1. 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.

2. Contents Problem Statement System Structure Two-Level Grammar (TLG) Case Study – ATM Example Conclusion Objectives Motivation Approach Natural Language Processing Knowledge Base Non-Functional Aspect (QoS) 2

3. Problem Statement 3 Functional aspectNon-functional aspect Well defined domain (concrete)Abstract and non-quantifiable Local and simple attributes correlationDynamic and complex correlation Easy prototyping and verificationPoor measurement and formalism Users’ main interestIts 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

4. Objectives Formal specification of QoS Decomposability of QoS attributes 4 Correlation among QoS actions QoS specifications in natural language User friendly interface Reuse of requirements document Two-level Grammar (TLG) Natural Language Processing (NLP)

5. System Structure 5

6. Non-functional Aspect (QoS) QoS attributes Features or parameters of QoS 6 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 QoS actions Events that have affect on QoS attributes Correlation Decomposition QoS properties Constraints on QoS actions

7. Natural Language Processing 7

8. Natural Language Processing (Cont’d) 8

9. Knowledge Base Tree-like structure Composed of Linguistics information – parts of speech Contextual information – relations between sentences Example 9

10. Syntax Properties Natural-language-like syntax Flexibility Formal notation Formalism Object-oriented structure Abstraction Logic/Functional operation Computation Two-Level Grammar (TLG) class Class_Name. Data_Name {, Data_Name} :: Data_Type {, Data_Type}. Rule_Name : Rule_Body {, Rule_Body} {; Rule_Body}. end class. 10

11. 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. 11

12. 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%. 12

13. ATM – QoS Requirements in XML 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 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% 13

14. ATM - Knowledge Base 14

15. 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 > 10000, User_Timeout < 120000. update level : Response_Time > 30000, Level := 40. end class. 15

16. ATM – Two-Level Grammar (cont’d) class ATM_Security extends Property. Maximum_Allowed_Attempts :: Integer. Encryption_Byte_Length :: Integer. Allowed_Attempts :: Integer. Account_Type :: String. check satisfaction : Encryption_Byte_Length > 3, Allowed_Attempts < Maximum_Allowed_Attempts. update level : Encryption_Byte_Length = 6, Allowed_Attempts < 5, Level := 80. update attributes : Account_Type = "savings", Maximum_Allowed_Attempts := 4; Bank_Capacity Maximum_Connections < 50, Maximum_Allowed_Attempts := 4; ATM_Delay Level < 50, Maximum_Allowed_Attempts := 4. end class. 16

17. ATM - Unified Modeling Language (UML) 17

18. Conclusion 18 Summary Formal specification of QoS using TLG QoS specifications in natural language using NLP Express the constraints in Object Constraint Language (OCL) Future Work Combine Model Driven Architecture (MDA) and formal methods in representing the QoS properties, and implement the representation within MDA

19. THE END Beum-Seuk Lee : leebs@cis.uab.edu www.cis.uab.edu/info/grads/leebs UniFrame : www.cs.iupui.edu/uniFrame Contact info :