Service Verification Research Articles

UK extended Medical Assessment Programme for ex-service personnel: the first 150 individuals seen

Aims and methodTo describe an interim service set up to examine the breadth of UK ex-service personnel's concerns in relation to their mental health and military service and provide a record of the first 150 individuals assessed following conformation of military service and examination of all available military and civilian medical records.ResultsThe majority of attendees were White male ex-soldiers. Average age, service and time to assessment were 44.5, 15.8 and 11.7 years respectively. Two-thirds were receiving help from the National Health Service and ex-service nongovernmental organisations. Rates of post-traumatic stress disorder were similar to previous UK studies. Obsessional symptoms were of relevance to the clinical presentation in a third. Fabrication and/or exaggeration occurred in about 10%.Clinical implicationsThe spread of diagnoses and delay in help-seeking are similar to civilians. The link between mental disorders and military service is seldom straightforward and fabrication or exaggeration is difficult for civilians to recognise. Verification and contextualisation of service using contemporaneous service medical records is important given the possible occupational origin of mental health conditions.

Simulation of human behaviours for the validation of Ambient Intelligence services: A methodological approach

An Ambient Intelligence (AmI) system is a pervasive system in which services have some intelligence in order to smoothly interact with users immersed in the environment. Users are the main entity in AmI systems. Thus, the services are user-centred with an adaptive interaction that provides users with more personalized facilities in a non-intrusive way. The deployment of AmI services is a hard task, especially when the system includes complex users' behaviours or complex deployments in terms of the devices and software participating at the system. Since one of the intrinsic requirements in these services is smooth interaction with users, the user, or at least a model of the user, should be incorporated in the development process. This makes the process of verification and validation of such services quite difficult. This paper proposes the use of Agent Based Social Simulation for a quick and feasible validation of AmI systems. Simulation in the first stages enables easy validation of the services before real environment deployment. The main challenge in this approach is how to simulate humans with realistic behaviours. In this paper, Social Simulation (SS) is used to tackle this problem. Specifically, this paper presents a methodology for the validation of AmI systems by SS. The realistic modelling of users and its validation are key elements of this process and involve challenges that the techniques proposed here are able to deal with. A real application example which shows the level of reality reached in the users' models and the benefits of the methodology is presented in this paper.

An Efficient and Secure Service Discovery Protocol for Ubiquitous Computing Environments

Recently, numerous service discovery protocols have been introduced in the open literature. Unfortunately, many of them did not consider security issues, and for those that did, many security and privacy problems still remain. One important issue is to protect the privacy of a service provider while enabling an end-user to search an alternative service using multiple keywords. To deal with this issue, the existing protocols assumed that a directory server should be trusted or owned by each service provider. However, an adversary may compromise the directory server due to its openness property. In this paper, we suggest an efficient verification of service subscribers to resolve this issue and analyze its performance and security. Using this method, we propose an efficient and secure service discovery protocol protecting the privacy of a service provider while providing multiple keywords search to an end-user. Also, we provide performance and security analysis of our protocol.

Boater Safety: Communicating Weather Forecast Information to High-Stakes End Users

Abstract Recreational boaters in the Pacific Northwest understand that there is uncertainty inherent in deterministic forecasts as well as some of the factors that increase uncertainty. This was determined in an online survey of 166 boaters in the Puget Sound area. Understanding was probed using questions that asked respondents what they expected to observe when given a deterministic forecast with a specified lead time, for a particular weather parameter, during a particular time of year. It was also probed by asking respondents to estimate the number of observations, out of 100 or out of 10, that they expected to fall within specified ranges around the deterministic forecast. Almost all respondents anticipated some uncertainty in the deterministic forecast as well as specific biases, most of which were born out by an analysis of local National Weather Service verification data. Interestingly, uncertainty and biases were anticipated for categorical forecasts indicating a range of values as well, suggesting that specifying numeric uncertainty would improve understanding. Furthermore, respondents’ answers suggested that they expected a high rate of false alarms among warning and advisory forecasts. Nonetheless, boaters indicated that they would take precautionary action in response to such warnings, in proportions related to the size of boat they were operating. This suggests that uncertainty forecasts would be useful to these experienced forecast consumers, allowing them to adapt the forecast to their specific boating situation with greater confidence.

