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Deriving Operational Software Specification from System
Goals
Xin BaiEEL 5881 Course
Fall, 2003
Reference Paper
“Deriving Operational Software Specification from System Goals” November 2002, Proceedings of the tenth
ACM SIGSOFT symposium on Foundations of software engineering
Content
Introduction Goal-Oriented Elaboration of Require
ments Semantics of Operationalization Operationalization Patterns Analysis
Introduction Lots of techniques and tools for
specification analysis Algorithmic model checking, Deductive
verification etc. Building formal specifications for
complex software is not easy Translate natural language statements to
some formal language To be elaborated, structured, interrelated
and negotiated
Introduction
Goal-oriented requirements engineering The use of goals for requirements
elicitation, elaboration, organization, specification, analysis, negotiation, assignment, documentation and evolution.
Introduction
Goals Objectives the system under consideratio
n must achieve E.g. “safe transportation” and “reverse th
rust enabled when wheels pulse on” Achieving goals require the cooperation
of multiple agents (humans, devices or software)
Introduction
Goal refinement To decompose a goal into subgoals so th
at each subgoal requires the cooperation of fewer agents
Stops when goals can be assigned as responsibility of single agents
Goal-oriented elaboration of requirements An application model is composed of f
our submodels: Goal model Object model Agent model Operation model
The goal model The various objectives the system
should meet are defined in this model
The goal model
Temporal operators
The goal model
The goal model A sample
The object model
Defines the domain entities, relationships and attributes
A sample
The agent model
Defines the responsibilities and interfaces of the various agents
A sample
The operation model Defines the various services to be provided
by agents Domain pre/post conditions
Capture the elementary state transitions defined by operation applications in the domain
Required pre/post/trigger conditions Capture additional strengthenings to ensure tha
t the goals are met
The operation model A required preconditions
Captures a permission to perform the operation when the condition is true
A required trigger condition Captures an obligation to perform the operation
when the condition becomes true provided the domain precondition is true
A required postcondition Captures an additional condition that must hold
after any application of the operation
The operation model Difference between domain and
required conditions Domain conditions describe what an
application of the operation means in the domain without any prescription as to when the operation must be applied and when it may not be applied.
The operation model A sample for domain conditions
The operation model A sample for required conditions
Semantics of operationalization Functional goals need to be operation
alized into specifications of services the agents should provide to meet them
Operationalization is a process that maps declarative property specifications to operational specifications satisfying them
Semantics of operationalization It takes the form of a set of
operations specified by domain and required pre, post- and trigger conditions.
Semantics of operationalization Correctness of goal operationalizatio
n Completeness Consistency minimality
Operationalization patterns A pattern-based technique for operati
onalizing goals, specified in real-time linear temporal logic (RT-LTL), into operations specified by pre-, post- and trigger conditions
Operationalization patterns An operationalization pattern is an ab
stract AND-operationalization link between a goal specification pattern in RT-LTL and a set of required pre-, trigger and postcondition specification patterns that operationalize the root correctly.
Operationalization patterns The Immediate Achieve pattern
Operationalization patterns The Bounded Achieve pattern
Operationalization patterns The “InBetween” Invariance patter
n
A taxonomy of goal patterns
Operationalization patterns In every but very rare cases, the
goals match one of the general patterns in the previous taxonomy diagram
Not complete, could be enriched with additional goal patterns
Analysis
Benefits Abstraction from formal details Completeness assurance Guidance in writing operational
specifications Goal mining from operational
specifications
Thank you!