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Automata-Theoretic vs. Property-Oriented Approaches for the Detection of Feature Interactions in IN
(1999)
The feature interaction problem in Intelligent Networks obstructs more and morethe rapid introduction of new features. Detecting such feature interactions turns out to be a big problem. The size of the systems and the sheer computational com-plexity prevents the system developer from checking manually any feature against any other feature. We give an overview on current (verification) approaches and categorize them into property-oriented and automata-theoretic approaches. A comparisonturns out that each approach complements the other in a certain sense. We proposeto apply both approaches together in order to solve the feature interaction problem.
The feature interaction problem in telecommunications systems increasingly ob-structs the evolution of such systems. We develop formal detection criteria whichrender a necessary (but less than sufficient) condition for feature interactions. It can be checked mechanically and points out all potentially critical spots. Thesehave to be analysed manually. The resulting resolution decisions are incorporatedformally. Some prototype tool support is already available. A prerequisite forformal criteria is a formal definition of the problem. Since the notions of featureand feature interaction are often used in a rather fuzzy way, we attempt a formaldefinition first and discuss which aspects can be included in a formalization (andtherefore in a detection method). This paper describes ongoing work.
In nebenläufigen Systemen erleichtert das Konzept der Atomarität vonOperationen, konkurrierende Zugriffe in größere, leichter beherrschbareAbschnitte zu unterteilen. Wenn wir aber Spezifikationen in der forma-len Beschreibungstechnik Estelle betrachten, erweist es sich, daß es un-ter bestimmten Umständen schwierig ist, die Atomarität der sogenanntenTransitionen bei Implementationen exakt einzuhalten, obwohl diese Ato-marität eine konzeptuelle Grundlage der Semantik von Estelle ist. Es wirdaufgezeigt, wie trotzdem sowohl korrekte als auch effiziente nebenläufigeImplementationen erreicht werden können. Schließlich wird darauf hinge-wiesen, daß die das Problem auslösenden Aktionen oft vom Spezifiziererleicht von vorneherein vermieden werden können; und dies gilt auch überden Kontext von Estelle hinaus.
The feature interaction problem in telecommunications systems increasingly obstructsthe evolution of such systems. We develop formal detection criteria which render anecessary (but less than sufficient) condition for feature interactions. It can be checkedmechanically and points out all potentially critical spots. These have to be analyzedmanually. The resulting resolution decisions are incorporated formally. Some prototypetool support is already available. A prerequisite for formal criteria is a formal definitionof the problem. Since the notions of feature and feature interaction are often used in arather fuzzy way, we attempt a formal definition first and discuss which aspects can beincluded in a formalization (and therefore in a detection method). This paper describeson-going work.
A Case Study on Specifikation,Detection and Resolution of IN Feature Interactions with Estelle
(1994)
We present an approach for the treatment of Feature Interactions in Intelligent Networks. The approach is based on the formal description technique Estelle and consists of three steps. For the first step, a specification style supporting the integration of additional features into a basic service is introduced . As a result, feature integration is achieved by adding specification text, i.e . on a purely syntactical level. The second step is the detection of feature interactions resulting from the integration of additional features. A formal criterion is given that can be used for the automatic detection of a particular class of feature interactions. In the third step, previously detected feature interactions are resolved. An algorithm has been devised that allows the automatical incorporation of high-level design decisions into the formal specification. The presented approach is applied to the Basic Call Service and several supplementary interacting features.
AbstractOne main purpose for the use of formal description techniques (FDTs) is formal reasoningand verification. This requires a formal calculus and a suitable formal semantics of theFDT. In this paper, we discuss the basic verification requirements for Estelle, and howthey can be supported by existing calculi. This leads us to the redefinition of the stanADdard Estelle semantics using Lamport's temporal logic of actions and Dijkstra's predicatetransformers.
Correctness and runtime efficiency are essential properties of software ingeneral and of high-speed protocols in particular. Establishing correctnessrequires the use of FDTs during protocol design, and to prove the protocolcode correct with respect to its formal specification. Another approach toboost confidence in the correctness of the implementation is to generateprotocol code automatically from the specification. However, the runtimeefficiency of this code is often insufficient. This has turned out to be amajor obstacle to the use of FDTs in practice.One of the FDTs currently applied to communication protocols is Es-telle. We show how runtime efficiency can be significantly improved byseveral measures carried out during the design, implementation and run-time of a protocol. Recent results of improvements in the efficiency ofEstelle-based protocol implementations are extended and interpreted.
In diesem Aufsatz wird die Arbeitsweise eines Werkzeuges dargestellt, mit dessen Hilfedie Analyse von Feature-Interaktionen in Intelligenten (Telefon-)Netzwerken unterstütztwird. Dieses Werkzeug basiert auf einem von uns entwickelten formalen Lösungsansatz, deraus einem geeigneten Spezifikationsstil, aus einem formalen Kriterium zur Erkennung vonFeature-Interaktionen und aus einer Methode zur Auflösung der erkannten Feature- Interaktionen besteht. Das Werkzeug führt eine statische Analyse von Estelle-Spezifikationendurch und erkennt dabei potientielle Feature-Interaktionen sowie nichtausführbare Transitionen. Darüberhinaus kann es die erkannten nichtausführbaren Transitionen zur Optimierung aus der Spezifikation entfernen. Wir erläutern zunächst kurz den zugrundeliegendenAnsatz und beschreiben danach die Anwendung auf Estelle anhand der Funktionsweisedes Werkzeuges.