UML Diagrams: Sequence Diagrams The Requirements Model, and The Dynamic Analysis Model

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UML DiagramsSequence DiagramsThe Requirements
Model, andThe Dynamic Analysis Model

• Instructor Dr. Hany H. Ammar
• Dept. of Computer Science and Electrical
  Engineering, WVU

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Outline

• Review of previous Lecture
• The Requirements Model and the Analysis model
• Introduction to Requirements Engineering
• Importance of Sequence Diagrams
• Rules of sequence diagrams
• Use Cases and Sequence Diagrams
• The System Sequence Diagrams
• The Sound Recorder Example
• The E-Commerce Example
• Other Examples

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Review of Previous lecture

• Review of development phases and UML Development
  - Overview
• Introduction and importance of Use Case Diagrams
• Use Case Diagram Rules
• Examples of Use Case diagrams
• Requirements Elicitation Process
• Identify Actors
• Identify Scenarios
• Identify Use Cases
• Refine Use Cases
• Identify Relationships between actors and Use
  Cases
• Identify Initial Analysis Objects
• Identify Non-functional requirements

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UML Development - Overview
REQUIREMENTS ELICITATION
Time
D
Requirements Engineering
System/Object SEQUENCE DIAGRAMS
A
T
A
ANALYSIS CLASS DIAGRAM(S)
StateChart DIAGRAMs
ANALYSIS Specify Domain Objects
D
I
OPERATION CONTRACTS
C
T
Architectural Design Include Design Objects
I
SUBSYSTEM CLASS/ OR COMPONENT DIAGRAMS
DESIGN SEQUENCE DIAG.
DEPLOYMENT DIAGRAM
O
N
DESIGN DIAGRAMS
A
R
Detailed DESIGN
Y
Object Design
IMPLEMENTATION Activity DIAGRAMS
IMPLEMENTATION CHOICES
IMPLEMENTATION
PROGRAM
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The Requirements Model and the Analysis Model
The Requirements Elicitation Process
Functional/ Nonfunctional Requirements
Use Case Diagrams/ Sequence Diagrams (the system
level)
The Object-Oriented Analysis Process
Static Analysis Dynamic Analysis
- Class Diagrams - State Diagrams/ Refined
Sequence Diagrams (The object level)
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What is Requirements Engineering ?

• Requirements Engineering

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What is Requirements Engineering?

• Requirements Management
• Requirements management activities include
  evaluating the impact of proposed changes,
  tracing individual requirements to downstream
  work products, and tracking requirements status
  during development
• Several Requirements management tools are
  available in industry

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What is Requirements Engineering?

• Major Requirements Management Tools
• 1. Caliber-RM by Technology Builders, Inc.
  www.tbi.com
• 2. RequisitePro by Rational Software Corporation
  www.rational.com
• 3. RTM Workshop by Integrated Chipware, Inc.
  www.chipware.com

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What is Requirements Engineering?

• Requirements Elicitation
• is the process of gathering the different types
  of requirements from suitable stakeholders.
• Business requirements describe why the product is
  being built and identify the benefits for both
  the customers and the business.
• User requirements, describe the tasks or business
  processes a user will be able to perform with the
  product. (Developing use-cases)
• Functional requirements describe the specific
  system behaviors that must be implemented
  (Developing usage scenarios)
• Non-functional requirements, describe the
  non-functional features such as quality
  attributes of Reliability, Performance,
  availability, and maintainability.

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What is Requirements Engineering?

• Requirements analysis
• Requirements analysis includes decomposing
  high-level requirements into detailed functional
  requirements, constructing graphical requirements
  models or logical models (structured Analysis
  models, or Object-Oriented Analysis models) (for
  developers), and building prototypes.
• Analysis models and prototypes provide
  alternative views of the requirements, which
  often reveal errors and conflicts that are hard
  to spot in a textual SRS.

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What is Requirements Engineering?

