Simulated time for testing railway interlockings with TTCN-3

In this report, we first give an overview of software systems based on Vital Processor Interlocking (VPI). Interlockings guarantee safety of railway control systems, so testing these software systems is a key issue. We show why testing such systems with real time and scaled time is inefficient. We also provide a time semantics for simulated time that is more suitable for testing VPI's software. We provide a solution that allows simulated time for TTCN-3 test systems. TTCN-3 is a standard language for specifying and executing test suites. In the context of the TT-MEDAL project, TTCN-3 is applied to various domains, in particular to testing railway and automotive systems. TTCN-3 supports real-time and scaled-time testing but not simulated-time testing. The solution is based on a distributed termination detection algorithm that we extend to provide the main ingredients of simulated time: idleness detection and correct time progress. We implemented our solution as a TTCN-3 module and several Java classes that can be reused for testing other systems that have characteristics similar to those of VPI

Towards more accurate real time testing

The languages Message Sequence Charts (MSC) [1], System Design Language1 (SDL) [2] and Testing and Test Control Notation Testing2 (TTCN-3) [3] have been developed for the design, modelling and testing of complex software systems. These languages have been developed to complement one another in the software development process. Each of these languages has features for describing, analysing or testing the real time properties of systems. Robust toolsets exist which provide integrated environments for the design, analysis and testing of systems, and it is claimed, for the complete development of real time systems. It was shown in [4] however, that there are fundamental problems with the SDL language and its associated tools for modelling and reasoning about real time systems. In this paper we present the limitations of TTCN-3 and propose recommendations which help minimise the timing inaccuracies that would otherwise occur in using the language directly

Testing real-time systems using TTCN-3

In system engineering, testing plays an important role to validate systems and system components. As the market time becomes ever shorter and the requirements on system features, reliability, availability, integrity and performance further increase, assured quality of system and its components is very important. Moreover, in real-time systems extreme reliability and safety are the most fundamental requirements. Thus, in order to fulfill the requirements of such systems as well as those of the market, a systematic proficient approach to testing is an essential need. The Testing and Test Control Notation TTCN-3 has been developed by ETSI to address testing needs and to enable systematic specification-based testing for software systems. This thesis will discuss in particular the use of TTCN-3 for testing real-time software systems. It takes textual test cases that have previously been generated for a particular real-time application. Each of them has input actions, time delays, and output actions. Then, the thesis explains the procedure of transforming the generated test cases into a test suite coded in TTCN-3. After that, it shows the process of creating and implementing the required TTCN-3 interfaces to complete the test system and follows it by running the test system and analysing the results. To define the black-box testing procedure of these timed test cases, stimuli are applied on the system under test. Then, the reactions are observed and compared with the expected ones with respect to the time delays. According to this comparison, a test verdict assignment is set to determine the test behaviour of each test case. If the expected and the observed responses are matched while respecting the value of the related timers, a test verdict is set to "pass" indicating a successful test case. Otherwise, the verdict is set to "fail" signifying an unsuccessful test cas

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

Architecting specifications for test case generation

The Specification and Description Language (SDL) together with its associated tool sets can be used for the generation of Tree and Tabular Combined Notation (TTCN) test cases. Surprisingly, little documentation exists on the optimal way to specify systems so that they can best be used for the generation of tests. This paper, elaborates on the different tool supported approaches that can be taken for test case generation and highlights their advantages and disadvantages. A rule based SDL specification style is then presented that facilitates the automatic generation of tests

ERIGrid Holistic Test Description for Validating Cyber-Physical Energy Systems

Smart energy solutions aim to modify and optimise the operation of existing energy infrastructure. Such cyber-physical technology must be mature before deployment to the actual infrastructure, and competitive solutions will have to be compliant to standards still under development. Achieving this technology readiness and harmonisation requires reproducible experiments and appropriately realistic testing environments. Such testbeds for multi-domain cyber-physical experiments are complex in and of themselves. This work addresses a method for the scoping and design of experiments where both testbed and solution each require detailed expertise. This empirical work first revisited present test description approaches, developed a newdescription method for cyber-physical energy systems testing, and matured it by means of user involvement. The new Holistic Test Description (HTD) method facilitates the conception, deconstruction and reproduction of complex experimental designs in the domains of cyber-physical energy systems. This work develops the background and motivation, offers a guideline and examples to the proposed approach, and summarises experience from three years of its application.This work received funding in the European Community’s Horizon 2020 Program (H2020/2014–2020) under project “ERIGrid” (Grant Agreement No. 654113)

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

The formal, tool supported development of real time systems

The language SDL has long been applied in the development of various kinds of systems. Real-time systems are one application area where SDL has been applied extensively. Whilst SDL allows for certain modelling aspects of real-time systems to be represented, the language and its associated tool support have certain drawbacks for modelling and reasoning about such systems. In this paper we highlight the limitations of SDL and its associated tool support in this domain and present language extensions and next generation real-time system tool support to help overcome them. The applicability of the extensions and tools is demonstrated through a case study based upon a multimedia binding object used to support a configuration of time dependent information producers and consumers realising the so called lip-synchronisation algorithm

Report on the Standardization Project ``Formal Methods in Conformance Testing''

This paper presents the latest developments in the “Formal Methods in Conformance Testing” (FMCT) project of ISO and ITU–T. The project has been initiated to study the role of formal description techniques in the conformance testing process. The goal is to develop a standard that defines the meaning of conformance in the context of formal description techniques. We give an account of the current status of FMCT in the standardization process as well as an overview of the technical status of the proposed standard. Moreover, we indicate some of its strong and weak points, and we give some directions for future work on FMCT