Ranjan Dasgupta

Use of Semi-Formal and Formal Methods in Requirement Engineering of ILMS

A systematic approach in requirement engineering helps in discovering and understanding the requirements at different levels of abstraction as well as makes the requirements traceable and verifiable early in the project. This paper presents a methodology for requirement engineering by using a combination of formal and semiformal techniques to model software requirements for analysis and verification. The proposed framework incorporates requirement-analysis and requirement-verification models, which are guided by the Domain Model represented by a Conceptual Class diagram and the defined Ontology. The proposed approach is particularly useful when requirements are defined in hierarchical levels of abstraction and traceability between a requirement at a detailed level and its correspondence at an abstract level is required. The proposed framework also allows verification of the accordance of the requirements with respect to the Domain Model. The requirement analysis model at each level of abstraction is represented by a combination of three different modeling techniques: Conceptual Graph, Use-Case diagram and VDM-SL specification. A verification model to ensure traceability between the requirements at different abstraction levels, using a three-dimensional schema, is also proposed. The Requirements of an Intelligent Learning Management System are used as an example to illustrate the proposal.

INTEGRATION OF FUNCTIONAL AND INTERFACE REQUIREMENTS OF AN WEB BASED SOFTWARE: A VDM BASED FORMAL APPROACH

Analysing user requirements properly is the key to any software development process. In contemporary web based software developments the user interface requirements are predominant among the non functional requirements. The end-users’ involvement in interface requirements has made it challenging for the designers to map these interface requirements with functional requirements. As a consequence we often use different specification languages for different types of requirements but then interface requirements, if handled separately May lead to traceability problem for the developers, especially in web based application development. In order to make requirements analysis both comprehensible and rigorous, formal requirements specification methods are very important. In this paper we have tried to describe how interface requirements can be specified in a formal way in connection with the functional requirements for a better understanding in designing. The Vienna Development Method Specification Language (VDM-SL) being a well established formalizing tool for user requirements specification, we propose some add-ons to this tool to help in formalizing these types of requirements. We have also used this technique in a case study to strengthen our proposal.

Architectural design of a LMS with LTSA-conformance

This paper illustrates an approach for architectural design of a Learning Management System (LMS), which is verifiable against the Learning Technology System Architecture (LTSA) conformance rules. We introduce a new method for software architectural design that extends the Unified Modeling Language (UML) component diagram with the formal architectural style of Acme, hence, combines the advantages of the visual appeal of a graphical method and preciseness of a formal method. We propose some new stereotypes for UML component-connector style to incorporate Acme style within UML. A UML meta-model for the design components is also proposed to elucidate the relationships between the components. We also propose a verification method to ensure that the design artifact is holding conformance with LTSA standard. The design process as well as the verification process entails additional knowledge about the domain, which is supplied by the domain Ontology. The LTSA conformance rules, written in natural language, are represented more formally with help of Conceptual Graph representation, before using them in the verification process. Finally, we introduce a verification method that tries to find out a design pattern in the architectural design that conforms to the particular conformance rule intended to check. The verification process also introduces a goodness measure of the conformance.

Engineering of requirements for a distributed teleteaching system: a conceptual graph-based approach

This work proposes a graph based requirement analysis approach and its verification methodology to address the challenges of requirements engineering in the context of a distributed teleteaching system. Requirements are generally expressed in natural language and in the absence or limited use of the requirements elicitation phase, verification of requirements and traceability of requirements to different artifacts of the subsequent phases becomes difficult. In this work we use i* diagrams, the well known standard for agent based requirements analysis. Then we propose Extended Means Ends Analysis (EMEA) with the addition of some new constructs. Next we define a transformation algorithm to derive a conceptual graph (CG) and propose a method for conceptual graph based requirements specification and its verification. A metrics based evaluation for performance measurement of the proposed method in terms of requirements traceability is presented.

LTSA conformance testing to architectural design of LMS using ontology

This paper proposes a new methodology for checking conformance of the software architectural design of Learning Management System (LMS) to Learning Technology System Architecture (LTSA). In our approach, the architectural designing of LMS follows the formal modeling style of Acme. An ontology is built to represent the LTSA rules and the software architecture in Acme style. Conformity of the design with LTSA rules is tested by reasoning the ontology with the query language SPARQL. A Java-based plug-in system is introduced to implement functionalities like loading the elements of the architectural design into the ontology, mapping the architectural elements with LTSA elements, and performing the conformance test. The advantage of the proposed methodology is two-folded. First, it verifies an important software quality attribute – conformance to technical standard – at an early stage of development, like high-level design phase. Secondly, instead of the conventional manual checklist based approach of conformance testing, this methodology focuses on an automated way to finding the conformance level of the system under check.

Using Semiformal and Formal Methods in Software Design: An Integrated Approach for Intelligent Learning Management System

The use of graphical methods such as unified modelling language (UML) in conjunction with formal methods such as Vienna development method (VDM) can be significantly beneficiary in the software design phase due to their complimentary features. UML diagrams are very useful in communication among different stakeholders, but at the same time, being semiformal in nature, they lack formal syntax and preciseness due to textual description in notations. This makes it challenging to verify the design against the requirements. Conversely, a formal specification language like VDM-SL has the advantage of preciseness an unambiguous modelling, but unable to provide ease of understanding like UML. This paper presents a methodology that integrates the use of UML and VDM-SL in software design phase and also proposes a verification technique for the design artefacts with the requirements. A case study of intelligent learning management system (ILMS) is used in this paper to illustrate the proposed work.