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© 2011 IBM Corporation
Michelle Specht
Writing and Eliciting Good Requirements
Michelle Specht
7/23/2011
© 2011 IBM Corporation
Software and Systems Engineering | Rational
2
Agenda
The Importance of Good Requirements
The Challenges of Developing Good Requirements
Writing Requirements
Requirements Elicitation
Using Requirements Management tools
© 2011 IBM Corporation
Michelle Specht
The Importance of Good Requirements
© 2011 IBM Corporation
Software and Systems Engineering | Rational
4
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
Why We Need Requirements
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Software and Systems Engineering | Rational
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Requirements Definition and Management Business Realities Traditional methods yield excess rework, delays & poor quality
20
200
Rel
ati
ve
Co
st
to R
ep
air
AcceptanceQA TestCodingDesignAnalysis
0
Maintenance
10
5
50
1-2
Lost Opportunity
Late to market by 6 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
-Standish Group
Cost
70-80% of development costs are spent identifying and correcting defects
More than 40% of development budget will be consumed by poor requirements
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Software and Systems Engineering | Rational
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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?
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Software and Systems Engineering | Rational
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What can happen when Requirements are not done right:
© 2011 IBM Corporation
Michelle Specht
The Challenges of Developing Good Requirements
© 2011 IBM Corporation
Software and Systems Engineering | Rational
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Poor Requirements Practices Pose Significant Challenges Across Teams
We struggle with budgets and can’t consistently meet
customer needs
Executive
Analyst
It’s hard to accurately capture requirements & make sure
they are implemented & tested
We can’t keep up with requirement changes and
know what is most important to develop and test
Development and Test teams
Quality Manager
Improve Quality
Efficiency
+Innovation
Reduce Cost
Accelerate Delivery
Time
We are continuously pushed to increase quality with less
resources!
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Software and Systems Engineering | Rational
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Safety
Regulatory compliance
Development timescales
Project scale
Project life
…
Cost
Quality Time
Different industries have different needs…
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Software and Systems Engineering | Rational
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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.
© 2011 IBM Corporation
Software and Systems Engineering | Rational
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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
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Software and Systems Engineering | Rational
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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
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Software and Systems Engineering | Rational
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Requirements come from everywhere
Requirements
Obj
ectiv
eG
oalAim
Reg
ulat
ion
Criterion NeedFeat
ureFunction R
ule
Ris
k
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Software and Systems Engineering | Rational
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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
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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
……….
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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
© 2011 IBM Corporation
Michelle Specht
Writing Requirements
© 2011 IBM Corporation
Software and Systems Engineering | Rational
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.
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Software and Systems Engineering | Rational
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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.
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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.
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Software and Systems Engineering | Rational
22
Requirement Writing
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
3: Do not use weak phrases and subjective words.
Following are words and phases not to use when writing a requirement:
© 2011 IBM Corporation
Software and Systems Engineering | Rational
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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.
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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.
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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.
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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
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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.
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Software and Systems Engineering | Rational
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Requirement Writing
13: Use the requirement templateThere 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].
© 2011 IBM Corporation
Michelle Specht
Requirements Elicitation
© 2011 IBM Corporation
Software and Systems Engineering | Rational
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.
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Software and Systems Engineering | Rational
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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:
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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.
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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.
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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.
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Software and Systems Engineering | Rational
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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.
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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.
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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
© 2011 IBM Corporation
Software and Systems Engineering | Rational
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.
© 2011 IBM Corporation
Michelle Specht
Using Requirement Management Tools
© 2011 IBM Corporation
Software and Systems Engineering | Rational
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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?” Coverage analysis
– “Which higher level requirement has no lower-level requirement?”
Impact analysis– “What lower level requirements are affected if a high
level requirement changes?” Keep traceability
– For each increment, if you develop incrementally with concurrent phases
– For each variant, if you manage variants and product lines
The benefits of good requirements engineering tools...
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Software and Systems Engineering | Rational
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Rational Requirements Definition and Management SolutionEnabling business & technology experts to build business value
41
Requirements ManagementRational DOORS & Rational RequisitePro
Understand the impact of change as it occurs and ensure full traceability to
better manage project risk
Search, filter on attributes
Traceability between related
artifacts
Impact & Coverage analysis
Business Objectives
Business Processes
Storyboards
Requirements DefinitionRational Requirements Composer
Elicit, capture, elaborate, review and discuss requirements using a variety of techniques and notations
Rich text Documents
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
Prototypes
Visual Validation
Sketches
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More information
Requirement management and definition webpage:
Rational RM Solutions
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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:
DOORS ClearCase/ClearQuest Focal Point System Architect Rational Quality Manager RequisitePro Rhapsody Rational Requirements Composer Team Concert Test Manager
Access data from third party tools via XML and REST interfaces
Out-of-the-box document templates provided for quick ROI
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RPE – Can create a document from multiple sources.This document extracts data from DOORS, ClearQuest and Rhapsody
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Smarter healthcare
Smarter electronic devices
Smarter defense systems
Smarter energy
Smarter hybrid
technologies
Smarter automobiles
Smarter Requirements Build Smarter Products
45
Innovation for a smarter planet
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Systems and Software Engineering Symposiums
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Upcoming symposiums
Landing page for all Symposiums: http://www.ibm.com/events/systemsengineeringsymposium
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Upcoming symposium
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