The combination of Federated Learning (FL), Multimodal Large Language Models ( MLLMs ), and edge-cloud computing enables distributed and real-time data processing while preserving privacy across edge devices and cloud infrastructure. However, the deployment of MLLMs in FL environments with resource-constrained edge devices presents significant challenges, including resource management, communication overhead, and non-IID data. To address these challenges, we propose a novel hybrid framework wherein MLLMs are deployed on edge devices equipped with sufficient resources and battery life, while the majority of training occurs in the cloud. To identify suitable edge devices for deployment, we employ Particle Swarm Optimization ( PSO ), and Ant Colony Optimization ( ACO ) is utilized to optimize the transmission of model updates between edge and cloud nodes. This proposed swarm intelligence-based framework aims to enhance the efficiency of MLLM training by conducting extensive training in the cloud and fine-tuning at the edge, thereby reducing energy consumption and communication costs. The framework is particularly applicable in Unmanned Vehicle System (UVS)-based edge-cloud computing environments, where efficient resource management and real-time decision-making are critical for autonomous operations. The autonomous nature of UVS requires efficient resource management and a reliable communication system. The proposed swarm intelligence-based framework aims to satisfy these requirements through optimized edge device selection, while minimizing communication overhead. Our experimental results show that the proposed method significantly improves system performance, achieving an accuracy of 92%, reducing communication cost by 30%, and enhancing client participation compared to traditional FL methods. These results make the proposed approach highly suitable for large-scale edge-cloud computing systems.

Extending workflow orchestration to embrace monitoring and adaptation within cloud environment is perceived to be a challenging activity. It has to consider different resources, require heavy processing to adapt to the dynamic nature of cloud environment. In this paper, we propose a multi-model framework for workflow resource monitoring, prediction, and adaptation. The framework supports continuous monitoring of several workflow runtime cloud entities and detect diverse types of violations (e.g. resource saturation). Moreover, collected logs resulted from monitoring are used as a training dataset for predicting resource shortage. Furthermore, two adaptation strategies are proposed to cope with environment resources changes and avoid violations: 1) monitoring-based adaptation and 2) prediction-based adaptation. Both adaptation schemes perform the necessary actions to adapt resources according to workflow required quality levels. To evaluate our monitoring and adaptation approaches we used a real cloud environment where we perform a couple of experimental scenarios. Experiments results showed that our framework and proposed monitoring, prediction and adaptation schemes are efficient in detecting violations, accurately predicting cloud resource shortages and accordingly issuing the proper adapting decisions.

Social approaches have been put forward to define semantics for intelligent agent communication messages and to tackle the shortcomings of mental approaches. Formal semantics of those social approaches can be model checked as they are focused on public behaviors instead of private mental states. Social conditional commitments are essential concepts in social approaches that can effectively model agent communications. However, conditional commitments exclusively are not able to model agent communication actions, the cornerstone of the fundamental agent communication theory, namely speech act theory. These actions provide mechanisms for dynamic interactions and enable designers to track the evolution of active conditional commitments. From the perspective of model checking, we need to define a formal and computationally grounded semantics for relevant social actions that can directly be applied to active conditional commitments. This manuscript describes a new symbolic model checker, SMC4AC, developed and implemented to automate the verification of interaction among intelligent agents. SMC4AC is the result of developing a new symbolic model checking algorithm devoted to CTLC α , a combination of CTL and new temporal modalities to represent and reason about conditional commitments and common commitment actions. The core of this paper consists of a new logical language, a detailed description of the symbolic algorithms needed for commitments and their action modalities, complexity analysis, implementation and application. The implementation of our algorithm and its graphical user interface is built on top of the MCMAS symbolic model checker tailored for checking intelligent multi-agent systems. We select business processes and multi-agent interaction protocols as application domains to test and validate the effectiveness and scalability of SMC4AC. We report extensive experimental results, which confirm the theoretical findings and make SMC4AC practical.

