Formal Specification of Non-Functional Aspects

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Formal Specification of Non-Functional Aspects
in Two-Level Grammar
Chunmin Yang, Beum-Seuk Lee, Barrett Bryant,
Carol Burt University of Alabama at
Birmingham Rajeev Raje Indiana University
Purdue University Indianapolis Mikhail Auguston
Andrew Olson New Mexico State University
This research is based upon work supported by, or
in part by, the U. S. Army Research Laboratory
and the U.S. Army Research Office under
contract/grant number DAAD19-00-1-0350 and by the
U. S. Office of Naval Research under award number
N00014-01-1-0746.
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Contents
Motivation
Problem Statement
Objectives
Approach
System Structure
Non-Functional Aspect (QoS)
Natural Language Processing
Knowledge Base
Two-Level Grammar (TLG)
Case Study ATM Example
Conclusion
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Problem Statement
Functional aspect Non-functional aspect
Well defined domain (concrete) Abstract and non-quantifiable
Local and simple attributes correlation Dynamic and complex correlation
Easy prototyping and verification Poor measurement and formalism
Users main interest Its importance neglected
the system should sort the list of the given numbers the system should maintain high level of security
Non-functional aspect (Quality of Service - QoS)
in the UniFrame project
Query of heterogeneous components that satisfy
certain QoS
QoS specification and management
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Objectives
Formal specification of QoS
Decomposability of QoS attributes
Correlation among QoS actions
Two-level Grammar (TLG)
QoS specifications in natural language
User friendly interface
Reuse of requirements document
Natural Language Processing (NLP)
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System Structure
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Non-functional Aspect (QoS)
QoS attributes
Features or parameters of QoS
QoS catalog throughput, capacity, end-to-end
delay, parallelism constraints, availability,
ordering constraints, error rate, security,
transmission, adaptivity, evolvability,
reliability, stability, result, achievability,
priority, compatibility, and presentation
Decomposition
QoS actions
Events that have affect on QoS attributes
Correlation
QoS properties
Constraints on QoS actions
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Natural Language Processing
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Natural Language Processing (Contd)
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Knowledge Base
Composed of
Linguistics information parts of speech
Contextual information relations between
sentences
Tree-like structure
Example
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Two-Level Grammar (TLG)
Syntax
class Class_Name. Data_Name , Data_Name
Data_Type , Data_Type. Rule_Name Rule_Body
, Rule_Body Rule_Body. end class.
Properties
Natural-language-like syntax Flexibility
Formal notation Formalism
Object-oriented structure Abstraction
Logic/Functional operation Computation
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Two-Level Grammar - Example
class Palindrome. Char Character. Str
Char. Empty is a palindrome. Char is
a palindrome. Char Str Char is a palindrome
Str is a palindrome. end class.
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ATM QoS Requirements Document in NL
ATM's security property is as follows. The
length of the encryption byte should be bigger
than 3 and the allowed attempts has to be smaller
than the maximum allowed attempts. If the
encryption byte length is 6 and the maximum
allowed attempts is less than 5 then the system
is 80 secure. If the account type is a savings
account or the maximum allowed connections of the
bank is less than 50 or the delay level is less
than 50 then the maximum allowed attempts is
limited to 4. If the user timeout is between
10000 and 120000 milliseconds we have a good
delay level. If the response time is longer
than 30000 milliseconds, the delay level drops
down to 40.
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ATM QoS Requirements in XML
ltc title "ATM"gt ltc title "Security"gt ltp
meta "satisfaction check"gt ltsgtThe length
of the encryption byte should be bigger than 3
and the allowed attempts has to be smaller
than the maximum allowed attemptslt/sgt lt/pgt ltp
meta "level update"gt ltsgtIf the encryption
byte length is 6 and the allowed attempts is less
than 5 then the system is 80 securelt/sgt
lt/pgt ltp meta "attribute update"gt
ltsgtIf the account type is a savings account or
the maximum allowed connections of the
bank is less than 50 or the delay level is less
than 50 then the maximum allowed attempts
is limited to 4lt/sgt lt/pgt lt/cgt ltc title
"Delay"gt ltp meta "satisfaction check"gt
ltsgtIf the user timeout is between 10000 and
120000 milliseconds we have a good delay
levellt/sgt lt/pgt ltp meta "level update"gt
ltsgtIf the response time is longer than 30000
milliseconds the delay level drops down to
40lt/sgt lt/pgt lt/cgt lt/cgt
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ATM - Knowledge Base
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ATM Two-Level Grammar (TLG)
class Property. Level int. end class. class
Bank_Capacity extends Property.
Maximum_Connections Integer. end class. class
ATM_Delay extends Property. Response_Time
Integer. User_Timeout Integer. check
satisfaction User_Timeout gt 10000,
User_Timeout lt 120000. update level
Response_Time gt 30000, Level 40. end class.
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ATM Two-Level Grammar (contd)
class ATM_Security extends Property.
Maximum_Allowed_Attempts Integer.
Encryption_Byte_Length Integer.
Allowed_Attempts Integer. Account_Type
String. check satisfaction
Encryption_Byte_Length gt 3, Allowed_Attempts lt
Maximum_Allowed_Attempts. update level
Encryption_Byte_Length 6, Allowed_Attempts lt 5,
Level 80. update attributes
Account_Type "savings", Maximum_Allowed_Attempts
4 Bank_Capacity Maximum_Connections lt
50, Maximum_Allowed_Attempts 4 ATM_Delay
Level lt 50, Maximum_Allowed_Attempts 4. end
class.
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ATM - Unified Modeling Language (UML)
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Conclusion
Summary
Formal specification of QoS using TLG
QoS specifications in natural language using NLP
Future Work
Express the constraints in Object Constraint
Language (OCL)
Combine Model Driven Architecture (MDA) and
formal methods in representing the QoS
properties, and implement the representation
within MDA
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THE END
Contact info
Beum-Seuk Lee leebs_at_cis.uab.edu
www.cis.uab.edu/info/grads/l
eebs UniFrame
www.cs.iupui.edu/uniFrame