Real Time Systems Modeling Structure in UML (Part I)

Structure (part1) - 2 Outline  Quick Review of UML  Modeling real-time systems with UML  Basic Structural Elements  Capsules  Ports  Protocols  The Capsule Structure Diagram

Structure (part1) - 3 Quick Review of UML  logical view diagrams  class diagram  collaboration diagram  sequence charts  state diagrams  logical view modeling elements  classes  relationships  packages

Structure (part1) - 4 Quick Review of UML (cont’d)  other views  use-case view  implementation (component) view  deployment view  concept of stereotyping  allows for domain specific semantics without “bastardizing” UML > ClassA or

Structure (part1) - 5 Modeling RTS in UML - Overview  A system will be modeled as multiple communicating active objects (capsules)  system behavior will be modeled through the state machines of the capsules  capsules can only communicate by sending messages through their ports  communication between ports is defined by a protocol  messages control (trigger) the transitions in the receiving capsule’s state machine

Structure (part1) - 6 Capsule  based upon a common pattern found in RTS: active object  ultra light weight concurrency  run to completion  executable  fundamental modeling element  a stereotype of a UML class  has attributes  has operations  has a state machine  has ports > CapsuleA > CapsuleA

Structure (part1) - 7  Capsule  contain only protected or private operations and attributes ClassA CapsuleA Capsule vs Class (1) “strong encapsulation”  Class  contain public, protected or private attributes and operations

Structure (part1) - 8  Capsule  communicate by sending messages (signals) through contained ports ClassA CapsuleA Capsule vs Class (2)  Class  communicate by calling operations on other classes PortA

Structure (part1) - 9  Capsule  elemental behavior is specified by a capsule’s state machine ClassA doThisMethod( ) CapsuleA Capsule vs Class (3)  Class  elemental behavior is specified by operations S1 S2

 Class  system behavior is expressed as a group of collaborating objects 2: howHigh():int Structure (part1) - 10  Capsule  system behavior is expressed as a sequence of inter-capsule messages Capsule vs Class (4) A:CapsuleAB:CapsuleB how high jump number A:ClassA B:ClassB 1: jump( )

Structure (part1) - 11 Capsule Role  An instance of a capsule class  changes to the role only affect the role not the class  has cardinality  strongly owned by the containing capsule  composition - fixed role (norm)  aggregation - optional or plug-in CapsuleACapsuleBCapsuleC roleCroleB

Structure (part1) - 12 Port (1)  isolates a capsule’s implementation  the means by which capsules communicate  send and receive messages  are owned by the capsule instance  created and destroyed with the capsule CapsuleACapsuleB > ProtocolP

Structure (part1) - 13 Port (2)  defines a capsule interface  is a protocol role  an instance of a protocol  only compatible ports may communicate  all ports have a “send” operation  port1.myMessage().send() CapsuleACapsuleB > ProtocolP myMessage()

Structure (part1) - 14 Protocol (1)  contract between capsules  a specification of a set of messages received (in) and sent (out) from the port  defines the port type  recall port compatibility  a stereotype of a UML collaboration ProtocolP CapsuleACapsuleB how high jump OK number messageOut( ) messageIn( )

Structure (part1) - 15 Protocol (2)  Each capsule role typically has an associated protocol for every other capsule role with which it associates  defines the services one capsule role provides another  a set of signals (and associated data) required to perform the capsule role’s job CapsuleBCapsuleC > ProtocolP CapsuleA

Structure (part1) - 16 Capsule Structure Diagrams  visually defines the structure of a capsule  internal structure specified by capsule roles  capsule roles communicate via ports  stereotype of a UML collaboration diagram  protocols not visible (only their instances - ports)  provides the support necessary to add “code generation” Containing capsule

Structure (part1) - 17 Summary Overview of real-time UML modeling  A system will be modeled as multiple communicating capsules  system behavior will be modeled through the state machines of the capsules  capsules can only communicate by sending messages through their ports  communication between ports is defined by a protocol  messages control (trigger) the transitions in the receiving capsule’s state machine