Analysis of existing remote attestation techniques

ABSTRACTThis paper has been written as a part of the research project that is working towards the implementation of dynamic behavioral attestation for mobile platforms. The motivation behind this paper was to analyze the existing remote attestation techniques in order to figure out their strengths and weaknesses. We have analyzed Integrity Measurement Architecture, Policy‐reduced Integrity Measurement Architecture, Property‐based Attestation, Remote Attestation on Program Execution, Semantic Remote Attestation, Trustable Remote Verification of Web Services, and Model‐based Behavior Attestation. Each of the existing remote attestation techniques was found to be effective in some situations but was found to be infeasible in others. Therefore, a new remote attestation technique is needed, which is platform independent and flexible enough to meet the challenges of today's scalable computing environments. Copyright © 2011 John Wiley & Sons, Ltd.

Specification and Verification of Context-dependent Services

Current approaches for the discovery, specification, and provision of services ignore the relationship between the service contract and the conditions in which the service can guarantee its contract. Moreover, they do not use formal methods for specifying services, contracts, and compositions. Without a formal basis it is not possible to justify through formal verification the correctness conditions for service compositions and the satisfaction of contractual obligations in service provisions. We remedy this situation in this paper. We present a formal definition of services with context-dependent contracts. We define a composition theory of services with context-dependent contracts taking into consideration functional, nonfunctional, legal and contextual information. Finally, we present a formal verification approach that transforms the formal specification of service composition into extended timed automata that can be verified using the model checking tool UPPAAL.

Verification of Time Constraints Consistency on Web Service Composition Based on ETPN

The work of Web Service verification mainly concentrated in testing service functional correctness, the non-functioning attribute description and verification is relatively rare. For the lack of non-functioning attribute service verification, the available time phrase of Web Service is added into the OWL-S model to describe time-attribute, establish the mapping rules and transformation method from OWL-S process model to ETPN, and the available time relation matrix is proposed to verify time constraints consistency based on the ETPN theory, it can help to remove the plan of service composition has time conflict and avoid the waste of Web Service resource.

Modeling Web Service Behavior Based on Workflow Nets and Consume-Produce-Read Nets

To support automated service composition, adaptation and verification, there should be a formal model for web service behavior description. For the sake of accurately representing web service behavior, inspired by workflow nets and consume-produce-read nets, we propose a novel formal model for web service behavior description, which can not only describe the control flow, but also the data flow as well as the communication flow of the web service accurately. The model regards tokens, data and messages as control resources, data resources and communication resources and adopts completely different store-and-fetch strategies for each kind of resources respectively.

Style-based modeling and verification of fault tolerance service oriented architectures

Abstract Service-Oriented Architecture (SOA) is a flexible, loosely coupled and dynamic architecture for developing different distributed systems. Since using this architecture is every day increasing in the design of software systems, creating dependable services in this architecture is one of the main challenges. Considering different QoS levels consisting of non-functional aspects like security, safety; accessibility, etc is necessary for dependable systems. One of these non-functional aspects is fault tolerance. In this paper, in order to have a fault tolerance system, initially SOA core style has been extended using required parameters. Then, different communication and reconfiguration mechanisms of fault tolerance have been developed by graph transformation rules. Finally, the proposed model has been verified using model checking techniques available for graph transformation systems.

Communicating forecast uncertainty: public perception of weather forecast uncertainty

AbstractThe general public understands that there is uncertainty inherent in deterministic forecasts as well as understanding some of the factors that increase uncertainty. This was determined in an online survey of 1340 residents of Washington and Oregon, USA. Understanding was probed using questions that asked participants what they expected to observe when given a deterministic forecast with a specified lead time, for a particular weather parameter, during a particular time of year. It was also probed by asking participants to estimate the number of observations, out of 100, that they expected to fall within specified ranges around the deterministic forecast. Almost all respondents (99.99%) anticipated some uncertainty in the deterministic forecast. Furthermore, their answers suggested that they expected greater uncertainty for longer lead times when the forecasted value deviated from climatic norms. Perhaps most noteworthy was that they expected specific forecast biases (e.g. over‐forecasting of extremes), most of which were not borne out by an analysis of local National Weather Service verification data. In summary, users had well‐formed uncertainty expectations suggesting that they are prepared to understand explicit uncertainty forecasts for a wide range of parameters. Indeed, explicit uncertainty estimates may be necessary to overcome some of the anticipated forecast biases that may be affecting the usefulness of existing weather forecasts. Despite the fact that these bias expectations are largely unjustified, they could lead to adjustment of forecasts that could in turn have serious negative consequences for users, especially with respect to extreme weather warnings. Copyright © 2010 Royal Meteorological Society

WST: a tool supporting timed composite Web Services Model transformation

In this paper we introduce a tool called the Web Service Translation tool (WST), which we are developing to implement a methodology for the design, validation and verification of Web Services with timed restrictions. This methodology works by making several translations, from phase to phase in the software development life cycle, where the system is represented at each phase by XML models. We use XSL Transformations (XSLT), which is a language for transforming XML documents. The purpose of these translations is to generate XML code automatically for a Web Service system and to obtain Web Services description models with Timed Automata for validating and verifying composite Web Services with time restrictions.

