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Faculty of Engineering - Universitas Indonesia
Electrical Engineering Department
Requirement Requirement Engineering Engineering (part 1)(part 1)
Kalamullah Ramli
2Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Requirement Study
o Requirement are ubiquitous part of our lives
o Understand the requirement through communication
o Communication Problem?• People are hard to understand!
Human Nature
3Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
4Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Change is Constant
o What makes the change?• Human nature• Society • Organization• Competitors
o DESIGN: shooting at moving target!
5Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Why Requirement Study?
o Limitation of the designerso Motivationo Reduce the total cost
o How far shall we make the requirement analysis?
Failure of Requirement Analysis
o The penalty of getting Requirement Engineering (RE) wrong is high
o Even the system did not fall, user is sub-optimal and design costs are wasted
6Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Cases of Failure if RE
o How much library functions do you use?
o New software development (less than 30% in the market)
o How much mobile phone functions did you use?
o .....
7Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Analysis Methods
o System analysis – top down decomposition
o Establish goal/functions representation in, e.g., data flow diagrams
o Quick and dirty methods
8Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Obstacles to RE
o Tacit knowledgeo Ambiguityo Attitude and opinions
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Three Dimensions
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Four Worlds Framework
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User Requirements Framework
o User Context and Early Designo Prototype and User Testo User requirements documentation
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Users’ Limitation
o Users do not have clear vision of what they want
o Goal can be fuzzyo Do not know what is technical
possibilityo But,once they get, they can see
how it can be improved .... or they simply do not like it
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Requirement Types and Pathway
o High level functions, towards the final goal
o Detail functionso How functions should worko Constraint on system operationo Statement about performanceo Implementation constraints
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Requirement Types and Pathway
o Functional requirements• The goals
o Non functional requirements (NFR)• Quality• Performance• Environment issues• Cost• Time
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Constraints
o > are conditions or laws that the system will have to obey during operation or during design• Human cognitive• Physical• Environmental• Costs• Legal
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User Requirements Documentation
o General system characteristicso Organizational structureo Tasks scenario and interaction stepso Technical environmento System functions and featureso User interface designo User supporto Physical environment
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User Requirements Documentation
o Social and organizational environment
o Standards and styleguides to apply
o Test plan
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Documentation
o Natural language?o Technical language?o Long, dense text?
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Documentation
o Structure standards (IEEE 830, Mazza et al 1994)• Natural language, but short and
avoid ambiguity• Structured, defined items• Management tools for diagram• Categorize stakeholders and
different requirements
20Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
User Context and Early Design
o Identify users and stakeholders, and their characteristics
o Describe technical/physical/social and organization environment
o Review: current process, similar systems and products
o Perform expert review of design
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RE Tasks and Processes
o No “cook book”, but “roadmap”o Dynamically: pre-design and within
design processo Common methods:
• Interview • Observation• Questionnaires• Text and document analysis
o Set Scope and Bainstoming
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User Requirement Methods
o Funcationality Matrixo Storyboardingo Task analysiso Task allocation
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Functionality Matrix
o This method is useful when the number of possible function is high
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Goal Analysis
o Goal hierarchy and decomposition• e.g. Final goal: Increase customers’
satisfaction• Reduce processing time for constraint• Improve personal service in ordering• Reduce lead time for delivery
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Events Analysis
o Outcome is to scope the system in terms of its input, output, and major functions
o Object oriented: focus on evento Event process chains
• Where does the output from the process go to?
• What process or fuction is responsible for responding to this even?
• Who or what is the destination of this even and why do they want it?
• Input-Process-Output (IPO) charts26Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Modeling
o Analysis + Modeling = elaborate requirements
o Different methods• Semantic model• Conceptual model
• Process/information flows• Data flow diagram• Data structures• Entity Relationship
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Faculty of Engineering - Universitas Indonesia
Electrical Engineering Department
Requirement Requirement Engineering Engineering (part 2)(part 2)
Kalamullah Ramli
Basic Objectives of RA
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o To delineate the data requirements of the enterprise in terms of basic data elements
o To describe the information about the data elements, and the relationships among them needed to model these data requirements
o To determine the types of transactions that are intended to be executed on the database, and the interaction between the transactions and the data elements
Basic Objectives of RA
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o To define any performance, integrity, security, or administrative constraints that must be imposed on the resulting database
o To specify any design and implementation constraints, such as specific technologies, hardware and software, programming languages, policies, standards, or external interfaces
o To thoroughly document all of the proceeding in a detailed requirement specificationo Data element can also be defined in a data
dictionary system, often provided as an integral part of the database management system
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i* Family of Model
Validation
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o User’s understanding of the requirement specification
o User agree that it accurately reflect their wishes
o Different prototypes and scenario are normally used
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Verification
o Requirement specification behaves correctly and does not violate any of the laws specified by the users
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Boundary
o The system built behaves correctly (verification)
o The system output makes sens to the user (validation)
o However, boundary can be blurred
Balance the Requirements
o Different stakeholders have different requirements
o Trade-off analysis methods, decision making table, models, relationship maps, etc
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Conduct Negotiation
o Structure options and choiceso Establish judgment criteriao Explain the optionso Vote?o Diagnose the cause of
disagreement
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Conflicts
o Probably due to lack of shared understanding• Handling personal attach – steering
sensitive topics away from them• Blocking: challenge those who said: “it
won’t work ...”, “it can’t be done .... “• Trade-off between NFR• Test Assumptions• Benefit Analysis
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Trade-off Between NFR
o Quality vs Delivery timeo Cost vs Development timeo Security vs Accesso Functional vs Usability,
Complexity Reliability, and Maintainability
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Functional Allocation
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o Automated or Manualo Management Levelo Operational Levelo Some Guidelines
• Machine: repetitive processing, high volume data processing, monitoring, deterministic tasks
• Human: recognition, reasoning, flexible, problem solving, non-deterministic tasks and unpredicted events
Initial Pathways and Scoping for Requirements
o Policy-, or business-driveno Problem-initiatedo Technical Driveno External Environment
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Policy-, or Business-Driven
o Business, social-economical theories
o Williamson 1980 theory: predict the type of organizational relationship according to the goods that a customer wants to acauire from a supplier
o Top-down decomposition
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Problem-initiated
o Existing system has problemo Event-based analysis
• Event-tree analysis• Failure mode-event analysis• Cause-effect net
o Model-based analysis
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Technical-driven
o User’s immediate goals is often to acquire new technology
o User’s work goal analysiso Fit the new technology with existing
systemo Demon the functions of the new
technical
43Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
44Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Applications & Technology Factors
External Environment
o NFR• Safety• Security• Accessibility• Usability
o Market
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Conversation
o Rasmussen’s Framework (1986)Communication is generally an automatic and hence skilled process so it is prone to slip- and lapse- error in failure to listen and poor generation
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Conversation
o Discourse theory (Clark 1996)• People communicate to establish
and achieve shared goals• Motivated by purpose• Cylce of exchanges• Common ground of understanding
o Discourse: is the branch of linguistics that investigates how meaning is derived in context
47Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Conversation and Context
o Meaning is often constructed by the context of conversation• Role of speakers• Place• Time
o Shared beliefo Shared externally perceivable
entities
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