Why We Need Requirements If you do not know where you are going….you will wind up somewhere else!! Yogi Berra Most of us have learned this lesson and it is why we value requirements as a critical part of systems and software development 4 View slide
5 Requirements Definition and Management Business RealitiesTraditional methods yield excess rework, delays & poor quality
Late to marketby6 months or more will cost organizations 33% of the 5-year ROI
41% of projects fail to deliver expected business ROI
49% of projects overrun original estimates
70-80% of development costs are spent identifying and correcting defects
More than 40% of development budget will be consumed by poor requirements
200 50 20 Relative Cost to Repair 10 5 1-2 0 Acceptance QA Test Coding Design Analysis Maintenance
6 The purpose of requirements and requirement management Requirements and Requirement management need to do two things: 1) Validate - Make sure you are building the right product: Are we doing the right thing? 2) Verify - Make sure you built the product right: Are we doing the thing right?
7 What can happen when Requirements are not done right:
The Challenges of Developing Good Requirements
9 Executive Quality Manager We are continuously pushed to increase quality with less resources! Development and Test teams Poor Requirements Practices Pose Significant Challenges Across Teams We can’t keep up with requirement changes and know what is most important to develop and test We struggle with budgets and can’t consistently meet customer needs Reduce Cost Efficiency+Innovation Improve Quality Accelerate Delivery Time Analyst It’s hard to accurately capture requirements & make sure they are implemented & tested
10 Safety Regulatory compliance Development timescales Project scale Project life … Different industries have different needs… Cost Quality Time
11 Engineers like to solve problems Measure twice, cut once Look before you leap Thinking before you act saves time, money, effort and improves quality. It’s plain common sense, yet, when it comes to requirements management, this common sense seems not to be there. Many projects start before thought has been put into the project’s purpose, its desired results, and how its success will ultimately be measured.
12 Working with Requirements is a lifecycle activity You need to enable requirements to evolve during the lifecycle Increase the likelihood of delivering value early Minimizes risk Minimizes re-work Reduces confusion Improves quality
Requirements are always changing
Changes in environment (e.g. new threats) lead to changes in stakeholder needs
Changes in technology (e.g. cheaper memory) lead to new stakeholder requirements and possible solutions that are cheaper, faster, etc.
Changes in stakeholders (e.g. new customer in charge) lead new views and new stakeholder requirements
Changes in budget ( e.g. funding cut) funding lost
And the longer your development timescale the greater the chance that requirements will change during your project
14 Requirements come from everywhere Goal Feature Function Rule Regulation Risk Objective Need Aim Criterion Requirements
15 People over design Programs are getting so complex put solutions do not always need to be complicated. The simplest solution is usually the best. John Deere fuel tank sight gauge is a great example of this
16 There are many different types of requirements Stakeholder Requirements Architectural Requirements Structural Requirements Behavioral Requirements SystemsFunctional Requirements Non-functional Requirements Performance Requirements Design Requirements Derived Requirements Allocated Requirements ……….
17 Factors which complicate Requirements Management Multiple requirement sets Large number of requirements Different levels of requirements Version control Change control Product lines Distributed teams Different processes Impact of changes Systems of systems Convergence of old and new technologies
19 Requirement Writing
The art of writing requirements takes great skill and, like writing code, the end result is usually cleaner and more consistent if there’s a single author.
Don’t expect to get the requirements 100% correct. You need to allow for human nature and use the same language as your client.
The following guideline gives 13 tips on how to write better requirements by following simple rules for word selection and sentence structure.
Most of these guidelines only apply to the requirement statements, not the complete specification.
20 Requirement Writing 1: Use the simplest words appropriate to state a complete requirement. An eloquently written requirement is probably not a good one. A requirement must be written so many different people can understand it.
21 Requirement Writing 2: Use requirement imperatives correctly. Use company/program defined list. If requirements are from a non-company source, make sure you know the meaning of these words. (Definitions should be included in Section 1 of the specification) Common imperative definitions; “Shall” Definition “Shall” denotes a mandatory and contractual requirement. “Shall” requires metrics to quantify and requires a verification process. “Will” Definition “Will” denotes a mandatory and contractual requirement. It is similar to “shall” but does not require metrics or verification. “Should” Definition “Should” denote a design goal, an objective the system tries to meet.
22 Requirement Writing 3: Do not use weak phrases and subjective words. Following are words and phases not to use when writing a requirement: Adequate As Appropriate Bad Better But not limited to Correct Easy Effective Ideal Large Maximize Minimize Most Must Necessary Normal Quick Rapid Readily Relevant Satisfactory Shall not Small Sufficient Suitable Timely Typical User friendly Was
23 Requirement Writing 4: Use continuations carefully, they make traceability and verification difficult. Use when all items are to be verified by the same method at the same time. Example: The system shall report software status to the host interface under the following conditions: At system initialization. When the status of an external interface has changed. When a report has been requested. 5:Use examples, tables, figures etc., they are a great source of information and clarification. Make sure examples and notes are clearly marked as such (not part of requirement). For tables; specify if all, some or none of the cells are requirements. Clearly indicate if a figure or part of the figure, is part of the requirement, or is information.
