Block Definition and Internal Block Diagrams Flashcards
What can a block define?
- a type of logical or conceptual entity
- physical entity
- hardware, software, or data component
- person
- a facility
- an entity that flows through the system
- an entity in the natural environment
Is a block a type or a usage?
A type that owns a set of features (structural and behavioral) that describe the characteristics of an instance.
What is the symbol of a block?
a rectangle that is segmented into a series of compartments:
- name compartment (mandatory)
- parts
- operations
- value properties
- ports
What are part properties?
Describe the composition hierarchy of a block and define a part in the context of its whole.
What are value properties?
Describes quantifiable physical, performance, and other characteristics of a block such as weight or speed. It is defined by a value type that describes its valid range of values and quantity kind (length) and its units (inches). Can be related using parametric constraints.
What are properties?
Structural features of a block. THey have a type that defines its characteristics, which may be another block or something more basic like an integer.
What are the 3 categories of block properties?
- part properties: describe the composition of a block into its constituent elements.
- reference properties: properties whose values refer to parts of other blocks.
- value properties: describe the quantifiable characteristics of a block (weight, velocity)
What kind of properties does a properties compartment of a block contain?
any kind of properties
What is a composition relationship?
a whole-part relationship
What is the diagram kind of a block definition diagram, and which model elements can it represent?
Diagram kind: bdd
model elements: package, block, constraint block
What is the diagram kind of an internal block diagram and which model elements can it represent?
diagram kind: ibd
model elements: block
Which type of property is used to describe composition relationships between blocks?
Part properties describe the describe the decomposition of a block into its constituent elements.
What is the commonly used term for properties with a lower multiplicity bound of 0?
A lower bound (min instances) of 0 is called optional because the instance is not obligated to include any instances of the block at the part end.
What is the default interpretation of the multiplicity for both ends of an association when it is not shown on the diagram?
value of 1 is assumed
Give 2 situations in which the use of role names for the part end of a composite association should be considered
(p 148)
Names are used to distinguish 2 parts with the same type (block)
A name is given to a part when it does not adequately describe the role the part plays
Give 2 situations in which the use of role names for the part end of a composite association should be considered
(p 148)
Names are used to distinguish 2 parts with the same type (block)
A name is given to a part when it does not adequately describe the role the part plays
How are parts shown on an internal block diagram?
(p 147)
parts compartment of a block or as an association end, but not both. also as a box symbol with a solid boundary within the frame of the ibd
What does the presence of a connector between 2 parts imply?
(p 150)
The parts interact with each other in some way.
What are the 2 graphical mechanisms that can be used to represent properties nested more than 1 level deep on an ibd?
(p 156)
The nested parts can be represented by showing part symbols within part symbols
dot notation
What is the major difference between parts and references?
A part is an internal feature of block and is destroyed when the block is deleted. A reference property is a logical representation of another block that persists after the enclosing block is deleted.
What is the major difference between parts and references?
A part is an internal feature of block and is destroyed when the block is deleted. A reference property is a logical representation of another block that persists after the enclosing block is deleted.
What is the difference in representation between the symbol for composite association and reference association on a bdd?
composite: black diamond
bi-directional reference: solid line
uni-directional reference: solid like with arrowhead
What is an association block?
(p156)
combo of an association and a block
relates 2 blocks together but can also have internal structure and other features.
the internal structure can can be used to decompose the connector that is typed by the association block
How are the quantitative characteristics of blocks described?
value properties describe quantifiable physical performance and other characteristics of a block such as its weight or speed
What can value types describe about their values? (apart from the definition of a valid set of values)
Data type and units
What is a derived property?
(p 163)
their values are derived from other values.
typically calculated. indicated by placing a forward slash (/) in front of the property name.
How are probability distributions (such as an interval distribution) for a property represented in the values compartment on a bdd?
(p 164)
<>{p1=value, p2=value…} property name: type name
How are probability distributions (such as an interval distribution) for a property represented in the values compartment on a bdd?
(p 164)
<>{p1=value, p2=value…} property name: type name
Which SysML concepts can be used to represent items (things that flow)?