Task-execution scheduling schemes for network measurement and monitoring

Measurement is a required process in high performance networks for efficient quality-of-service (QoS) provisioning and service verification. Active measurement is an attractive approach because the measurement traffic injected into the network can be controlled and the measurement tasks can be distributed throughout the network. However, the execution of measurement tasks in common parts of a network may face contention for resources, such as computational power, memory, and link bandwidth. This contention could jeopardize measurement accuracy and affect network services. This contention for limited resources defines a conflict between measurement tasks. Furthermore, we consider two sets of measurement tasks, those used to monitor network state periodically, called periodic tasks, and those for casual measurements issued as needed, called on-demand measurement tasks. In this paper, we propose a novel scheduling scheme to resolve contention for resources of both periodic and on-demand measurement tasks from graph coloring perspective, called ascending order of the sum of clique number and degree of tasks. The scheme selects tasks according to the ascending order of the sum of clique number and conflict task degree in a conflict graph and allows concurrent execution of multiple measurement tasks for high resource utilization. The scheme decreases the average waiting time of all tasks in periodic measurement tasks scheduling. For on-demand measurement tasks, the proposed scheme minimizes the waiting time of inserted on-demand tasks while keeping time space utilization high. In other words, the total time spent on finishing all the tasks is shortened. We evaluate our proposed schemes under different measurement task assignment scenarios through computer simulations, and compare the performance of this scheme with others that also allow concurrent task execution. The simulation results show that the proposed scheme produces effective contention resolution and low execution delays.

TESTING AND FORMAL VERIFICATION OF SERVICE ORIENTED ARCHITECTURES

We examine two open engineering problems in the area of testing and formal verification of internet-enabled service oriented architectures (SOA). The first involves deciding when to formally and exhaustively verify versus when to informally and non-exhaustively test. The second concerns scalability limitations associated with formal verification, to which we propose a semi-formal technique that uses software agents. Finally, we assess how these findings can improve current software quality assurance practices. Addressing the first problem, we present and explain two classes of tradeoffs. External tradeoffs between assurance, performance, and flexibility are determined by the business needs of each application, whether it be in engineering, commerce, or entertainment. Internal tradeoffs between assurance, scale, and level of detail involve the technical challenges of feasibly verifying or testing an SOA. To help decide whether to exhaustively verify or non-exhaustively test, we present and explain these two classes of tradeoffs. Identifying a middle ground between testing and verification, we propose using software agents to simulate services in a composition. Technologically, this approach has the advantage of assuring the quality of compositions that are too large to exhaustively verify. Operationally, it supports testing these compositions in the laboratory without access to source code or use of network resources of third-party services. We identify and exploit the structural similarities between agents and services, examining how doing so can assure the quality of service compositions.

Research on the service-oriented solution for integrating WSN with grid

The idea building Wireless Sensor Networks(WSN) system based on services and working via a uniform interface,referring to Service-Oriented Architecture(SOA),seems an intuitionistic way to integrate WSN with the grid seamlessly.This paper anatomized WSN architecture in forms of services first and presented a formal definition and verification of WSN services combination.Then the integration scheme was discussed,which involved gateway interface and service agent middleware.The scheme not only makes WSN and grid cooperate to meet the application needs by a friendly interface,but also effectively guarantee the QoS of WSN when attached to grids.

A Model-Based Approach to the Verification and Adaptation of WF/.NET Components

This paper presents an approach which supports verification and model-based adaptation of software components and services implemented using Windows Workflow Foundation (WF). First, we propose an abstract description of WF workflows, and we formalise the extraction of Labelled Transition Systems from these workflows. Next, verification and adaptation are applied using respectively model-checking techniques and existing model-based adaptation approaches. Last, we explain how a WF workflow can be generated from an adaptor protocol.

