A Comparative Analysis of Formal languages Based upon Various Parameters Javeria Jabeen MS(CS) Student,UIIT PMAS Arid Agriculture University Rawalpindi, Pakistan Mateen Ahmed Abbasi MS(CS) Student,UIIT PMAS Arid Agriculture University Rawalpindi, Pakistan Nasir Mehmood Minhas Assistant Professor, UIIT PMAS Arid Agriculture University Rawalpindi, Pakistan Abstract-Formal method is collection of mathematics notations addressing the requirement specification, analysis and verification at any stage of the system life-cycle. Formal method identifies bugs or error in early stage of development. At the end product is delivered as per user requirement. Due to this reason many critical control systems are developed using formal methods. Formal method play silver built role in the software industry. Model based languages are Z, B and VDM are popular formal specification languages and mostly used in the industry. In this paper we compare three formal specification languages Z, B and VDM based upon various factor. The factors use for comparison is specification style, writing specification structure, support for object orientation, tool support, cost and Quality, Concurrency, Code generation, industrial application and domain. Keywords- Formal specification language; Schema I. INTRODUCTION Software engineering main focus is to develop the quality product/system. It is only possible when specification of the system is complete, correct and consistent. Formal specification is better way of identifying specification errors and describing system specification in unambiguous way. Formal specification language expressed the specification in a language whose vocabulary syntax and semantic are properly defined. Formal specification language provides mathematical representation of the system. Using formal method bugs find early and cost and time phase decreases in verification and testing phase. Quality of the product improves using formal method[1]. We present formal specification language its advantages and disadvantages in 2 nd Section. In 3 rd Section, Z, B and VDM are examinedon base of aspects such as specification style, writing specification structure, support for object orientation, tool support, cost and Quality, industrial application and domain. Discussion is described in section 4. Conclusions are presented in Section 5. II. FORMAL SPECIFICATION LANGUAGES Formal Technique is mathematical model which is used to specify hardware and software of the system, verify the specification of the system and characteristics of the system. Formal method is applied during the development phase because it ensures that system is complete, correct and consistent specification.Formal specification language provides mathematical representation of the system. A formal language is collection of syntax, semantics and its relations.Semantics use to define “Universe of Object” .objects help foe defining the system. Relation defines the rule that indicate which objects satisfy the system specification[2]. Advantages and limitations: Formal specification languages have many advantages which are discuss below.  Specifications are correct, complete and consistent.  A formal method is automatic verification of specification.  Specifications are non-Ambiguous.  Quality of the product is improved.[2] Limitations of formal method:  Customer can‟t easily understand the specification.  Difficult to learns and use the formal method.  Lack of tools support available for formal method.[3] III. COMPARISON In this section we do comparison of the Z, B and VDM on the basis of the different parameters. A. Specification Style There are many styles exists for writing specification. Model based languages are Z, B and VDM. Z language describes system abstractly and it is based on mathematics. Z notation is not executable. B language is the combination of Abstract machine notation (AMN) and process of obtaining implementation form abstract model by stepwise refinement. Machine is directly translated into code. Compared to the B, Z is higher level language. Z, B, VDM all languages use set theory and logics. Vienna Development Method comprises a specification language and an approach to refining specifications into code. 434 Vol. 3 Issue 3, March - 2014 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 www.ijert.org IJERTV3IS030511