State-based versus event-based specifications for information systems: a comparison of B and eb3

Abstract

This paper compares two formal methods, B and eb 3 , for specifying information systems. These two methods are chosen as examples of the state-based paradigm and the event-based paradigm, respectively. The paper considers four viewpoints: functional behavior expression, validation, verification, and evolution. Issues in expressing event ordering constraints, data integrity constraints, and modularity are thereby considered. A simple case study is used to illustrate the comparison, namely, a library management system. Two equivalent specifications are presented using each method. The paper concludes that B and eb 3 are complementary. The former is better at expressing complex ordering and static data integrity constraints, whereas the latter provides a simpler, modular, explicit representation of dynamic constraints that are closer to the user's point of view, while providing loosely coupled definitions of data attributes. The generality of these results from the state-based paradigm and the event-based paradigm perspective are discussed.

How to Synthesize Relational Database Transactions From EB3 Attribute Definitions?

“…Several papers deal with the synthesis of relational implementations. Most of the time, refinement techniques are used, like in [2] for Z and [11] for B specifications, which are orthogonal in specification style to EB 3 [4].…”

“…The complete syntax and semantics of EB 3 can be found in [6] and the process expression for the example in [8]. EB 3 expressions are close to the user view and complex constraints inside and between entities are easy to specify in EB 3 [4]. The input-output rules of the example are described in [7].…”

Applying CSP || B to information systems

“…The results in [14] state that B is capable of expressing the complex ordering of operations within their preconditions, and uses the invariant to represent static data integrity constraints of an information system. In this paper we argue that there is no need to express the complex ordering using predicates when the explicit ordering within a CSP description provides this more naturally and clearly.…”

Generating relational database transactions from eb 3 attribute definitions

“…For instance, safety properties are difficult to verify on recursive functions [15]. In [23], we have shown how to generate a B specification that corresponds to eb 3 attribute definitions and how to verify safety properties on that model.…”

“…eb 3 , which is a trace-based formal language that includes some state-oriented constructs, provides a different way of specifying IS, which is orthogonal in specification style with respect to state-based formal languages [15]. For instance, dynamic properties can be easily specified in eb 3 [11].…”