Post on 08-May-2015
Faculty of Engineering - Universitas Indonesia
Electrical Engineering Department
Requirement Engineering Requirement Engineering (part 1)(part 1)
Prof. Dr.-Ing. 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!
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Why Requirement Study?
o Limitation of the designers
o Motivation
o 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 in 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 .....
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Analysis Methods
o System analysis – top down
decomposition
o Establish goal/functions representation
in, e.g., data flow diagrams
o Quick and dirty methods
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Obstacles to RE
o Tacit knowledge
o Ambiguity
o 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 Design
o Prototype and User Test
o User requirements documentation
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Users’ Limitation
o Users do not have clear vision of what
they want
o Goal can be fuzzy
o Do not know what is technical possibility
o 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 functions
o How functions should work
o Constraint on system operation
o Statement about performance
o Implementation constraints
14Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
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 characteristics
o Organizational structure
o Tasks scenario and interaction steps
o Technical environment
o System functions and features
o User interface design
o User support
o 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
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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 process
o Common methods:
• Interview
• Observation
• Questionnaires
• Text and document analysis
o Set Scope and Bainstoming
22Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
User Requirement Methods
o Functionality Matrix
o Storyboarding
o Task analysis
o Task allocation
23Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Functionality Matrix
o This method is useful when the number
of possible function is high
24Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
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 event
o 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) charts
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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 Engineering Requirement 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
30Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
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 choices
o Establish judgment criteria
o Explain the options
o 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 time
o Cost vs Development time
o Security vs Access
o Functional vs Usability,
Complexity Reliability, and
Maintainability
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Functional Allocation
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o Automated or Manual
o Management Level
o Operational Level
o 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-driven
o Problem-initiated
o Technical Driven
o External Environment
40Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
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
41Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Problem-initiated
o Existing system has problem
o Event-based analysis
• Event-tree analysis
• Failure mode-event analysis
• Cause-effect net
o Model-based analysis
42Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
Technical-driven
o User’s immediate goals is often to
acquire new technology
o User’s work goal analysis
o Fit the new technology with existing
system
o 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
46Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia
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 belief
o Shared externally perceivable entities
48Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia