Felipe Lalanne

A formal data-centric approach for passive testing of communication protocols

There is currently a high level of consciousness of the importance and impact of formally testing communicating networks. By applying formal description techniques and formal testing approaches, we are able to validate the conformance of implementations to the requirements of communication protocols. In this context, passive testing techniques are used whenever the system under test cannot be interrupted or access to its interfaces is unavailable. Under such conditions, communication traces are extracted from points of observation and compared to the expected behavior formally specified as properties. Since most works on the subject come from a formal model context, they are optimized for testing the control part of the communication with a secondary focus on the data parts. In the current work, we provide a data-centric approach for black-box testing of network protocols. A formalism is provided to express complex properties in a bottom-up fashion starting from expected data relations in messages. A novel algorithm is provided for evaluation of properties in protocol traces. Experimental results on Session Initiation Protocol (SIP) traces for IP Multimedia Subsystem (IMS) services are provided.

QoE Estimation for Web Service Selection Using a Fuzzy-Rough Hybrid Expert System

With the proliferation of web services on the Inter-net, it has become important for service providers to select the best services for their clients in accordance to their functional and non-functional requirements. Generally, QoS parameters are used to select the most performing web services, however, these parameters do not necessarily reflect the users satisfaction. Therefore, it is necessary to estimate the quality of web services on the basis of user satisfaction, i.e., Quality of Experience(QoE). In this paper, we propose a novel method based on a fuzzy-rough hybrid expert system for estimating QoE of web services for web service selection. It also presents how different QoS parameters impact the QoE of web services. For this, we conducted subjective tests in controlled environment with real users to correlate QoS parameters to subjective QoE. Based on this subjective test, we derive membership functions and inference rules for the fuzzy system. Membership functions are derived using a probabilistic approach and inference rules are generated using Rough Set Theory (RST). We evaluated our system in a simulated environment in MATLAB. The simulation results show that the estimated web quality from our system has a high correlation with the subjective QoE obtained from the participants in controlled tests.

An Automated Passive Testing Approach for the IMS PoC Service

Although the adoption of the IP Multimedia Subsystem (IMS) keeps growing, IMS applications are often integrated to the system without being formally tested. In this work, we are interested in the IMS Push over Cellular (PoC) service, an OMA standard. We propose a conformance passive testing approach to check that its implementation respects the main standard requirements. This approach is based on a set of formal invariants representing the most relevant expected properties to be tested. Two testing phases are applied: the verification of the invariants against the service specification and their testing on the PoC collected execution traces.

Adkintun: SLA Monitoring of ISP Broadband Offerings

Broadband Internet access has become a regular commodity on households around the world. For this reason, initiatives for characterization and monitoring of service offerings by Internet Service Providers (ISPs), by governments, researchers and independent entities have grown in popularity in the last few years. In this context, we present Adkintun, the Chilean initiative commanded by the Transports and Telecommunications Ministry (MTT) of Chile to NIC Chile Research Labs, in order to characterize the growing broadband Internet offer in that country providing an independent tool for consumers to monitor the effective quality of their provided service, and perform informed choices among chilean internet providers. In this article, we present the design, architecture and main results of Adkintun after a year of monitoring, measuring and characterizing chilean internet.

DataMonitor - A formal approach for passively testing a MANET routing protocol

By applying formal description techniques and formal testing approaches, it is possible to validate the conformance of implementations to the requirements of communication protocols. However, and particularly in wireless communications systems, most of the testing work is devoted to the evaluation of their performance in a simulated environment without formal descriptions. The current work expands on our formal approach for black-box testing of network protocols implemented in the tool DataMonitor, and it demonstrates its applications for MANET routing protocols through passive testing on OLSR traces. With such application, we show how our formal approach can help express complex properties from data relations in messages and evaluated them on real traces. The results from our experiments with an OLSR implementation are provided.

Protocol Data Parts Inclusion in a Formal Passive Testing Approach

Commonly, two main classes of formal testing techniques are applied to check the conformance of protocols and software: active and passive testing (monitoring) techniques. Because of many industrial constraints such as the necessity to achieve implementation black box testing, passive testing techniques become highly relevant in several cases. Besides, most of the passive testing techniques only consider control portions of exchanged packets and ignores data parts. However, since systems become more complex, testing for data constraints and relations between packets is now essential. In this paper we propose a novel approach for defining data oriented invariants and show how they can be tested in a trace set by using logic programming. Experimental results on SIP protocol traces are provided.

From the IMS PoC service monitoring to its formal conformance testing

Because of the increased industrial and research communities interest in the IP Multimedia Subsystem (IMS), the needs of formal testing for IMS applications are becoming critical. In this work we take as a case study the IMS Push over Cellular (PoC) service, an OMA standard, and propose a formal testing approach to check that its implementation respects the standard requirements. The approach considers a formal model of the service as well a set of formal invariants representing the most relevant properties expected from the implementation. The invariants are verified on the PoC formal specification and then automatically checked on the execution traces of the implementation. Experimental results are then processed to provide testing verdicts on the implementation under test. Besides, we discuss the results analysis that show false positives essentially raised by inter-working SIP services.

A Formal Monitoring Technique for SIP Conformance Testing

Formal approaches provide many keys to efficiently test the conformance of communicating protocols. Active and passive testing techniques are two main sets of these approaches. Compare to active testing, passive testing techniques are used whenever the system cannot be interrupted, or its interfaces are unavailable to access. Under such conditions, communication traces are extracted from points of observation and compared with the expected conformance requirements formally specified as properties. This paper presents a novel monitoring approach, aiming at formally specifying protocol properties in order to check them on real execution traces. A prototype is developed and experienced based on the algorithms defined in a previous paper. Experiments are presented through a set of IMS/SIP properties and numerous execution traces in order to evaluate and assess our technique. The relevant verdicts and discussions are provided at the end.