The ability to compose web services from available services is one of the most crucial problems in the service-oriented computing paradigm. Conventional software engineering approaches and even standard languages compose web services as workflow models that control the business logic required to coordinate data over participating services. Such models would not apply to the design of multiagent-based web services, which offer high-level abstractions that support autonomy, business-level compliance, and flexible dynamic changes. In this paper, we model interactions among multiagent-based services by commitment modalities in the figure of contractual obligations and devote multiagent commitment protocols to regulate such interactions and engineer services composition. We develop and fully implement a symbolic model checking algorithm by enriching the MCMAS model checker with certain symbolic algorithms to verify the correctness of protocols, given properties expressed in a temporal commitment logic, suitably extended with actions. The time complexity and space complexity of the developed algorithm are P-complete for explicit models and for PSPACE-complete concurrent programs. Finally, we report the experimental results of two case studies, adopted to check the algorithm's efficiency.

While modeling interactions using social commitments provides a fundamental basis for capturing flexible and declarative interactions and helps in addressing the challenge of ensuring compliance with specifications, the designers of the system cannot guarantee that an agent complies with its commitments as it is supposed to, or at least an agent doesn't want to violate its commitments. They may still wish to develop efficient and scalable algorithms by which model checking conditional commitments, a natural and universal frame of social commitments, is feasible at design time. However, distinguishing between different but related types of conditional commitments, and developing dedicated algorithms to tackle the problem of model checking conditional commitments, is still an active research topic. In this article, we develop the temporal logic CTL cc that extends Computation Tree Logic (CTL) with new modalities which allow representing and reasoning about two types of communicating conditional commitments and their fulfillments using the formalism of interpreted systems. We introduce a set of rules to reason about conditional commitments and their fulfillments. The verification technique is based on developing a new symbolic model checking algorithm to address this verification problem. We analyze the computational complexity and present the full implementation of the developed algorithm on top of the MCMAS model checker. We also evaluate the algorithm's effectiveness and scalability by verifying the compliance of the NetBill protocol, taken from the business domain, and the process of breast cancer diagnosis and treatment, taken from the health-care domain, with specifications expressed in CTL cc . We finally compare the experimental results with existing proposals.

Network virtualization is considered as a promising way to overcome the limitations and fight the gradual ossification of the current Internet infrastructure. The network virtualization concept consists in the dynamic creation of several co-existing logical network instances (or virtual networks) over a shared physical network infrastructure. One of the challenges associated with this concept is the dynamic discovery and selection of virtual resources that can be composed to form virtual networks. To achieve that task, there is a need for a formal and expressive information model facilitating information representation and sharing between the various roles/entities involved. We have previously proposed a service-oriented hierarchical business model for virtual networking environments, as well as an architecture enabling its realization. In this paper, we build on this business model and architecture by proposing a multiservice, multi-role hierarchical information model, for virtual networking environments. Furthermore, we demonstrate the usage of this information model using a secure content distribution scenario that is realized using REST interfaces. Unlike other proposals, our integrated information model enables the fine-grained description of virtual networks and virtual networking resources, in addition to the modeling of network services and roles, and their relationships and hierarchy.

Network virtualization is a promising and technically challenging concept, which enables the dynamic creation of several co-existing logical network instances (or virtual networks) over a shared physical network infrastructure. There are several motivations behind this concept, including: cost-effective sharing of resources; customizable networking solutions; and the convergence of existing network infrastructures. We have previously proposed a new business model for virtual networking environments. In this paper, we use this model as well as concrete use cases as basis for the definition of the Open Virtual Playground - an open virtual multi-services networking architecture in which different levels of services (i.e. essential services, service enablers, service building blocks, and end-user services) offered by various players, can be dynamically discovered, used, and composed. Furthermore, a QoS-enabled VoIP service scenario is used to demonstrate the system operation and preliminary performance measurements are collected.

Mashup is a web technology that allows different service providers to flexibly integrate their expertise and to deliver highly customizable services to their customers. Data mashup is a special type of mashup application that aims at integrating data from multiple data providers depending on the user's request. However, integrating data from multiple sources brings about three challenges: 1) Simply joining multiple private data sets together would reveal the sensitive information to the other data providers. 2) The integrated (mashup) data could potentially sharpen the identification of individuals and, therefore, reveal their person-specific sensitive information that was not available before the mashup. 3) The mashup data from multiple sources often contain many data attributes. When enforcing a traditional privacy model, such as K-anonymity, the high-dimensional data would suffer from the problem known as the curse of high dimensionality, resulting in useless data for further data analysis. In this paper, we study and resolve a privacy problem in a real-life mashup application for the online advertising industry in social networks, and propose a service-oriented architecture along with a privacy-preserving data mashup algorithm to address the aforementioned challenges. Experiments on real-life data suggest that our proposed architecture and algorithm is effective for simultaneously preserving both privacy and information utility on the mashup data. To the best of our knowledge, this is the first work that integrates high-dimensional data for mashup service.

Service computing has become a very promising area of research and development for business-to-business integration, enterprise service migration and communication on the Internet. It provides the potential of communicating businesses online, and expands to become a large scale organization. Service market is growing continuously and need for service innovation is associated with demands for service research and education. Initiatives for service computing curriculum started in addressing/incorporating service courses within graduate programs for instance computer science, software engineering, and web engineering. Ideas for developing a program for service computing is in its initial state and some initiatives are ongoing. In this paper, we describe a case study of Master of Science in Service Computing proposal. We propose the curriculum structure that consists of key core courses, business process modeling and implementation courses, in addition to specialized key courses on service computing. We finally highlight the implementation of this curriculum and the possible issues that might be faced.

The IP Multimedia Subsystem (IMS) is a key component of 3G networks aimed at enabling the seamless provisioning of IP multimedia services to end users. Multiparty sessions (or conferences), which enable the conversational exchange of multimedia content between several parties, represent one of the specialized services supported by the IMS. Conferencing is the basis of a wide range of applications such as: debating; multiplayer gaming; and distance learning. In order to offer users a predictable experience and a controlled quality when using such applications, suitable QoS mechanisms must be supported in the IMS. We have previously proposed a two-party call differentiation scheme along with an architectural framework enabling its realization in the IMS. In this work, we apply our call differentiation scheme to the conferencing case, by studying the effects of call differentiation on the operation of the standard IMS conferencing architecture. This is achieved via a case study including the definition of a differentiated IMS conferencing architecture, the elaboration of various differentiated multiparty sessions scenarios, and the implementation of a proof-of-concept prototype.

The IP Multimedia Subsystem (IMS) is becoming the de-facto standard for IP-based multimedia services, while Wireless Sensor Networks (WSNs) are gaining a lot of popularity due to their ability of capturing a rich set of contextual information and their high application potential. Making the rich set of contextual information, captured by WSNs, available to the IMS can greatly enhance its service provisioning capabilities and open the door to a wide range of novel multimedia services. We have previously proposed a solution for WSNs/IMS integration. One of the key components of this solution is a WSN/IMS gateway acting as intermediary between the two networks. This paper focuses on the design and implementation of this gateway. The gateway architecture proposed encompasses the information management and support functions needed to enable IMS interaction with different types of WSNs. A prototype of this architecture is built and tested using Ericsson's IMS simulated environment. Furthermore, two applications (a pervasive game and a personalized call control application) are used to demonstrate the system operation.

Telehealth applications can deliver medical services to patients at remote locations using telecommunications technologies, such as the Internet. At the same time, such applications also pose unique security challenges. First, the trust issue becomes more severe due to the lack of visual proofs in telehealth applications. The public key infrastructure (PKI) is insufficient for providing the same kind of trust a patient may attain during a face-to-face service. Second, telehealth services, such as tele-monitoring or tele-consultant, naturally demand a systematic organization of users, roles, resources, and flows of information. Existing access control mechanisms in an e-health system are usually incapable of dealing with such workflow-based services. This paper provides cost-efficient solutions to those issues in the context of a Web-based e-health portal system. First, we propose a PKI-like infrastructure for establishing trust between users using biometrics-based authentication and hierarchies of trust. Second, we develop an access control method for workflow-based telehealth services using a rule-based module already available in the portal system.

Multihop Cellular Networks (MCNs) are an example of the integration of 3G and mobile ad hoc networks (MANETs). In this integration, single-hop cellular networks and MANETs coexist and cooperate. 4G networks are seen as the coexistence and cooperation of legacy (e.g 3G) and new (e.g. MANET) networks. This makes integrated 3G/MANET and particularly multihop cellular networks part of the 4G vision. MCNs have now emerged as a new and promising research area. However, MCNs service provisioning aspects, which are the focus of this paper, have not yet been addressed. This work identifies and analyzes the high level architectural alternatives for service provisioning using the SIP servlets framework. Our choice of the SIP servlet framework is motivated by the fact that SIP is currently being considered for the signaling protocol in integrated 3G/MANETs. We conclude that the most interesting options for the 3G network operator are an architecture that enables the invocation of 3G services by MANET users and an architecture that enables the execution of MANET services in 3G The first alternative has the advantage of extending 3G coverage and speeding up the service execution process while the second one has the benefit of providing to MANET users a reliable environment with powerful resources for service execution. This paper also identifies the research issues related to these two alternatives.

Emergency sessions are the most fundamental and critical services offered by telecommunications networks. They require preferential treatment over regular sessions and this is achieved with QoS and resource management techniques. An IMS emergency service architecture has been proposed by 3GPP. However, this solution only provides preferential treatment to public-initiated emergency communications. It does not offer any special treatment to mission critical calls, PSAP callbacks, and urgent communications among citizens. Furthermore, the preferential treatment offered does not provide public-initiated emergency sessions with a prioritized access to the resources at the transport layer. This may lead to unacceptable emergency sessions' setup delays and even emergency sessions failures when there is a strong contention for transport resources. This paper tackles these issues by extending the existing 3GPP architecture. We introduce new QoS profiles for emergency sessions, and propose mechanisms for supporting them. We have also built a proof of concept prototype. Its main features are presented.

Safeguarding patientspsila private information is one of the most challenging issues in the design and implementation of modern e-Health systems. Recent advances in Hippocratic Databases (HDB) show a promising direction towards the enforcement of privacy policies in e-Health systems. This paper tackles issues in applying the HDB design to e-Health systems. More specifically, we design an architecture for integrating APPEL preferences with HDB; we extend the original HDB design to support fine-grained privacy authorizations demanded by patients; we adapt the design to a multi-dimensional model; we also propose a design for hierarchical authorizations. Finally, we discuss implementation issues and justify our designs with experimental results.

Emergency services represent one of the fundamental services offered by the IP multimedia subsystem (IMS). Currently, these services rely on a limited range of contextual information (mainly location). A richer set of contextual information could be exploited to provide enhanced emergency services and lead to more efficient emergency operations. In this paper, we propose an extension of the 3GPP IMS emergency service architecture for the provision of enhanced, context-aware emergency services. The 3GPP presence framework is leveraged and extended to realize the information management aspects of the architecture. Furthermore, a proof-of-concept prototype, showcasing an enhanced emergency service scenario, is presented.

Wireless Sensor Networks (WSN) are made up of small devices that can sense context information (e.g. space, physiology, and environment). The IP Multimedia System (IMS) aims at the convergence of Internet and cellular networks. It enables the delivery of multimedia services to end-users. Integrating the sensing capabilities of WSN in the IP multimedia subsystem will open the door to a wide range of novel multimedia services. This paper proposes a presence based architecture for the integration, focusing on how the information is conveyed from the WSN to the presence infrastructure (i.e the inbound interface). Presence is an integral part of IMS. It enables the distribution of end-user presence information (e.g. location, availability), a sub-set of context information, to interested parties, generally applications. We introduce the architecture and elaborate some of the required extensions to the 3GPP presence service. The proof of concept prototype is also described.

Ambient networks is a new networking concept for beyond 3G. An ambient network is defined as one or more network nodes or devices that share a common network control plane. Network composition is a core concept of ambient networks. It requires the composition of the different registries hosted by the composing ambient networks. These registries may be heterogeneous. Entities in a given network may also need to access information hosted by a registry in another network. This makes the problem of information discovery and publication after composition very challenging. This paper proposes a solution based on an overlay architecture. We introduce the functional entities of the overlay architecture; present the procedures and messages related to the publication and discovery of information and describe the implementation of a proof-of-concept prototype based on JXTA, a middleware commonly used in peer-to-peer settings.

Ambient networks refer to a new networking concept for beyond 3G. They use automatic network composition to enable dynamic and instantaneous inter- working between heterogeneous networks on demand. Ambient networks can host several registries (e.g. management information bases, context information bases). When they autonomously compose, the hosted registries have to follow suit and compose. This paper focuses on the issues related to the autonomous composition of registries when ambient networks compose. We identify a set of requirements and propose a general architecture for autonomic composition. We also discuss cursorily information discovery after composition.