• Requirements Specification
• Specification key practice is to write down the
  requirements in some accepted, structured format
  as you gather and analyze them.
• The objective of requirements development is to
  communicate a shared understanding of the new
  product among all project stakeholders.
• Historically, this understanding is captured in
  the form of a textual Software Requirements
  Specification document written in natural
  language, augmented by appropriate analysis
  models. (to be discussed in detail)

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What is Requirements Engineering?

• Requirements Verification
• Verification involves evaluating the correctness
  and completeness of the requirements, to ensure
  that a system built to those requirements will
  satisfy the users needs and expectations. The
  goal of verification is to ensure that the
  requirements provide an adequate basis to proceed
  with design
• Prototyping (or executable specifications) is a
  major technique used in verification. Examples
  include GUI development for user requirements
  verification, and Formal requirements
  specification environments

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Outline

• The Requirements Model and the Analysis model
• Introduction to Requirements Engineering
• Importance of Sequence Diagrams
• Rules of sequence diagrams
• Use Cases and Sequence Diagrams
• The System Sequence Diagrams
• The Sound Recorder Example
• The E-Commerce Example
• Other Examples

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Importance of Sequence Diagrams

• Depict object interactions in a given scenario
  identified for a given Use Case
• Specify the messages passed between objects using
  horizontal arrows including messages to/from
  external actors
• Time increases from Top to bottom

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Rules of Sequence Diagrams

• Sequence Initiation

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Rules of Sequence Diagrams

• Identify objects needed to support use case,
  determine sequence of internal events following
  the external initiating event
• Diagrams that are not initiated with an external
  actor represent only a partial sequence
• Partial sequence diagrams should clearly identify
  the actor initiated sequence diagrams from which
  they are launched

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Rules of Sequence Diagrams

• Messages specified on interactions can be
  synchronous or asynchronous

Synchronous call
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Rules of Sequence Diagrams

• Asynchronous call

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Rules of Sequence Diagrams

• Display operation names on call arrows

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Rules of Sequence Diagrams

•  Compound and Simple Iteration

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included sequence diagrams
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Showing alternate behavior in a sequence diagram
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Showing Extension Point
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Specifying Timing Requirements
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Outline

• The Requirements Model and the Analysis model
• Introduction to Requirements Engineering
• Importance of Sequence Diagrams
• Rules of sequence diagrams
• Use Cases and Sequence Diagrams
• The System Sequence Diagrams
• The Sound Recorder Example
• The E-Commerce Example
• Other Examples

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Recall Requirements Elicitation Process

• The process of requirements elicitation consists
  of the following steps
• Identify Actors
• Identify Scenarios
• Identify Use Cases
• Refine Use Cases
• Identify Relationships between actors and Use
  Cases
• Identify Initial Analysis Objects
• Identify Non-functional requirements

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Requirements Elicitation ProcessStep 4. Refining
Use Cases

• System Sequence Diagrams
• System sequence diagrams establish the dynamic
  behavior in terms of key scenarios of the system
  for each use case
• The system sequence diagram models a scenario of
  the system interactions with the environment for
  a given use case
• Input/output events are clearly identified in
  each sequence diagram,
• The State of the system before and after each
  event are also depicted
• Different diagrams model scenarios with the
  normal flow of events and the abnormal flow of
  events

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Sequence Diagrams and Use CasesSystem Sequence
Diagram
The use case diagram Of system S
The sequence diagram of use case UC1 for system S
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UML Use Case Diagrams The Requirements Model
Case Study
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UML Use Case Diagrams The Requirements Model
Digital Sound Recorder Case Study

• A sequence diagram displays object interactions
  arranged in a time sequence capturing a specific
  scenario of interactions in a use case supported
  by the system

Time
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Example Use Case Diagram of E-Commerce Example
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• Place Requistion

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Other Examples of Sequence Diagrams
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A Simple Example of Using UML2

• EXAMPLE SATELLITE CONTROL SYSTEM

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Example of Software Architecture Using UML2

• SATELLITE CONTROL SYSTEM Architecture

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A Simple Example Using UML2

• SATELLITE CONTROL SYSTEM Architectural behavior