Item: describes things that flow
Blocks may contain special properties (flow properties) that define the items that can flow into or out of that block.
item flows specify what actually does flow on connectors between parts.
What does an item flow define?
(p 150)
the nature and direction of inputs and outputs between parts via the connector. An item flow may have associated property (item property) contained in the enclosing block, which identifies a specific usage of that item in the context of the enclosing block.
How is a proxy port specified?
(same as full ports) shown as rectangles intersecting the boundary of their parent symbols with floating string
<> port name: interface block name [multiplicity]
What is the difference between proxy and full ports?
Full port: can represent a physical part such as an electrical connector or a mechanical interface assembly, and therefore is a part in the system parts tree.
proxy ports: does not constitute a part of its parent block. it provides external access to and from the features of its parent block or the block’s parts without modifying its inputs or outputs.
What is the rule for assessing the compatibility of an item flow on a connector between 2 ports?
(p166)
For a flow to occur from a source part to a target part, both ends of the connector must have a flow property with at least a compatible type and direction.
flow property types are compatible if the type of the target flow property is either the same as or a generalization of the compatible if both properties have direction inout, or their directions are opposite of each other.
What is a behavior port on a block used for?
(p 178)
a proxy port can be defined to be a behavior port, which indicates that it provides access to features of its owning block rather than to the features of some internal part of the owning block. The flow properties of a behavior port can be mapped to the parameters of the bolck’s main (or classifier) block.
What is a behavior port on a block used for?
(p 178)
a proxy port can be defined to be a behavior port, which indicates that it provides access to features of its owning block rather than to the features of some internal part of the owning block. The flow properties of a behavior port can be mapped to the parameters of the bolck’s main (or classifier) block.
Name all 5 kinds of behaviors supported by SysML
(p 170)
- activity
- state machine
- interaction
- opaque
- function
What are the behavioral features of blocks used for?
(177)
blocks can own behavioral features that describe which requests a block can respond to.
a behavioral feature may have an associated method that is a behavior invoked when the block handles a request for the feature.
2 types of behavioral features: operations and receptions
What is a method?
(173)
A behavior owned by the block that only executes in response to a particular stimulus (when a request is made via a provided behavioral feature - operation or reception). It is related to the behavioral feature that was requested.
What do the required interfaces of a port specify?
(188)
A required interface on a port specifies one or more operations required by behaviors of the block (or its parts).
What do the provided interfaces of a port specify?
(188) A provided interface on a port specifies one or more operations that a block (or one or more of its parts) must provide.
Describe the ball-in-socket representation for the interfaces of ports.
(188)
The required and provided interfaces.
ball: a provided interface
socket: required interface
Name 4 types of classifiers
(190)
- blocks
- value types
- interfaces
- signals
- interface blocks
Name 4 aspects of a redefined property that a redefining property can change
(190)
Not all features added in subclasses are new; some are introduced to override or otherwise change the definition of an existing feature (redefinition)
1. restrict its multiplicity
2. add or change its default value
3. change the type of the feature to a more restricted type
4. provide a new distribution or change an existing distribution
How is a generalization relationship represented on a bdd?
A line between 2 classifiers with a hollow triangular arrowhead on the superclass end of the relationship
When specifying a generalization set, what is the coverage property used to define?
(194) Whether all the instances of the superclass are instances of one or another of the memebers of the generalization set. The 2 values of the coverage property are complete and incomplete
How are generalization sets represented on a bdd?
(194) yb a dashed line intersecting a set of generalization paths. The name of the generalization set and the values of the overlap and coverage properties are displayed floating near the line that depicts the generalization set.
alternatively by a tree with the set name and properties floating new the triangle symbol at its root.
What is a bound reference used for and how is it shown on an ibd?
it is a reference property of a block that is bound using a binding connector to some other nested property within the composition hierarchy. The properties that are connected using binding connectors must have compatible types and multiplicities.
If 1 property is defined to be a subset of another, what is the relationship between the elements of the subsetted property and the elements of the subsetting property?
superclass subclass
Name 2 ways in SysML of specifying a block configuration
it describes a specific structure and property values intended to represent a unique instance of a block in some known context. use the generalization relationship the configuration becomes a subclass of the block for which it is a configuration.
