UCM Scenarios Data Model

Overview

• This page defines the data model that will be implemented in jUCMNav.
• UCMNav supports only global boolean variables.

Proposal / Recommendation

• We focus on the core behaviour, to be improved at a later date.
• Java style comments are supported (/* ... */ and // ... )

Supported Data Types

• Boolean
  • Examples: true, false (integers cannot be cast to Boolean in conditions)
  • Global variables defined in a central location.
    • DA: I don't mind having global ones; there are many things to resolve before considering local ones
• Integers
  • Examples: -10, 0, 1, 2, 3
  • Global variables defined in a central location.
• Enumerations
  • Example: (user-defined) { INITIAL, WAITING, WORKING, DONE }
  • Global enumeration defined in central location.

Supported Operations

• Booleans
  • Compare (equals, not equals)
  • Binary operations (and, or, xor, implies)
  • Unary operations (not)
  • Assignment
• Integers
  • Compare (equals, not equals, greater than, less than, greater or equal to, less or equal to)
  • Binary operations (addition, substraction, multiplication, we do not support division)
  • Unary operations (additive complemettn (-VarName) : (we do not support (pre/post)-increment, (pre/post)-decrement)
  • Assignment
• Enumerations
  • Compare (equals, not equals)
    • DA: Ok, no < or > (no ranking)
  • Assignment

BNF Grammar for conditions used in jUCMNav

• Spacing added for readability
• Limitations of BNF grammar:
  1. The grammar as expressed requires a type-checker working above it.

Expression              := Implication
Implication             := Disjunction (Implies Disjunction)*
Disjunction             := Conjunction ((Or | Xor ) Conjunction)*
Conjunction             := Comparison (And Comparison)*
Comparison              := BooleanUnit ((Equals| NotEquals) BooleanUnit)*
Negation                := Not BooleanUnit
BooleanUnit             := Negation | RelationalExpression | BooleanConstant 
RelationalExpression    := AdditiveExpression ((GreaterThan | GreaterOrEqualTo | LowerThan | LowerOrEqualTo) AdditiveExpression)?
AdditiveExpression      := MultiplicativeExpression ((Addition | Substraction) MultiplicativeExpression)*
MultiplicativeExpression:= UnaryExpression (Multiplication UnaryExpression)*
UnaryExpression         := (Addition | Substraction)? ("(" Expression ")" | IntegerConstant | Identifier )

And                     := "and" | "&&"
Or                      := "or" | "||"
Xor                     := "xor" | "^"
Implies                 := "=>"
Equals                  := "=" | "=="
NotEquals               := "not" | "!"
GreaterThan             := ">"
GreaterOrEqualTo        := ">="
LowerThan               := "<"
LowerOrEqualTo          := "<="
Addition                := "+"
Substraction            := "-"
Multiplication          := "*"
IntegerConstant         := ["0"-"9"]+
BooleanConstant         := "true" | "false"
Identifier              := ["_","a"-"z","A"-"Z"](["_","a"-"z","A"-"Z", "0"-"9"])*

BNF Grammar for operations in responsibilities

ResponsibilityAction   := Statement+
Statement              := Assignment | CompoundStatement  | IfStatement
Assignment             := Identifier AssignmentOperator Expression StatementTerminator
CompoundStatement      := "{" Statement* "}"
IfStatement            := If Expression Statement (Else Statement)?

AssignmentOperator     := "=" | ":="
If                     := "if"
Else                   := "else"
StatementTerminator    := ";"

BNF Grammar for global definitions

• None. These will be constrained by UI.

Type-checker rules.

• (Boolean) Implies (Boolean) : (Boolean)
• (Boolean) Or (Boolean) : (Boolean)
• (Boolean) Xor (Boolean) : (Boolean)
• (Boolean) And (Boolean) : (Boolean)
• (Boolean) Equals (Boolean) : (Boolean)
• (Boolean) NotEquals (Boolean) : (Boolean)
• (Integer) Equals (Integer) : (Boolean)
• (Integer) NotEquals (Integer) : (Boolean)
• (EnumerationName) Equals (EnumerationName) : (Boolean)
• (EnumerationName) NotEquals (EnumerationName) : (Boolean)
• Not (Boolean) : (Boolean)
• (Integer) GreaterThan (Integer) : (Boolean)
• (Integer) GreaterOrEqualTo (Integer) : (Boolean)
• (Integer) LowerThan (Integer) : (Boolean)
• (Integer) LowerOrEqualTo (Integer) : (Boolean)
• (Integer) Addition (Integer) : (Integer)
• (Integer) Substraction (Integer) : (Integer)
• (Integer) Multiplication (Integer) : (Integer)
• ( (Boolean) ) : (Boolean)
• ( (Integer) ) : (Integer)
• ( (EnumerationName) ) : (EnumerationName)
• Substraction (Integer) : (Integer)
• Addition (Integer) : (Integer)
• If (Boolean) (void) : (void)
• If (Boolean) (void) Else (void) : (void)
• (Boolean) AssignmentOperator (Boolean) : (void)
• (Integer) AssignmentOperator (Integer) : (void)
• (EnumerationName) AssignmentOperator (EnumerationName) : (void)
• { (void) } : (void)

Later iterations

• To be implemented when scenarios work with the core data model according to re-evaluated needs.
• If required, support real numbers and include support for multiplication and division.
• If desired, support loops.
• If desired, functions.
• Arrays, more complex data structures.
• DA: What about errors created by the underlying (Java) data types used (e.g., overflow)?
  • JK: Dynamic aspects (exceptions) will be handled at runtime.

Changes to metamodel

• Add expression property to Responsibility (definition)
• Remove link between UCMspec and Scenario Def?.
• Create recursive link between Scenario Def? and itself for included scenarios (0...*).
• Make Scenario Def? included in at most one Scenario Group? instead of 1...*
• Remove link between Variable and Condition.
• Add class Enumeration Type? extends UCMmodel Element? (to be similar to Variable)
  • string name (already in URNmodel Element?)
  • string description (already in URNmodel Element?)
  • string [] values
• Composition Enumeration Type? inside UCMspec (as with Variable) (1 to 0...*)
• Link from Variable to Enumeration Type? (1 Variable to 0...1 Enumeration Types?)
• Link from Scendario Def? to Start Point? should be bidirectional.
• Link from Scenario Def? to End Point? (0...*) (similar to link to Start Points?, but optional)
• Link from Scenario Def? to Condition (0...*) named Preconditions
• Link from Scenario Def? to Condition (0...*) named Postconditions
• Add class Initializations
  • string value
• Link from Scenario Def? to Initializations (1 to 0...*)
• Link from Initializations to Variables (1 to 1)
• Scenario Def? should not be abstract.
• Add Metadata class for URNmodel Element? annotations

-- Jason Kealey - 12 May 2006