Conferencing is an important category of applications that includes very popular applications such as audio/video conferencing, distance learning and multiparty games. It comprises two main components: signaling and media handling. Conferencing in mobile ad hoc networks (MANETs) remains an uphill task due to the special characteristics of these networks. This paper focuses on the media handling aspects of conferencing. It proposes a novel architecture for controlling media mixers. The architecture is based on Megaco, an approach for controlling media mixers in traditional networks. We present it in terms of functional entities, primitives and procedures. Simulation results are also included.

Service differentiation is an active topic in 3G networks, which aim at supporting a diversity of IP multimedia services (with different QoS requirements) and users (establishing sessions with different levels of importance). In this paper, we propose a network level call differentiation scheme in IMS-based 3G networks. This scheme defines three new classes of calls offering different priorities/guarantees to the user. Service differentiation is achieved at the session signaling level by relying on a context-aware resource allocation strategy. An extension to the 3GPP IMS architecture is proposed to realize the service differentiation scheme and a proof-of-concept prototype is built using SIP and COPS as implementation technologies. Unlike other signaling level schemes, the system proposed here offers flexible QoS negotiation mechanisms to the user, provides preferential treatment at the beginning and during sessions, and takes into consideration the characteristics of the multimedia, multiparty, service environment offered by 3G networks.

Ambient Networks (AN) is a new networking concept for beyond 3G. Network composition is a core concept of AN. It provides dynamic cooperation between heterogeneous networks. Each ambient network can host several registries. When the networks compose, the registries also have to compose. This composition is based on a composition agreement that must be negotiated between the different parties involved. This paper presents a framework for dynamic negotiation of an agreement for the composition of registries. It presents the framework principles and a template for the composition agreement proposals, and describes the main steps of the negotiation. It also describes the negotiation protocol (i.e. entities, messages and state diagrams). We have validated our protocol using SPIN, a software tool for simulating and validating distributed systems behavior. The process and the results are discussed.

Quality of service (QoS) support in Web services plays a great role for the success of this emerging technology. In this paper, we present a QoS broker-based architecture for Web services. The main goal of the architecture is to support the client in selecting Web services based on his/her required QoS. To achieve this goal, we propose a two-phase verification technique that is performed by a third party broker. The first phase consists of syntactic and semantic verification of the service interface description including the QoS parameters description. The second phase consists of applying a measurement technique to compute the QoS metrics stated in the service interface and compares their values with the claimed one. This is used to verify the conformity of a Web service from the QoS point of view (QoS testing). A methodological approach to generate QoS test cases, as input to QoS verification is used. We have implemented a prototype that includes the verification and certification components of the broker. We performed experiments to evaluate the importance of verification and certification features in the selection process using real Web services.

In this paper we propose a new architecture for media handling in ad-hoc peer-to-peer networks. The architecture is distributed with two steps in the mixing operation. Our system is composed of two levels of peers. The high level is formed by peers, which do mixing and are called mixers. Each mixer is dedicated to a number of peers belonging to the second level. Synchronization of mixers is important to deliver media streams with proper ordering and timing. We propose a distributed algorithm based on logical clocks to synchronize mixers. The two main advantages of our architecture are scalability and the limited number of mixers in end-to-end path. This second feature guarantees rapid delivery of streams. We have built a proof of concept prototype and compared the performance results with the hierarchical mixing architecture.

Scenario-driven requirement specifications are widely used to capture and represent functional requirements. Use case maps (UCM) is being standardized as part of the user requirements notation (URN), an addition to ITU-T's family of languages. UCM models allow the description of functional requirements and high-level designs at early stages of the development process. Recognizing the importance of having a well defined semantic, we propose, in this paper, a concise and rigorous formal semantics for use case maps, defined in terms of multi-agent abstract state machines. The proposed formal semantics addresses UCM's operational semantics and provides a sound basis for executing UCM specifications using simulation tools and supporting formal verification.

Multiparty sessions are the basis of a wealth of applications. Some examples are audio/video conferencing, distance learning and gaming. Peer-to-peer ad hoc networks are now emerging. They are useful in a wide range of application scenarios in personal, commercial, public and military environments. Very little is known today on how to handle multiparty sessions in these new networks. This paper proposes a novel signaling system for multiparty sessions in peer-to-peer ad hoc networks. The architecture relies on clustering. Requirements are derived and new principles are proposed. The principles are implemented as extensions to the session initiation protocol (SIP). Extending SIP enables easy interworking with conventional third generation telecommunication networks. The implementation is presented. We have also built a prototype, using JXTA, a middleware for peer-to-peer. The prototype is described with the measurements we have made.

