. Maintainability and Portability Requirements 14. Maintainability and Portability Requirements – expected changes, and the time allowed to make them happen 15. Security Requirements 15. Security Requirements – the security and confidentiality of the product 16. Cultural and Political Requirements 16. Cultural and Political Requirements – special requirements that come about because of the people involved in the product’s development and operation 17. Legal Requirements 17. Legal Requirements – what laws and standards apply to the product

19. Non-functional Fit Criteria A fit criterion for non-functional requirements quantifies a particular quality that a product must have. These qualities include such things as: usability, look & feel, performance, security, etc.

20. Look & Feel Requirements – Type 10 - Examples Description: The product shall provide a graphic and colorful view of all the roads in the district. The product shall be attractive to a teenage audience. The product shall appear artistic. The product shall have an expensive appearance. The product shall conform to established look & fell of the organization’s requirements.

21. Non-functional Requirement Fit Criteria: Look & Feel Requirements Example Description : Description : The product shall conform to established look & fell of the organization’s requirements. Fit criterion: Fit criterion: The product shall conform to “company colors”. Fit criterion: Fit criterion: The product shall conform to interface guidelines as established in ….

22. Usability Requirements – Type 11 - Examples The product shall be easy to use. The product shall be easy to use by members of the public who may have only one free hand. The product shall be easy to use by graduate engineers. The product shall be easy to learn.

23. Non-functional Requirement Fit Criteria: Usability Requirements Example Description: Description: The product shall be user friendly. Fit criterion: Fit criterion: New users shall be able to add, change and delete roads within 30 minutes of their first attempt at using the product.

24. Non-functional Requirement Fit Criteria: Usability Requirements Example Description: The product shall be able to be used by a member of the public without training. Fit criterion: Fit criterion: Fit Criterion: 90% of a panel representative of the general public shall successfully purchase a ticket form the product on their first encounter.

25. Non-functional Requirement Fit Criteria: Usability Requirements Example Description: Description: The product shall be clear. Fit criterion: Fit criterion: Nine out of ten road engineers shall be able to successfully complete [list of selected tasks] after one day’s training.

26. Performance Requirements - Type 12 Aspects include:  Speed to complete a task  Accuracy of the results  Throughput such as the rate of transactions  Efficiency of resource usage  Reliability – usually expressed as mean time between failures  Availability – up time or time periods that users may access the product

27. Non-functional Requirement Fit Criteria: Performance Requirements Example Description: Description: The response shall be fast enough to avoid interrupting the user’s flow of thought. Fit criterion: Fit criterion: The response time shall be no more than 1.5 seconds for 95% of the responses, and no more than 4 seconds for the remainder.

28. Performance Requirements – Availability Example Description: Description: The product shall be available to users. Fit criterion: Fit criterion: In the first three months of operation, the product shall be available for 98% of the time between 8am and 8pm.

29. Non-functional Requirement Fit Criteria: Performance Requirements Example Description: Description: The product must produce the road de-icing schedule in an acceptable time. Fit criterion: Fit criterion: The road de-icing schedule shall be available to the engineer within 15 seconds for 90% of the times that it is produced. The remaining times it will be available within 20 seconds.

30. Operational Requirements - Type 13 Can Cover:  Operating environment  Condition of the users  Partner or collaborating systems  Portable products

31. Non-functional Requirement Fit Criteria: Operational Requirements Example Description: Description: The product shall be used in and around trucks. Description: Description: The product shall be operating at freezing temperatures. Description: Description: The product shall be operating at night. Description: Description: The product shall be operating when Lighting is poor. Description: Description: The product shall be operating when operator is wearing gloves. Fit criterion: Fit criterion: the operator shall successfully complete all tasks in a simulation of a 25-year storm (this is an accepted quantification of meteorological conditions) and the product shall function correctly after 24 hours exposure.

32. Maintainability Requirements - Type 14 Maintainability requirements specify the expectations about the maintenance of the product. The fit criteria for these requirements quantify the amount of time allowed to make certain changes The fit criteria for these requirements quantify the amount of time allowed to make certain changes

33. Maintainability Requirements - Type 14 - Examples Description: The product shall be readily portable to Linux. a future growth market.  Rationale: This has been identified as a future growth market. Description: The product shall be translated into various foreign languages. As yet, the languages are unknown.

34. Non-functional Requirement Fit Criteria: Maintainability Requirements Example Fit criterion: Fit criterion: New users shall be added to the system with no more than five minutes disruption to existing users. The fit criterion quantifies the amount of time, or effort, to satisfactorily port the software.

35. Security Requirements - Type 15 Security requirements cover the security of the product's operation. Description: Description: Only engineers using category A logons shall be able to alter the weather station data. Fit criterion: Fit criterion: Of 1000 alterations of the weather station data, none shall be from logons other than category A engineer logons.

36. Cultural & Political - Type 16 The main reason for cultural requirements comes when we try and sell a product into a different country, particularly when their culture and language is very different from our own. Examples:  All software shall be written in the United States.  The product shall not display religious symbols or words associated with mainstream religions.  The product shall use American spelling.

37. Cultural & Political Requirements - Fit Criteria Example Fit criterion: Fit criterion: The marketing department shall certify that all components are American made. Fit criterion: Fit criterion: Stan Hood of the auditing department shall approve the interface before it goes into production.

38. Legal Requirements - Type 17  Are there laws that are relevant to this product (privacy, data protection, guarantees, consumer credit, consumer protection, right to information, etc…) Fit criterion: Fit criterion: The legal department/company lawyers shall certify that the product complies with the [applicable laws.

39. Fit Criteria for Solution Constraints Section 4 of the Volere Requirements Specification Template contains constraints. We treat them as a special type of requirement that needs to be specified just like any other type of requirement. These constraints place restrictions on the way that the problem must be solved. For example: Description: Description: The software part of the product must run with the Linux system. Fit criterion: Fit criterion: The software part of the product shall comply with the specification of S.U.S.E. Linux release 5.2.

40. Finding the Nonfunctional Requirements - Example The IceBreaker product has a product use case called "Detect icy roads." This produces the road de-icing schedule showing the roads to be treated and the trucks allocated to them. The relevant stakeholders tell you that the schedule will be used by a junior or medium-grade engineer. For each of the nonfunctional requirements types, interview these stakeholders about the product's needs.

41. Finding the Nonfunctional Requirements - Example The Usability requirements  The product shall produce a schedule that is easy to read.  The product shall appear familiar to new engineers. The Maintainability requirements  The product shall enable the addition of new road authority areas within two days. The Performance requirements  The product shall produce the schedule within 3 seconds of the user's request.  The product shall be able to do ice prediction calculations for 5,000 roads.

42. Finding the Nonfunctional Requirements - Example The Security requirements  The product shall allow access only to junior and higher- grade engineers. The Legal requirements  The product shall produce an audit report of all road schedules and their subsequent treatments. This must comply with ISO 93.080.99. The Cultural and political requirements  The product shall be acceptable to the engineering community.

43. Quiz criterion) Give an example (along with Fit criterion) for the following Nonfunctional Requirements types:  The Usability Requirements  The Operational Requirements  The Security Requirements  The Legal Requirements

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