The elicitation, modeling and analysis of requirements have consistently been one of the main challenges during the development of complex systems. Telecommunication systems belong to this category of systems due to the worldwide distribution and the heterogeneity of today’s telecommunication networks. Scenarios and use cases have become popular for capturing and analyzing requirements. However, little research has been done that compares different approaches and assesses their suitability for the telecommunications domain. This paper defines evaluation criteria and then reviews fifteen scenario notations. In addition, twenty-six approaches for the construction of design models from scenarios are briefly compared.

The elicitation, modeling and analysis of requirements have consistently been one of the main challenges during the development of complex systems. Telecommunication systems belong to this category of systems due to the worldwide distribution and the heterogeneity of today’s telecommunication networks. Many proposals have been made for approaches that allow the developer to describe system behavior. Scenarios and use cases represent one such approach that has become popular for the capturing and analysis of requirements. However, little research has been done that compares different approaches and assesses their suitability for the telecommunications domain. This paper defines evaluation criteria for scenario notations and then uses these criteria to review twelve scenario notations. In addition, nineteen approaches for the construction of more detailed and integrated design models from scenarios are briefly compared. Such models enable further analysis and pave the way towards automated generation of implementations. Hopes and challenges related to scenario-based development of telecommunication systems are finally discussed.

In general, the services of a distributed system are provided by some cooperative protocol entities. The protocol entities must exchange some data values and synchronization messages in order to ensure the temporal ordering of the events which are described in a service specification of the distributed system. It is desirable that a correct protocol entity specification for each node can be derived automatically from a given service specification. In this paper

In this paper, we propose a method to synthesize protocol specifications automatically from service specifications written in a time-extended LOTOS called LOTOS/T+. In LOTOS/T+, structured descriptions, such as parallelism and interruption are allowed to describe service specifications, and time-constraints among non-adjacent actions can be described using Presburger formulas. Here we assume that there is a reliable communication channel between any two nodes and the maximum communication delay for each channel is bounded by a constant. Moreover we assume service specifications have no deadlocks. Under our simulation policy, a specification S

One of the biggest challenges in obtaining truly autonomic, selfmanaged networks is to automate the process of software evolution, and in particular, the evolution of protocol implementations and configurations. Such networks ultimately require self-modifying, evolving protocol software. Otherwise humans must intervene in every situation that has not been anticipated at design time. For this to become feasible autonomic systems must ensure non-disruptive, resilient on-line software evolution. We are starting to explore approaches to network evolution that operate directly at the code level. We investigate related code steering techniques in two directions: One is the fully automatic selection of protocol service elements where, depending on device characteristics and current operation environment, each communication entity has to select among a potentially wide variety of protocol implementations providing similar services. The other direction relates to the automatic synthesis of new protocol elements which are the result of optimizing existing implementations for a specific context. In both cases we look at genetic programming as a tool to generate new code and software configurations automatically. We propose a framework for such a resilient protocol evolution and report on first exploratory results on the adaptation and re-adaptation to environmental conditions, and the elimination of superfluous code.

Abstract not found

We propose a specification model and present a method to algorithmically derive a protocol specification from a service specification based on the model. Unlike the previous models based on finite state machines, the proposed model can explicitly express concurrency, synchronization, and timing requirements such as delays and timeouts. We assume that there exists a reliable communication channel between any two protocol entities and the maximum delay for each channel is bounded by a positive constant. Because of the variable nature of the communication delays along with the time constraints associated with events, no protocol specification can fully simulate the service specification. The proposed method derives a protocol specification that is optimal in the sense that it provides the largest possible subset of the service specification under the communication delay constraints. We also give a method to derive a sub specification from a service specification and a maximum communicatio...

The use of the formal design method FOCUS is illustrated by an example development of the so-called Stenning-protocol. The development process starts from global, non-constructive service specifications and ends in executable programs of the protocol entities. The four abstraction levels of FOCUS -- trace specification, functional specification, abstract program, and concrete program -- are covered. Special emphasis is put on the design steps within and between the first two abstraction levels, which are also proven correct.

The submodule construction problem (SCP) as stated and formulated by Merlin and Bochmann [P. Merlin, G.V. Bochmann, On the construction of submodule specification and communication protocols, ACM Trans. Prog. Lang. Sys., 5(1) (1983) 1--25] is considered: given the specification of a system (module) and that of its n 2 1 submodules, determine the specification of the nth submodule that together with the given n 2 1 submodules will satisfy the given system specification. We recast SCP in a formal setting and proceed to present and prove the correctness of an algorithm for the solution of SCP where submodules are prefix-closed finite state machines. q 1999 Elsevier Science B.V. All rights reserved. Keywords: Concurrent systems; Stepwise refinement; Submodule construction problem 1.

Abstract — One of the biggest challenges in obtaining truly self-managed networks is to automate the process of software evolution, and in particular, the evolution of protocol implementations and configurations. In this paper we explore an approach to network evolution that works inside the network software to manage and which operates directly at the code level. We investigate related code steering techniques in two directions: One is the fully automatic selection of protocol service elements where, depending on device characteristics and current operation environment, each communication entity has to select among a potentially wide variety of protocol implementations providing similar services. The other direction relates to the automatic synthesis of new protocol elements which are the result of optimizing existing implementations for a specific context. We use genetic programming as a tool to generate new configurations and new code automatically. In this paper we present a framework for injecting such code into a running environment in a nondisruptive way and report on first exploratory results on resilient protocol evolution. I.