Real-time systems interact with their environment using time constrained input/output signals. Examples of real-time systems include patient monitoring systems, air traffic control systems, and telecommunication systems. For such systems, a functional misbehavior or a deviation from the specified time constraints may have catastrophic consequences. Therefore, ensuring the correctness of real-time systems becomes necessary. Two different techniques are usually used to cope with the correctness of a software system prior to its deployment, namely, verification and testing. In this paper, we address the issue of testing real-time software systems specified as a timed input output automaton (TIOA). TIOA is a variant of timed automaton. We introduce the syntax and semantics of TIOA. We present the potential faults that can be encountered in a timed system implementation. We study these different faults based on TIOA model and look at their effects on the execution of the system using the region graph. We present a method for generating timed test cases. This method is based on a state characterization technique and consists of the following three steps: First, we sample the region graph using a suitable granularity, in order to construct a subautomaton easily testable, called grid automaton. Then, we transform the grid automaton into a nondeterministic timed finite state machine (NTFSM). Finally, we adapt the generalized Wp-method to generate timed test cases from NTFSM. We assess the fault coverage of our test cases generation method and prove its ability to detect all the possible faults. Throughout the paper, we use examples to illustrate the various concepts and techniques used in our approach.

It is well known that the tests and diagnostics influence greatly communication software reliability. The testability and the easiness of the diagnostic process of communication software are becoming major concerns of the design community. The fault detection and the fault localization problems are strongly related issues. The ease of diagnostics can be seen as a criterion of testability; it is in fact characterized by specific requirements at the design level. We make a clear link between these two issues and we study the influence of some testability factors on the diagnostic activity. We present our results and hints on "diagnosability" in the context of a finite state machine model.

In this paper, we analyse the statistical data sets of several MPEG encoded videos and propose a model of the elements of a scene. The proposed model permits the characterisation of the elements of the stream scenes. The model can be used to allocate bandwidth dynamically on a scene basis and will result in a high capacity gain while guaranteeing the same and even better QoS. This model is particularly suited for MPEG encoded VBR traffic in wireless ATM networks.

The World-Wide Web has been a remarkably successful system for distributing hypertext documents. The basic model for Web interaction is that a client requests a page of data which can include images and hyperlinks within it. This interaction model is inadequate for real-time multimedia (MM) applications, since the Web and its associated set of protocols, e.g. HTTP, do not support the real-time transfer of the continuous media (Audio/Video). Several solutions have been proposed to support real-time playout of continuous media via the Web, e.g. Netscape. Most of these solutions do not provide means to the user to negotiate the desired presentation quality (in terms of quality of service (QoS) parameters settings); even the proposals that provide QoS negotiation (more generally QoS management) are used in a rather static manner, that is, the video/audio servers are a priori known. The authors propose to integrate in the WWW a dynamic QoS management approach that allows (1) the user to negotiate the desired QoS; and (2) and to select the "best" video/audio server which might support the user requirements. This activity is based on the general structure of multimedia documents and associated QoS parameters, called meta-data, which they developed under an ongoing CITR project. The main objective of the paper is to integrate meta-data associated with MM document in WWW e.g. Netscape; this will allow one to use dynamic QoS management protocols.

Real time reactive systems interact with their environment, using inputs and outputs, within specified time constraints. For such systems, a functional misbehavior or a deviation from the specified time constraints may have catastrophic consequences. Therefore, ensuring the correctness of real time systems becomes very important. We introduce the potential faults which can be encountered in a timed system implementation. We adapt an existing test cases generation technique, based on state characterization set, to generate timed test cases from a timed system specification. We model a timed system with a Timed Input Output Automaton (TIOA), which is a variant of the Alur and Dill model (R. Alur and D. Dill, 1994). In order to generate the timed test suite, the TIOA is first transformed into a Nondeterministic Timed Finite State Machine (NTFSM) with a given granularity. We illustrate our method with an example.