24 Requirement Writing 6: Be consistent with names; always call the same entity by the same name. Example: If in some requirements the subject is called “the System,” and in others “ the URQ-65”, the names are not consistent. Always use the correct name for the level of specification. You can not verify a sub capability at a systems level. 7: If you use a TBD or TBR, have a plan. You must state who is responsible for the information, and when the it will be completed.
25 Requirement Writing 8: Make sure a requirement contains all the qualities of a good requirements Concise: Minimal, easily understood, a complete expression of a single thought, non-ambiguous; only one possible interpretation. Correct: An absence of errors of fact. Consistent: No conflicts between individual requirements, parts of a single requirement complement each other. Connectivity exists between the requirements; consistent words and terms Traceable: Know source of requirement and be able to allocate it, Uniquely identified for life. Never re-used identification on Project. Verifiable: Method (Test, Inspection, Demonstration, Analysis, Certification) Understand how requirement can be verified, and determine criteria for acceptance. Necessary:Can the system be complete without this requirement? Attainable: Is this requirement technically feasible within given time and cost? Modular:Will a change to this requirement have a big impact on the system? Can this requirement be easily used and monitored by other programs if needed? Restrictive– The requirement should written in such a way as to not limit implementation. Make sure the requirement states what needs to be done not how.
26 Requirement Writing 9: Conjunctions. There should be only one requirement per statement. A requirement should not contain “and” or “or”. Requirement which contain “and”, “or” or “and/or” probably contain more than one requirements. These hard to trace and completely verify. 10: Make sure that if a requirement references another document, that it does so correctly. State if reference is information or part of the requirement. Make sure references are listed in applicable document section and state what part of reference applies
27 Requirement Writing 11: Make sure Acronyms are used correctly. Place the acronym in the acronym list in the specification. Spell out the complete phrase followed by the acronym in parenthesis the first time used. The next time just use the acronym. Example: first use: “The SATCOM Antenna Interface Unit (SAIU) shall…”, second use “The SAIU shall…” 12: Overspecification leads to unfunded requirements, and can add duplicate requirements. The length of a requirement should not be excessive.
28 Requirement Writing 13: Use the requirement template There are four major parts to a requirement: Entities – Subject of the requirements (noun) Object of action (noun) Actions – What the subject does, contains imperative (verb) Conditions – What must be in place in order for this action to take place Constraints– Qualifies the action, performance The following is the structure of a basic requirement: [Conditions] [Subject] [Action] [Object] [Constraint] Example: When signal x is received [Conditions] ,the system [Subject]shall set [Action]the signal x received bit [Object]within 2 seconds [Constraint].
30 Requirement Elicitation The development process starts with understanding the client’s “business requirements”. For the success of any project, an agreed upon understanding of the desired capability is extremely critical. Requirements elicitation is the process of identifying the sources of requirements for a new project and obtaining those requirements from those sources. The most important outcome is that the people who need to understand the requirements can do so.
31 Requirement Elicitation There are many ways in which requirements can be gathered, there are several requirements elicitation techniques available to use You should gather requirements using whichever method works for you. Whether you prefer a written document, screen diagrams, prototyping or use cases Keep in mind that your choice of techniques will depend on your comfort level or familiarity, the complexity or nature of your project as well as the stakeholders you are talking to. Each requirements elicitation technique has its advantages and disadvantages and that there is no one technique that works for every situation. The following are some popular and recommended techniques for requirements elicitation:
32 Requirement Elicitation 1. Interviews: This technique uses a series of questions to extract information from the stakeholder, that focus on the client’s perspective, develops an understanding of the problem and finally evaluates the effectiveness of the meeting. 2. Document Review: All effective requirements elicitation involves some level of document analysis such as business plans, markets studies, contracts, requests for proposals, statements of work, existing guidelines, analyses of existing systems, and procedures. Improved requirements coverage results from identifying and consulting all likely sources of requirements.
33 Requirement Elicitation 3. Brainstorming: Brainstorming is a powerful technique because the most creative or effective ideas often result from combining seemingly unrelated ideas. Also, this technique encourages original thinking and the proposal of unusual ideas. Brainstorming involves both idea generation and idea reduction. The goal of the former is to identify as many ideas as possible, while the latter ranks the ideas into those considered most useful by the group. 4. Use Cases: A use case is a picture of actions that a system performs by depicting the actions. This should be accompanied by a textual description and should not be used in isolation from other requirements gathering techniques. Use cases and scenarios are known for facilitating team communication. They provide a context for the requirements by expressing the sequence of events and a common language for the end users and the technical team.
