Ensuring interoperability between network elements in next generation networks

Next Generation Networks (NGNs), based on the Internet Protocol (IP), implement several services such as IP-based telephony and are beginning to replace the classic telephony systems. Due to the development and implementation of new powerful services these systems are becoming increasingly complex. Implementing these new services (typically software-based network elements) is often accompanied by unexpected and erratic behaviours which can manifest as interoperability problems. The reason for this caused by insufficient testing at the developing companies. The testing of such products is by nature a costly and time-consuming exercise and therefore cut down to what is considered the maximum acceptable level. Ensuring the interoperability between network elements is a known challenge. However, there exists no concept of which testing methods should be utilised to achieve an acceptable level of quality. The objective of this thesis was to improve the interoperability between network elements in NGNs by creating a testing scheme comprising of three diverse testing methods: conformance testing, interoperability testing and posthoc analysis. In the first project a novel conformance testing methodology for developing sets of conformance test cases for service specifications in NGNs was proposed. This methodology significantly improves the chance of interoperability and provides a considerable enhancement to the currently used interoperability tests. It was evaluated by successfully applying it to the Presence Service. The second report proposed a post-hoc methodology which enables the identification of the ultimate causes for interoperability problems in a NGN in daily operation. The new methods were implemented in the tool IMPACT (IP-Based Multi Protocol Posthoc Analyzer and Conformance Tester), which stores all exchanged messages between network elements in a database. Using SQL queries, the causes for errors can be found efficiently. Overall the presented testing scheme improves significantly the chance that network elements interoperate successfully by providing new methods. Beyond that, the quality of the software product is raised by mapping these methods to phases in a process model and providing well defined steps on which test method is the best suited at a certain stage

Conformance Testing with Labelled Transition Systems: Implementation Relations and Test Generation

This paper studies testing based on labelled transition systems, presenting two test generation algorithms with their corresponding implementation relations. The first algorithm assumes that implementations communicate with their environment via symmetric, synchronous interactions. It is based on the theory of testing equivalence and preorder, as is most of the testing theory for labelled transition systems, and it is found in the literature in some slightly different variations. The second algorithm is based on the assumption that implementations communicate with their environment via inputs and outputs. Such implementations are formalized by restricting the class of labelled transition systems to those systems that can always accept input actions. For these implementations a testing theory is developed, analogous to the theory of testing equivalence and preorder. It consists of implementation relations formalizing the notion of conformance of these implementations with respect to labelled transition system specifications, test cases and test suites, test execution, the notion of passing a test suite, and the test generation algorithm, which is proved to produce sound test suites for one of the implementation relations

Slicing approach to specification for testability in LOTOS

Ankara : Department of Computer Engineering and Information Science and Institute of Engineering and Science, Bilkent Univ., 1993.Thesis (Master's) -- Bilkent University, 1993.Includes bibliographical references leaves 119-123With the recent increase in the use of formal methods in specification of communication protocols, there is a need to base the conformance testing of protocol implementations on formal specifications. This brings in the problem of finding out special design issues to be used in the specification of such systems that facilitate test generation. This aspect is called Specification For Testability, and it is investigated in this study for the particular formal description technique LOTOS. Specification for testability is approached from the perspective of designing formal base protocol specifications, and then deriving functional specifications from base specifications in order to use in test generation. The method utilized for the derivation of functional specifications is Ccdled slicing. As inspired from previous work in software engineering, slices of protocol specifications are obtained systematically according to the hierarchically designed test suite structures, where each slice corresponds to a particular tunction of the protocol, and subsequent test generation is based on the obtained slices. The techni(|ues developed are demonstrated on the simple state-oriented specifications of INRES and ACSE protocols along with a real base specification of the OSI Transport Protocol written in the constraintoriented specification style. The results indicate that tests derived from functional specifications have some remarkable properties with respect to test case analysis and representation.Ateş, Ahmet FeyziM.S

Standardized event pair based test generation method using TSS&TP

In the software engineering test development takes significant resources. A general method for the creation of appropriate test suites could solve the problems of the often ad-hoc and time-consuming test generation process. The recent method uses formal specifications to support systematic derivation of complete test suites. From the formal specification using a special procedure a formalized document, the so-called Test Suite Structure (TSS) and Test Purposes (TP) can be created. With the help of this document developers can easily, automatically implement the test suites. The TSS&TP document also enables the persons who perform the tests to understand the test criteria and the steps, even if they do not actually know the protocol itself. We present a thorough picture of our test derivation method and show its efficiency on the Wireless Transaction Protocol (WTP) of the Wireless Application Protocol family (WAP). During our work in the validation phase we also found some operational flaws in the protocol specification

Design and implementation of a TTCN to C translator

The conformance testing of a protocol implementation, may be logically divided into, the specification of the abstract test suite (ATS) from a formal descnption of the protocol, and the subsequent derivation of the executable test suite (ETS) from the ATS specification. Our concern here is with the latter step, in particular, the automatic derivation of an ATS expressed in the Tree and Tabular Combined Notation (TTCN) to an executable C language equivalent. This process is currently a manual one, and as a consequence is error prone, time consuming, often repetitive and not necessarily consistent. To overcome these problems, there exists the real need for a computer aided, and if possible, fully automatic solution. This study descnbes the design and implementation of a fully working TTCN subset to C language translator, which takes a TTCN ATS and produces an equivalent ETS, with a minimal amount of manual intervention. The methodology used is logically divided into three stages direct TTCN to C language mappings, implementation issues, including the generation of additional code to drive the above mappings, and test system implementation issues. The system was tested using parts of an ETSI ISDN LAPD ATS and the results showed considerable time savings against a similar manual implementation. In conclusion, suggestions are provided to the further development of the TTCN to C translator system, and discussion is given to the apphcation of this tool to a complete conformance testing system