According to James Martin, a Methodology is “a collection of related processes, methods, and tools.”
Welcome to Modeltron, the elements of systems modeling.
According to James Martin, a Methodology is “a collection of related processes, methods, and tools.”
There is a nuanced difference between an Activity Final Node and a Flow Final Node on a SysML Activity diagram. The Activity Final Node, when reached, terminates the execution of the entire Activity. When the Flow Final Node is reached, all tokens (either Control or Object Tokens) are consumed, but Activity execution continues.
A Control Operator is a special type of Action Node which produces a control token on its output Parameter (i.e., activity parameter or action pin). It is commonly used to dictate (i.e., control) the flow of Object Tokens in an Activity. Similarly, it can be used to disable Object Token flow.
SysML uses a variety of elements to represent the logical flow of control of the system behavior. These elements include Fork Nodes, Join Nodes, Decision Nodes, Merge Nodes, Initial Nodes, Activity Final Nodes, and Flow Final Nodes.
Probabilities may be applied to control flows and parameter sets on an activity to indicate the likelihood the path of the control flow will be taken or the probability the parameter set will receive values.
Activity Parameters may be bundled together into Parameter Sets. Only one Input Parameter Set may hold tokens and only one Output Parameter Set may hold tokens on an Activity, although a single Activity Parameter may belong to more than one Parameter Set.
The «nobuffer» and «ovewrwrite» stereotypes can be applied to object nodes to model whether incoming tokens are discarded if a token is already present or overwrite the existing token in the object node.
If an Object Node is typed by a Block which possesses a state machine, then an Object Node, Activity Parameter, or Action Pin typed by that Block can require that the State Machine exist in a certain state before an Object Token may be passed.
Central Buffers and Data Stores are special types of Object Nodes, displayed on an activity diagram, which store Object Tokens.
Additional properties added to an element are called tags. The concept of a tag is related to that of a stereotype.
Interfaces describe provided and required behavior. Oftentimes these behaviors are services offered or needed by the block which owns the port to which the Interfaces are allocated.
The «optional» stereotype may be applied to parameters on an activity diagram indicating that the parameter is “not required to have a value for the activity…to begin or end execution.”
If the “IsStream” attribute of an activity parameter is true, then that parameter “may accept values while its behavior is executing” if it is an input parameter or it “may post values while the behavior is executing.”
Rate describes flow, which in SysML can be either continuous or discrete.
Conjugated Ports have been deprecated according to the SysML 1.6 (beta) specification, para C1.2. From SysML 1.6 onward, Conjugated Interface Blocks will be used to type Ports.
Structured value types describe a custom (and sometimes complex) data structure which can be used to type a value property.
Subclass «block» elements which inherit from a superclass «block» may be organized into groups, called Generalization Sets.
A derived property of a «block» depends upon other value properties of the «block».