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SEM4610 (Block Definition Diagrams (When to create BDD (stakeholder needs…

- - - - Elements of definition: elements that appear on BDD
        
        blocks
        
        actors
        
        value types
        
        constraint blocks
        
        flow specifications
        
        interfaces
  - - - package
      - model
      - modelLibrary
      - view
      - block
      - constraintBlock
      - serves as a namespace
        
        a model element that's allowed to contain other model elements
  - - - structural (aka properties)
        
        part properties
        
        represents a structure that's internal to a block
        
        ownership
        
        hardware domain: refers to physical composition
        
        software domain: refers to one object's responsibility for the creation and destruction of another object
        
        SysML definition: a part property can belong to only one composite structure at a time
        
        <part name> : <type> [<multiplicity>]
        
        <part name> : modeler defined<type> : name of a block you've created<multiplicity> : constraint on the no. of instances that the part property can represent within the composite
        
        multiplicity can be set as "0..*" where the asterisk means "or more", representing an unconstrained no. of instances
        
        if no multiplicity given, default is 1 (1..1)
        
        collection of instances: multiplicity with upper bound more than 1 (e.g. 0..10, 1..2, *)
        
        reference properties
        
        represents a structure that's external to a block
        
        does not convey ownership
        
        "needs" relationship
        
        a block with a reference property needs that external structure for some purpose, wither to provide a service or to exchange matter
        
        <reference name> : <type> [<multiplicity>]
        
        default multiplicity = 1
        
        collection (of instances)
        
        value properties
        
        represents a quantity (of some type), bool, or string
        
        useful in conjunction with constraint properties to construct a mathematical model of the system
        
        <value name> : <type> [<multiplicity>] = <default value>
        
        <default value> : optional information, represents value assigned to the property
        
        default multiplicity = 1
        
        collection (of instances)
        
        can be assigned or derived
        
        derived value has a "/" in front of its name
        
        constraint properties
        
        represents a mathematical relationship that is imposed on a set of value properties
        
        often an equation or inequality
        
        <constraint name> : <type>
        
        blocks can own constraint properties (to constrain value properties)
        
        constraint properties are typed by constraint blocks, which generally encapsulate mathematical relationships
        
        ports
        
        represents a distinct interaction point at the boundary of a structure
        
        through which external entities can interact with that structure
        
        to provide or request a service, or to exchange matter, energy, or data
        
        when added, it's like modeling a structure as a black box with respect to its environment
        
        structure's internal implementation hidden from clients
        
        clients only know structure's interface
      - behavioural
- - - - Vocabulary
        
        Consists of graphical notations that have specific meanings
        
        Example: Arrow with a dashed line has a different meaning as compared to an Arrow with a solid line
      - Grammar and notations
        
        Defined in a standards specification owned and published by
        
        Object Management Group(OMG)
        
        A consortium of hundreds of compuer industry companies,government agencies and academic institutions
        
        Collaborate to develop a set of enterprise integration standards and promote business technology
        
        SysML specification
        
        Attempts to define grammar of this modeling language
        
        in a way that is Precise and unambiguous
        
        And it largely succeeds but text in the specification can be difficult to
        
        Parse
        
        Process
        
        Not meant for beginners
  - - - System Engineers felt UML didnt sufficiently capture all the meaningful concepts in systems engineering
        
        Software engineers use a data type(e.g. Integer to specify the type of an attribute within a class, the type of object that can flow through an activity
        
        System engineers care about other types of things that can flow such as matter and energy not just data
        
        The Datatype concept wasnt sufficient thats why SysML introduces a new kind of model element
        
        ValueType which extends the concept of DataType to provide a more neutral term for the broader set of types in the systems engineering domain
  - - - Displays text-based requirements
      - Relationship between requirements(containment, derive requirement and copy)
      - Relationship between requirements and other model elements that satisfy,verify and refine them
      - Allowable Model Element Types: package, model, modelLibrary, view, requirement
    - - Internal Block Diagram
        
        Parametric Diagram
        
        Used to express how one or more constraints specifically
        
        Equations and Inequalities
        
        Bound to the properties of a system
        
        Support engineering analyses
        
        Availability
        
        Power
        
        Reliability
        
        Mass
        
        Performance
        
        Cost
        
        Used to support trade studies of candidate physical architectures
        
        Allowable Model Element Types: block, constraint block
        
        Specifies the internal structure of a single block
        
        Shows the connections between the internal parts of a block and the interfaces between them
        
        Allowable Model Element Type: Block
      - Package Diagram
        
        Allowable Model Element Types: Package, model, modelLibrary, view, profile
      - Block Definition Diagram
        
        Displays elements such as
        
        Blocks
        
        Value Types(elements that define the types of things that can exist in a operational system)
        
        Relationships between the elements
        
        Common uses include
        
        Display system hierarchy trees and classification trees
        
        Allowable Model Element Types: package,model, modelLibrary, view, block, constraintBlock
    - - Activity Diagram
        
