This paper presents the overal structure, the design criteria, and the main features of the tool box Uppaal. It gives a detailed user guide which describes how to use the various tools of Uppaal version 2.02 to construct abstract models of a real-time system, to simulate its dynamical behavior, to specify and verify its safety and bounded liveness properties in terms of its model. In addition, the paper also provides a short review on case-studies where Uppaal is applied, as well as references to its theoretical foundation.

UPPAAL in a Nutshell

https://www.cis.upenn.edu/~alur/TCS95.pdf

The algorithmic analysis of hybrid systems

Part 1 Basic: introduction protocol structure error control flow control. Part 2 Specification and modeling: validation models correctness requirements protocol design finite state machines. Part 3 Conformance testing synthesis and validation: conformance testing protocol synthesis protocol validation. Part 4 Design tools: a protocol simulator a protocol validator using the validator.

/pdf/design-and-validation-of-computer-protocols-39ngbrhx80.pdf

Design and validation of computer protocols

With advanced computer technology, systems are getting larger to fulfill more complicated tasks: however, they are also becoming less reliable. Consequently, testing is an indispensable part of system design and implementation; yet it has proved to be a formidable task for complex systems. This motivates the study of testing finite stare machines to ensure the correct functioning of systems and to discover aspects of their behavior. A finite state machine contains a finite number of states and produces outputs on state transitions after receiving inputs. Finite state machines are widely used to model systems in diverse areas, including sequential circuits, certain types of programs, and, more recently, communication protocols. In a testing problem we have a machine about which we lack some information; we would like to deduce this information by providing a sequence of inputs to the machine and observing the outputs produced. Because of its practical importance and theoretical interest, the problem of testing finite state machines has been studied in different areas and at various times. The earliest published literature on this topic dates back to the 1950's. Activities in the 1960's mid early 1970's were motivated mainly by automata theory and sequential circuit testing. The area seemed to have mostly died down until a few years ago when the testing problem was resurrected and is now being studied anew due to its applications to conformance testing of communication protocols. While some old problems which had been open for decades were resolved recently, new concepts and more intriguing problems from new applications emerge. We review the fundamental problems in testing finite state machines and techniques for solving these problems, tracing progress in the area from its inception to the present and the stare of the art. In addition, we discuss extensions of finite state machines and some other topics related to testing.

Principles and methods of testing finite state machines-a survey

We introduce the framework of hybrid automata as a model and specification language for hybrid systems. Hybrid automata can be viewed as a generalization of timed automata, in which the behavior of variables is governed in each state by a set of differential equations. We show that many of the examples considered in the workshop can be defined by hybrid automata. While the reachability problem is undecidable even for very restricted classes of hybrid automata, we present two semidecision procedures for verifying safety properties of piecewiselinear hybrid automata, in which all variables change at constant rates. The two procedures are based, respectively, on minimizing and computing fixpoints on generally infinite state spaces. We show that if the procedures terminate, then they give correct answers. We then demonstrate that for many of the typical workshop examples, the procedures do terminate and thus provide an automatic way for verifying their properties.

/pdf/hybrid-automata-an-algorithmic-approach-to-the-specification-90c14uxt2h.pdf

Hybrid Automata: An Algorithmic Approach to the Specification and Verification of Hybrid Systems

We are given a transition system implicitly through a compact representation and wish to perform simultaneously reachability analysis and minimization without constructing first the whole system graph. We present an algorithm for this problem that applies to general systems, provided we have appropriate primitive operations for manipulating blocks of states and we can determine termination; the number of operations needed to construct the minimal reachable graph is quadratic in the size of this graph. We specialize the method to obtain efficient algorithms for extended finite state machines that apply separable affine transformations on the variables.

Online minimization of transition systems (extended abstract)

An important aspect of network management is fault management-determining, locating, isolating and correcting faults in the network. The paper deals with the algorithms for detecting faults, i.e., behavior of the network different from specifications. It is important for communication networks to detect faults "in-process" i.e., while the network is in its normal operation. Thus, we detect faults by examining the input-output behavior without forcing the system to specialized inputs explicitly for testing. Such testing is commonly called passive testing. We model the network as a finite state machine and develop procedures for passive testing including the required data structure, efficient implementations and the complexity of our procedures. We start with fully observable and deterministic machines and then study more realistic models: partially observable and nondeterministic machines. We also discuss extensions to communicating finite state machines and machines extended with parameters and variables. We apply our techniques to management of a signaling network operating under the Signaling System 7 (SS7) and report experimental results, which show the feasibility of applying passive testing to practical systems.

Passive testing and applications to network management

Testing finite state machines: fault detection

We present a new approach for conformance testing of protocols specified as a collection of communicating finite state machines (FSMs). Our approach uses a guided random walk procedure. This procedure attempts to cover all transitions in the component FSMs. We also introduce the concept of observers that check some aspect of protocol behavior. We present the result of applying our method to two example protocols: full-duplex alternating bit protocol and the ATM-adaptation-layer-convergence protocol. Applying our procedure to the ATM adaptation layer, 99% of component FSMs edges can be covered in a test with 11692 input steps. Previous approaches cannot do conformance test generation for standard protocols (such as asynchronous transfer mode (ATM) adaptation layer) specified as a collection of communicating FSMs.

David Lee

Papers

Principles and methods of testing finite state machines-a survey

Online minimization of transition systems (extended abstract)

Passive testing and applications to network management

Testing finite state machines: fault detection

Conformance testing of protocols specified as communicating finite state machines-a guided random walk based approach