40 1 Abstract— The motivation of this paper is to enhance system development efficiency by integrating system modeling methods and system scale measurement methods. Among system modeling methods, FPM (Function Point Method) has been attracting a lot of attention. In this paper, we first propose a method to measure function points from specifications written with a widely used formal specification language VDM-SL (Vienna Development Method- Specification Language). Then the development of an automatic measurement tool based on this method is introduced. Finally, to demonstrate the effectiveness of our method, measurement of a sample case using the proposed method is examined and discussed. Index Terms— Software development, Specification languages I. INTRODUCTION ECENTLY, the concept of highly dependable or highly reliable systems is attracting attention in service management field. Especially, current network based information systems become large scale and complicated, consequently there is a possibility to have a serious damage in social life when we have a failure in such a system. While Project delay and budget overrun has been a significant problem in software projects. What can we do to develop software and sell it at proper price for its functions? Firstly, we need to model the system to reflect the demand of users correctly; secondly, we must measure the size of the system precisely to estimate the period, cost, and so on. The purpose of this paper is to enhance information system development efficiency by integrating modeling methods and system scale measurement methods. Concretely, we try to devise the measurement method of Function Point (FP hereafter) with VDM-SL (Vienna Development Method Specification Language) specifications. An automatic measurement tool is also developed based on the proposed method. By applying implemented automatic measurement tool to a sample case, advantages and problems of the tool are examined. Manuscript received December 1, 2007. Tomoko Miyawaki is a Master Candidate at the Graduate School of Decision Science and Technology, Tokyo Institute of Technology (e-mail: miyawaki.t.aa@m.titech.ac.jp). Junichi Iijima is a professor with Graduate School of Decision Science and Technology, Tokyo Institute of Technology (phone: +81-3-5734-3942; fax: +81-3-5734-3942; e-mail: iijima.j.aa@m.titech.ac.jp). Sho Ho is an assistant professor with Graduate School of Decision Science and Technology, Tokyo Institute of Technology (ho.s.aa@m.titech.ac.jp). II. BACKGROUND AND RELATED WORKS A. Overview of Function Point FP is one of the ways to measure the size of software, proposed by Allan J. Albrecht over 30 years ago[1]. Later, in 1986, IFPUG (International Function Point Users Group)[2] was founded. The guideline for FP method formulated by IFPUG is called IFPUG rule and is adopted as an ISO standard [3]. The IFPUG rule has become a de-facto standard for FP method today. In this research, FP is counted following IFPUG rule. In FPM, functions are identified and enumerated based on the requirement definition from the user's viewpoint. Number of functions is counted to measure the size of the system [4]. As shown in Fig.1, basically, functions counted in FPM can be divided into two types: data function (DF) type and transaction function (TF) type. Data function type is determined from Internal Logical Files (ILF) and External Interface Files (EIF); Transaction Function type is determined from External Inputs (EI), External Outputs (EO) and External Queries (EQ). Once ILF, EIF, EI, EO and EQ items are enumerated, each item is assigned a subjective “simplicity” rating on a three-point ordinal scale: “simple,” “average,” or “complex.” [5] The rating is based upon DET’s (Data Element Type), RET’s (Record Element Type) and FTR’s (File Type Referenced). A DET is a unique user recognizable, non-recursive field which is dynamic. Elements such as calculated values and confirmation messages are counted as DET; An RET is a user recognizable sub group of data elements within an ILF or an EIF; An FTR is a file type referenced by a transaction. An FTR must also be an ILF or an EI [6]. After rating all ILF, EIF, EI, EO and EQ items, a weight is assigned to each item according to its type and its “simplicity” Measuring Function Points from VDM-SL Specifications Tomoko Miyawaki, Junichi Iijima and Sho Ho R Internal Logical File (ILF) External Interface File (EIF) Not Measured Application Measured Application External Input (EI) External Output (EO) External Inquiry (EQ) User Fig.1. Five items of FP