Measuring Function Points from VDM-SL Specifications

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1 Measuring Function Points from VDM-SL Specifications Tomoko Miyawaki, Junichi Iijima, Sho Ho 宮脇智子飯島淳一包捷 Department of Industrial Engineering and Management Graduate School of Decision Science and Technology Tokyo Institute of Technology, Tokyo, JAPAN 1

2 Contents 1. Introduction 2. Background and Literature Survey I. Overview of Function Point II. Overview of VDM-SL III. Literature Survey 3. Rules for Measuring FP 4. FP Calculation Tool for VDM-SL 5. Case Study 6. Conclusion and Future Research 2

3 Introduction How can we realize highly dependable or highly reliable systems? System modeling VDM is one of the approach to reflect the requirement of users correctly and to realize highly dependable system. Measuring the system size Function Point Analysis (FPA, hereafter) is widely used method to measure software size. 3

4 Purpose of this research The purpose is to propose an efficient system development methodology by putting modeling method and measuring size method simultaneously. Concretely, to try to devise the method for measuring Function Point (FP, hereafter) from VDM-SL specifications. 4

5 Overview of FP Method One of the methods to measure the size of software It is a method to assign points to files and data processes in the software according to the complexity. 5

6 Five Components of FPs User 1External Input (EI) Application In concern Application Out of concern 2 External Output (EO) 3 External Inquiry (EQ) 4Internal Logical File (ILF) 5External Interface File (EIF) Transaction Function The function realized by data process Assign Points based on complexity by DET & FTR Data Element Type File Type Reference Data Function The function recognized as file Assign Points based on complexity in DET & RET Record Element Type 6

7 Overview of VDM-SL VDM-SL : Vienna Development Method Specification Language We can analyze a specification described in VDM-SL easily with VDMTools. Model checking Test Cases IC card system Air traffic control system VDMTools 7

8 Literature Survey Measuring FP from ER-DFD [Gramantieri et al. 1997] Measure FP from visually described specifications Measuring FP from B Specifications [Diab et al. 2002] Measure FP from Specification Language. Judgment of Complexity is ambiguous in this method. Entity ER-DFD Relationship Process Entity External Agent 8

9 Seven steps for measuring FP 1Find data function from type definition. 2Measure DET & RET of data function. 3Find transaction function from function definition and decide EI, EO, and EQ. 4Determine ILF & EIF from data function. 5Measure DET & FTR in transaction function. 6Assign points based on complexity for each function. 7Sum up all functions FP. Unadjusted Function Point UFP 9

10 The Structure of VDM-SL VDM-SL Specification Block to abstract the data structure. Data Definition Data functions (ILF,EIF) are distinguished in this block. Block to abstract the algorithm. Function Definition Transaction functions (EI,EO,EQ) are distinguished in this block. 10

11 Data Definition Block VDM-SL Specification Basic type Complex type Mapping type 11

12 Mapping Type VDM-SL Specification Ms. A Mapping type Name pinfo pinfo Ms. A Mr. B Mr. B Ms. C Ms. C AUS AUS AUS JPN JPN Mapping type Find the data function from the mapping type which connects data logically. 12

13 Function Definition Block VDM-SL Specification Function s Name Signature Post-condition Formula 13

14 Function Definition Block VDM-SL Specification Signature Type of Input Type of Output Determine the type of transaction function from the signature which shows the types of the function s in/output. 14

15 Notation Z:VDM-SL Specification of application whose FP is to be measured. Btypes : the set of basic data types ={nat, nat1, int, real, bool, char, token} types(z): the set of types defined in Z functions(z): the set of functions defined in Z 15

16 Notation - Element Functions Element Functions S is product type and S = S 0 * S (S 0 is not product type): element( S * 0 S ) = element( S0 ) element( S ) S is complex type: element ( S) = element( T1 ) L element( T n ) complex type: S :: e S is another type: e 1 2 : T 1 : T 2 M e n : T n ( S) { S} element = 16

17 Notation - Data Function Data Function ( S ) = { m m types( Ζ) ( T types( Ζ) )( m map S tot )} DF = Complexity for RET for S S DET DF( Ζ), ( S ) = { U U types( Ζ) ( T types( Ζ) )( U = map S tot )} DF( Ζ), ( S ) = element( S ) U{ element( T ) ( U RET( S ))( U = map S tot )} 17