        Specify behavior
        
        Focuses on the flow of control
        
        Transformation of inputs into outputs through a sequence of actions
        
        Commonly used as an analysis tool to understand and express the desired behavior of a system
        
        Allowable Model Element Types: activity
      - Use Case Diagram
        
        Convey use cases that a system performs
        
        Actors that invoke use cases and participate in them
        
        A black box view of the services a system performs in collaboration with its actors
        
        Allowable Model Element Types: Package, model, modelLibrary, view
      - Sequence Diagram
        
        Specify Behavior
        
        Focuses on the interactions of the different parts of a block
        
        Interaction via operation calls and asynchronous signals
        
        Excellent for specifying test cases
        
        Allowable Model Element Types: interaction
      - State Machine Diagram
        
        Specify behavior
        
        Focuses on the set of states of a block and the possible transitions between those states in response to event occurences
        
        Similar to a sequence diagram
        
        A precise specification of a block's behavior that can serve as input to the development stage of the life cycle
        
        Allowable Model Element Types: stateMachine
  - - - Region inside the frame where model elements and relationships can be displayed
    - - Upper left hand corner with its lower-right corner cut off
      - Name of Model Element
      - Kind of Diagram
        
        The 9 kinds of SysML Diagrams defined by their abbreviations
        
        E.g. block definition diagram(bdd)
      - Name of diagram
      - Type of Model Element
        
        Indicate where the elements on the diagram can be found within the model
        
        The model element represented by the diagram defines the namespace - the container element within the model hierarchy - for the other elements shown on the diagram
      - bdd[package]Structure[DellSat-77 Satellite Subsystems]
        
        Tells us that the blocks in the content area are contained in(nested under) the Structure package in the model hierarchy
        
        Gives us a sense of how the elements are partitioned in the model
        
        This aids us in navigating the model
    - - Outer Rectangle
- - - - The connections among part and reference properties
      - types of
        
        Matter
        
        Energy
        
        Data
        
        Flow across the connections
        
        :<3:
      - Services that are provided and required across the connections
  - - - IBD is used to display a valid configuration of that block
        
        A specific set of connections among the block's properties
  - - - A rectangle with a solid border
        
        <part name> : <type> [multiplicity]
        
        example: mod:Modulator[1]
  - - - A structure that the block needs for some purpose
        
        To invoke behaviors
        
        exchange matter, energy or data
    - - a rectangle with a dashed border
        
        <reference name> : <type> [multiplicity]
        
        eps: Electrical Power Subsystem (the multiplicity is 1 at the top right hand corner)
  - - - Conveys that the two structures will have some way to access each other within a correctly assembled and operation system
      - Can be either part property, reference property or both
    - - Used to convey additional information
        
        Format for that name string is <connector name> :<type>
      - Type must be the name of an association that you have created between 2 blocks somewhere in your system model
        
        The association must relate the same 2 blocks that type the two properties at the ends of the connector
  - - - A filled-in triangular arrowhead on a connector that joins 2 flow ports
- - - - SE will manually generate some subset of artifacts
        
        Produced in a form of disjoint set of text documents, spreadsheets, diagrams and presentations
      - Expensive
        
        incur a significant % of total life cycle cost maintaining the artifacts
      - Time consuming and error prone
    - - Primary artifact: system model created by a modelling tool
        
        All other artifacts are secondary - automatically generated from the modelling tool
        
        Merely views of the underlying system model
        
        Central repository for design decisions
        
        Design decisions captured as model elements
        
        If model changes, diagram changes
        
        Changes made automatically
        
        Hence no opportunity for inconsistency
      - Promises increased quality and affordability
  - - - semi-formal language that defines:
        
        the kinds of elements you're allowed to put in your model
        
        the allowable relationships between them
        
        the set of notations you can use to display the elements and relationships on diagrams
      - SysML is commonly used
        
        to construct models of a system's infrastructure, behavior, requirements and constraints
      - standardized medium for communication
    - - documented set of design tasks that ensures that everyone on the team is building the system model consistently and working toward a common end point
      - scope of model
        
        scope is determined by purpose of the MBSE project
        
        determines modelling method
        
        sets goalpost that team is working towards; enables team to determine completion
    - - Special class of tools
        
        designed and implemented to comply with the rules of one or more modelling languages
        
        Enables construction of well-formed models
      - Create a model
        
        A set of elements and relationships between elements
        
        A set of diagrams that serve as views of the underlying model
      - Instantaneously updates all diagrams that display the same element that is being modified
  - - - MBSE does not eliminate the difficult work of architecting and designing a system well.
      - MBSE does not eliminate the need for engineering rigor during system specification and design
  - - - Promises to deliver a greater return on investment than traditional document-based approach
      - Practice rests on 3 pillars: language, method and tool