Engineering telecommunication services with SDL

If formal techniques are to be more widely accepted then they should evolve as current software engineering approaches evolve. Current techniques in the development of distributed systems use interface definition languages (IDLs) as a basis for the underlying communication and also as an abstraction tool. Object-oriented technologies [6] and the idea of engineering software through frameworks [5] are also widely accepted approaches in developing software. In this paper we show how the formal specification language SDL and associated tool support have been applied in the TOSCA1 project to engineer telecommunication services using these current techniques

The pros and cons of using SDL for creation of distributed services

In a competitive market for the creation of complex distributed services, time to market, development cost, maintenance and flexibility are key issues. Optimizing the development process is very much a matter of optimizing the technologies used during service creation. This paper reports on the experience gained in the Service Creation projects SCREEN and TOSCA on use of the language SDL for efficient service creation

Frameworks: the future of formal software development?

It could be argued that the primary issue to be dealt with in software engineering today is re-use of software. Current software development rarely, if ever, starts from nothing. Unfortunately, the same cannot be said for the development of specifications. To overcome this problem, various works have attempted to show how specifications can be built using architectural principles. We discuss one such approach in particular, the Architectural Semantics of Open Distributed Processing. We show the limitations of this work with regard to the architecting of specifications and propose a new approach, based on frameworks. To highlight the approach we use the work currently being done in the TOSCA project in its development of a service creation and validation environment for telecommunication services

Business-oriented development of telecommunication services

The development of software for distributed systems, e.g. telecommunication services, is a complex activity. Numerous issues have to be resolved when developing such systems, examples of which are language/system heterogeneity and remoteness of components. Interface definition languages (IDLs) are used as the basis for addressing some of these issues. IDLs allow for the specification of the syntactic aspects of the interfaces of the components in the system to be made. Whilst lending itself to issues of heterogeneity and location transparency, dealing with IDL as the basis for system development is not without its problems. Two of the main problems with IDL are its lack of behaviour and its lack of abstraction. Thus designers should not be constrained to work within the syntactic notations used to implement their systems, nor should they be unaided in how they might better design their systems. In this paper we show how these issues are being addressed in the TOSCA project in its development of a service creation and validation environment

Creating telecommunication services based on object-oriented frameworks and SDL

This paper describes the tools and techniques being applied in the TINA Open Service Creation Architecture (TOSCA) project to develop object-oriented models of distributed telecommunication services in SDL. The paper also describes the way in which Tree and Tabular Combined Notation (TTCN) test cases are derived from these models and subsequently executed against the CORBA-based implementations of these services through a TTCN/CORBA gateway

Finite state machine based SDL

No abstract available

What makes industries believe in formal methods

The introduction of formal methods in the design and development departments of an industrial company has far reaching and long lasting consequences. In fact it changes the whole environment of methods, tools and skills that determine the design culture of that company. A decision to replace current design practice by formal methods, therefore, appears a vital one and is not lightly taken. The past has shown that efforts to introduce formal methods in industry has faced a lot of controversy and opposition at various hierarchical levels in companies, resulting in a marginal spread of such methods. This paper revisits the requirements for formal description techniques and identifies some critical success and inhibiting factors associated with the introduction of formal methods in the industrial practice. One of the inhibiting factors is the often encountered lack of appropriateness of the formal model to express and manipulate the design concerns that determine the world of the engineer. This factor motivated our research in the area of architectural and implementation design concepts. The last two sections of this paper report on some results of this research

On the testability of SDL specifications

The problem of testing from an SDL specification is often complicated by the presence of infeasible paths. This paper introduces an approach for transforming a class of SDL specification in order to eliminate or reduce the infeasible path problem. This approach is divided into two phases in order to aid generality. First the SDL specification is rewritten to create a normal form extended finite state machine (NF-EFSM). This NF-EFSM is then expanded in order to produce a state machine in which the test criterion may be satisfied using paths that are known to be feasible. The expansion process is guaranteed to terminate. Where the expansion process may lead to an excessively large state machine, this process may be terminated early and feasible paths added. The approach is illustrated through being applied to the Initiator process of the Inres protocol

Engineering of interworking TINA-based telecommunication services

This paper describes a Service Creation approach being developed in the EU funded ACTS TOSCA (TINA Open Service Creation Architecture) project to rapidly develop validated TINA based multimedia telecommunications services. The approach is based around object-oriented software frameworks in SDL which are specialized towards services by means of graphical paradigm tools. Further, in TOSCA, the need for service interworking across service provider domains via federation has been recognized in order to allow users to join service sessions offered by providers they are not customers of. However, service interworking may cause undesired behavior - the so called service interaction phenomenon. This paper focuses on this issue and the underlying technology of the service creation approach with emphasis on how service federation has been implemented