34 Requirement Elicitation 5. Requirements Workshops: This technique is considered very powerful for eliciting requirements because they can be designed to encourage consensus concerning the requirements of a particular capability. Other advantages that are achieved by this technique includes commitment of participants to the work products and project success, teamwork, resolution of political issues and reaching consensus on a host of topics. 6. Prototyping: This technique helps in building a quick and rough version of the desired system or parts of the system. This illustrates the capabilities of the system to users and designers. This technique serves as an excellent means of communication mechanism for all reviewers in understanding the interactions with the system. This sometimes gives an overly optimistic impression of completion possibilities since an impression is created that the developers are further along than is actually the case. Prototypes can be combined very effectively with other approaches such as JAD and models.
35 Requirement Elicitation 7. Storyboards: This technique is a set of drawings depicting a set of user activities that occur in an existing or envisioned system or capability. Storyboards may be thought of as forms of paper prototyping. In this technique, the Customers, Users or developers start by drawing pictures of the screens, dialogs, toolbars and other elements they believe the software should provide. These drawings are evolved by the group till the real requirements and details are worked out and agreed upon. This technique is in expensive and eliminates the risks and higher costs of prototyping. 8 Interfaces Analysis: One of the major causes of overrun is missing or incorrect interface. Identifying the external interfaces early clarifies product scope, aids risk assessment, reduces product development costs, and improves customer satisfaction. The steps of identifying, simplifying, controlling and monitoring interfaces help to reduce the risk of problems related to interfaces.
36 Requirement Elicitation 9. Glossary: to use the same language as your client. If the language is consistent, it greatly lowers the risk of misinterpretation of the requirements. Problems can develop if we didn’t use the same terms as the client. To avoid this problem is to include a glossary of terms and definitions in the requirements document. 10. Modeling: A model is a representation of reality or level of abstraction that is intended to facilitate understanding. They help eliminate ambiguities and inconsistencies and are correlated with the most successful projects.
37 Requirement Elicitation 11. Separate the problem and solution space: It is important to keep requirement elicitation implementation free. You should be working on understanding the problem, not solving it. Not keeping the requirements elicitation design free can create unnecessary restrictions and your product
38 Requirement Elicitation 12. Validating Requirements: One of the key activities to determine you have the right set of requirements is the requirement Validation: Before we accept requirements from Systems or a customer, we need to review the requirement set to see the quality of the requirements. This would let us know what is missing and what work needs to be done to the requirements. Can now develop a plan to address requirement needs.
Using Requirement Management Tools
The benefits of good requirements engineering tools...
Query attributes to find specific properties
“How many requirements are listed as high risk?”
Use traceability reports for checking dependencies
Before change is committed
Find “missing” links
“Which detailed requirements has no relation to a high-level user requirement?”
“Which higher level requirement has no lower-level requirement?”
“What lower level requirements are affected if a high level requirement changes?”
For each increment, if you develop incrementally with concurrent phases
For each variant, if you manage variants and product lines
41 Rational Requirements Definition and Management SolutionEnabling business & technology experts to build business value Business Processes Business Objectives
Achieve stakeholder consensus early and often in the development lifecycle to reduce rework and improve time to market
Improve collaboration among distributed teams to increase productivity and quality
Insure alignment of business and IT through linking and traceability of requirements artifacts to increase reuse and ensure effective software delivery
Use Cases Sketches Requirements Definition Rational Requirements Composer Elicit, capture, elaborate, review and discuss requirements using a variety of techniques and notations Rich text Documents Prototypes Visual Validation Storyboards Requirements Management Rational DOORS & Rational RequisitePro Understand the impact of change as it occurs and ensure full traceability to better manage project risk Search, filter on attributes Impact & Coverage analysis Traceability between related artifacts 41
42 More information Requirement management and definition webpage: Rational RM Solutions
43 Rational Publishing Engine: Document automation across the development lifecycle
Quickly and accurately create the right document for your development domain at the required time
Access data from a wide range of Rational tools, including:
Rational Quality Manager
Rational Requirements Composer
Access data from third party tools via XML and REST interfaces
Out-of-the-box document templates provided for quick ROI
44 RPE – Can create a document from multiple sources.This document extracts data from DOORS, ClearQuest and Rhapsody
45 Smarter healthcare Smarter automobiles Smarter electronic devices Smarter hybrid technologies Smarter defense systems Smarter energy Smarter Requirements Build Smarter Products Innovation for a smarter planet 45
47 Systems and Software Engineering Symposiums
48 Upcoming symposiums Landing page for all Symposiums: http://www.ibm.com/events/systemsengineeringsymposium