Scenarios as partial behavior description, are used more and more to represent users requirements, and to conduct software engineering. The paper examines automatic generation of specifications from requirements. This is a crucial step when accuracy is desired in the requirement engineering process. Automatic construction of specifications from scenarios reduces to the merging of partial behaviors into global specifications, such that these specifications can reproduce them. The paper presents an incremental algorithm that synthesizes timed automata from scenarios with timing constraints. The algorithm is based on a formalism developed for scenarios. It uses operations semantics, and a mapping between concepts of scenarios, and those of the theory of timed automata.

We propose an efficient algorithm for constructing optimized protocol converters to achieve interoperability between heterogeneous computer networks. This method first generates constraints from existing protocols and imposes them to channel specifications, which removes message sequences of the channel specifications that do not contribute to system progress. Then, an optimized converter is generated from a given deterministic service specification, the two protocol specifications and the modified channel specifications. The observation equivalence is used to compare the service specification and the internetworking system. Compared with related works reported by Calvert and Lam (1989), our method has two advantages: (1) it generates an optimized converter; and (2) it needs less computation.

In protocol engineering, a common approach for system design and implementation is to verify if an implementation specification (or any lower level specification) satisfies its service specification. If an implementation specification does not satisfy its service specification, it is necessary to find out the faults and correct them. In this paper, we present an efficient algorithm for verifying whether an implementation satisfies its service specification related by the testing equivalence and the reduction relation, and generating diagnostic information if an implementation does not satisfy its service specification, based on the transformation of the service specification into a special deterministic machine, called refusal graph, and the coupled product of the refusal graph and the implementation.

The authors propose a generalized diagnostic algorithm for the case where more than one fault (output or transfer) may be present in one of the transitions of a deterministic system represented by a set of communicating finite state machines (CFSMs). Such an algorithm localizes the faulty transition in the distributed system once the fault has been detected. It generates, if necessary, additional diagnostic test cases which depend on the observed symptoms and which permit the location of the detected faults. The algorithm guarantees the correct diagnosis of any single or double fault (output and/or transfer) in at most one of the transitions of a deterministic system which is represented by a set of communicating FSMs. A simple example is used to demonstrate the functioning of the different steps of the proposed diagnostic algorithm.>

The authors propose a generalized diagnostic algorithm for the case where more than one fault (output and/or transfer) may be present in the transitions of a system represented by a deterministic finite state machine (FSM). If existing faults are detected, this algorithm permits the generation of a minimal set of diagnoses, each of which is formed by a set of transitions (with specific types of faults) suspected of being faulty. The occurrence in an implementation of all the faults of a given diagnosis allows the explanation of all observed implementation outputs. The algorithm guarantees the correct diagnosis of certain configurations of faults (output and/or transfer) in an implementation, which are characterized by a certain type of independence of the different faults. The authors also propose an approach for selecting additional test cases, which allows the reduction of the number of possible diagnoses. A simple example is used to demonstrate the different steps of the algorithm.>

It is noted that the evolution of specifications is necessary to accommodate the evolution of requirements and design decisions during the software development and maintenance process. The authors are concerned with formal description techniques that allow the development of executable specifications, especially executable object-oriented specifications of distributed systems. They propose a two-level model for the evolution of large object-oriented specifications. The first level deals with the dynamic modification of types (classes) while the second level deals with the modification of modules. To allow for dynamic modification of types and modules, the authors have developed a reflection-based technique using meta-objects in which the modification operations are defined. In their approach, they have defined a set of structural and behaviour constraints to ensure the specification consistency after its modification at both levels.>

The authors explore a testing approach where the concern for selecting the appropriate test input provided to the implementation under test (IUT) is separated as much as possible from the analysis of the observed output. Particular emphasis is placed on the analysis of the observed interactions of the IUT in order to determine whether the observed input/output trace conforms to the IUT's specification. The authors consider this aspect of testing with particular attention to testing of communication protocol implementations. Various distributed test architectures are used for this purpose, where partial input/output traces are observable by local observers at different interfaces. The error-detection power of different test configurations is determined on the basis of the partial trace visible to each local observer and their global knowledge about the applied test case. The automated construction of trace analysis modules from the formal specification of the protocol is also discussed. Different transformations of the protocol specification may be necessary to obtain the reference specification, which can be used by a local or global observer for checking the observed trace. Experience with the construction of an arbiter for the OSI (open systems interconnection) transport protocol is described.>