A mechanism for grid service composition behavior specification and verification

Current grid service choreography proposals remain at the descriptive level, without providing any kind of reasoning mechanism to check the compatibility and validity of grid service composition. How to formalize and verify the behavior of the grid service composition is therefore imperative. A novel process algebra, Cpi-calculus (Conditional Pi-calculus), is proposed in this paper. By analyzing the interactive behavior of composite grid services, we present a grid service composition signature. Based on the signature, we construct Interactive Behavior Model (IABM) for grid service composition and specify the interactive behavior using the Cpi-calculus. The case study shows that the mechanism for grid service specification and verification could be the algebraic foundation to be used afterwards in automatic and dynamic composition.

Viewer Identification and Authentication in IPTV using RFID Technique

This paper presents the application of RFID (radio frequency identification) to identify and authenticate the viewer for personalized and interactive services offered by the IPTV (internet protocol television). Main purpose of the setup is to identify and authenticate the viewer, the person who is watching the TV, for parental control, payment services, consumer feedback and input etc. Using RFID reader with IPTV STB (set-top box) for authentication of viewer and service verification results in identifying viewer, using RFID tag wirelessly and at low cost. With RFID service becoming ubiquitous and its application and connectivity with home automation systems, the proposed system is thought to be widely adaptable. This Interactive identification technique also provides reliable security to protect the viewer contents, media and parental control.

Modeling and verification of a telecommunication application using live sequence charts and the Play-Engine tool

We apply the scenario-based approach to modeling, via the language of live sequence charts (LSCs) and the Play-Engine tool to a real-world complex telecommunication service, \({\tt Depannage}\). It allows a user to call for help from a doctor, the fire brigade, a car maintenance service, etc. These kinds of services are built on top of an embedded platform, using both new and existing service components, and their complexity stems from their distributed architecture, the various time constraints they entail, and their rapidly evolving underlying systems. A well known problem in this class of telecommunication applications is that of feature interaction, whereby a new feature might cause problems in the execution of existing features. Our approach provides a methodology for high-level modeling of telecommunication applications that can help in detecting feature interaction at early development stages. We exhibit the results of applying the methodology to the specification, animation and formal verification of the Depannage service.

Verification of Web Services with Timed Automata

In this paper we show how we can use formal methods for describing and analyzing the behavior of Web Services, and more specifically those including time restrictions. Then, our starting point are Web Services descriptions written in WSCI – WSCDL (XML-based description languages). These descriptions are then translated into timed automata, and then, we use a well known tool that supports this formalism (UPPAAL) to simulate and analyze the system behavior. As illustration we take a particular case study, a travel reservation system.

Service-driven inter-domain QoS monitoring system for large-scale IP and DVB networks

There is a growing synergy between well-established Service Providers (SP), Content Providers (CP), and Network Providers (NP), to propose new value-added services, and hence opening new markets to generate further revenues. Meanwhile, the explosive increasing amount of multimedia content to be offered in the Internet and the heterogeneity of the underlying networking technologies demand the provision of new QoS-enabled mechanisms and architecture to efficiently control, manage and monitor the networks. Quality of service monitoring is becoming crucial to SPs for providing quantified QoS-based services and service assurance and to NPs for managing network resources. This paper proposes a framework for large scale inter-domain QoS monitoring in heterogeneous networks including IP and DVB networks that has been developed in the IST-ENTHRONE project of European Commission. One of the main aims is actually to allow high cooperation between different providers while keeping intact the authority, confidentiality, and full control of each provider over its underlying resources. The proposed monitoring framework consists of a layered architecture with two signaling protocols namely an inter-domain monitoring signaling protocol (EQoS-RM), and an intra-domain active measurement signaling protocol (Emon). The proposed QoS monitoring system is service-driven in the sense that it aimed at providing in service verification of QoS performance guarantees for the services offered to the users by the providers. To achieve this, it uses both QoS probes that perform both active and passive monitoring at different levels of abstraction employing node and network wide measurements and application-level perceived quality meters for detecting quality degradation. As such, this framework specifies three types of QoS monitoring components operating at different levels: at network element or node, at network and at service levels. This proposed system also provides monitoring information to NPs in order to assist in managing the operational status of their networks. Design and implementation of the proposed QoS monitoring system is described in this paper. Some experimental assessments of this service-driven QoS monitoring system prove its functioning in terms of accuracy and responsiveness in providing the necessary results.