18 Notation - In/Output Data Set For function for Signature F : Input Data Set: ids X Output Data Set: ods L functions functions For mapping type X Y L Y 1 m 1 n, for mapping type Input Data Set: ids Output Data Set: ods ( F ) = element( X 1 ) L element( X m ) ( F ) = element( Y ) L element( Y ) M : map S tot, types 1 ( F ) = element( S ) ( F ) = element( T ) types m 18

19 Notation - Transaction Function External Input ( Ζ) = { F F functions( Ζ) ( S types( Ζ) )( U RET ( S )) (( ids( U ) ods( U )) ids( F ) φ DF( S ) ids( F ) ods( F ) φ)} EI External Output EO ( Ζ) = { F F functions( Ζ) ods ( F ) Btypes φ} External Inquiry ( Ζ) { F F functions( Ζ) ( S DF( Ζ) )( U RET( S ))( V ids( U ) ods( U )) ( U ids( F ) ( V ods( F ) set( seq) of V ods( F )))} EQ = 19

20 Notation - Transaction Function Complexity FTR ( F ) = { S F functions( Ζ) ( U RET ( S ))( U ids( F ))} DET ( F ) = { T F functions ( Ζ) ( T types( Ζ) Btypes )( T ( ids( F ) ods( F )) DET ( S ))} 20

21 Counting DET from Other Part VDM-SL Specification 6 DETs functions ShowPresent : Member_id * RequestBook * Book * Store * Member -> set of (Isbn * Title * Name * Member_id * Name * Date) * Emessage] ShowPresent (id, rbook, bbook, sbook, mbook) == mk_({mk_(rbook.request(r).isbn, bbook(rbook.request(r).isbn).title, sbook(rbook.present(r).present_store_id).name, rbook.request(r).member_id, Except Signature mbook(rbook.request(r).member_id).minfo.name, rbook.present(r).date_before_present) r : Seq_request_id & rbook.present(r).present_member_id = id}, nil); 7 DETs 21

22 Measuring FP Count one data function for each set of mapping types which have a common domain. Count one transaction function for each function in the specification. Assign points based on complexity and measure UFP Function Complexity low middle high Internal Logical File (ILF) External Interface File (EIF) External Input (EI) External Output (EO) External Inquiry (EQ)

23 FP Calculation Tool for VDM-SL FP calculation tool reads a VDM-SL specification and measure FP automatically using the proposed method. As a result, calculated FPs for several specifications were correctly measured. The result of Measuring FP System 23

24 Case Study Target : Asase Book Store Online Order System Project Online members can order books on the Web, and clerks can manage order and members information. Asase Book Store System 24

25 The Process of Measuring Requirement Definition types Table Definition Documents Screen Contents Definition Measure directly Compare VDM-SL Specification UFP Measure from VDM-SL Specification 25

26 Result (bench mark in parentheses) 識別不能なファンクション Functions which have two kinds Different kind of function 26

27 Reasons of different results from bench mark Functions which have two kinds These specifications are written from the viewpoint of not users but system developers. We have to chose proper type as users. Different kind of function Details have not decided. 27

28 Advantages of this method We can measure FP without any document except specification. Complexity, especially RET & FTR, can be assigned clearly, though ambiguously in the methods of literature survey. 28

29 Conclusion A method to measure FP from VDM-SL Specifications is proposed. The advantage of this method is its ability of measuring the degree of complexity of functions The followings are achieved with this measuring method. Development of calculation tool Consideration of this method by case study 29

30 Future works Enhancement of measuring method Apply the proposed method for other practical VDM-SL Specifications. Calculation tool for FP Generation of FPA report Connection with VDM-SL Tool Visualization of ambiguities 30

31 Thank You for Your Attention. 31

Measuring Function Points from VDM-SL Specifications

40 1 Measuring Function Points from VDM-SL Specifications Tomoko Miyawaki, Junichi Iijima and Sho Ho Abstract The motivation of this paper is to enhance system development efficiency by integrating system