On consistency maintenance in service discovery

Communication and node failures degrade the ability of a service discovery protocol to ensure Users receive the correct service information when the service changes. We propose that service discovery protocols employ a set of recovery techniques to recover from failures and regain consistency. We use simulations to show that the type of recovery technique a protocol uses significantly impacts the performance. We benchmark the performance of our own service discovery protocol, FRODO against the performance of first generation service discovery protocols, Jini and UPnP during increasing communication and node failures. The results show that FRODO has the best overall consistency maintenance performance

The Performance of a Second Generation Service Discovery Protocol In Response to Message Loss

We analyze the behavior of FRODO, a second generation service discovery protocol, in response to message loss in the network. Earlier protocols, like UPnP and Jini rely on underlying network layers to enhance their failure recovery. A comparison with UPnP and Jini shows that FRODO performs more efficiently in maintaining consistency, with shorter latency, not relying on lower network layers for robustness and therefore functions correctly on a simple lightweight protocol stack

Service and device discovery of nodes in a wireless sensor network

Emerging wireless communication standards and more capable sensors and actuators have pushed further development of wireless sensor networks. Deploying a large number of sensor\ud nodes requires a high-level framework enabling the devices to present themselves and the resources they hold. The device and the resources can be described as services, and in this paper, we review a number of well-known service discovery protocols. Bonjour stands out with its auto-configuration, distributed architecture, and sharing of resources. We also present a lightweight implementation in order to demonstrate that an emerging standards-based device and service discovery protocol can actually be deployed on small wireless sensor nodes

A Taxonomy of Self-configuring Service Discovery Systems

We analyze the fundamental concepts and issues in service discovery. This analysis places service discovery in the context of distributed systems by describing service discovery as a third generation naming system. We also describe the essential architectures and the functionalities in service discovery. We then proceed to show how service discovery fits into a system, by characterizing operational aspects. Subsequently, we describe how existing state of the art performs service discovery, in relation to the operational aspects and functionalities, and identify areas for improvement

A Service Discovery-Enabled LCD Projector Device

The widespread deployment of inexpensive communications technology, computational resources in the networking infrastructure and network-enabled end devices pose a problem for end users: how to locate a particular network service or device out of those accessible. Service providers use Service Discovery Services (SDS) to advertise the descriptions of available or already running services, while clients use SDS to compose queries for locating these services. Service descriptions and queries use the eXtensible Markup Language (XML) to encode vendor specific information and device- or service-specific capabilities as well as the actions addressed to the device or service. This report presents the architecture and implementation of a SDS used to locate enabled LCD projectors and use them for presentation. The presentation service provides all the capabilities to the end user so that he can choose the projector device of his interest and use the graphical user interface to navigate thorough the presentation. The presentation service also has the capability to use more than one projector at a time. We use the Universal Plug and Play suite of protocols to establish the communication between client and the projector device

GRIDKIT: Pluggable overlay networks for Grid computing

A `second generation' approach to the provision of Grid middleware is now emerging which is built on service-oriented architecture and web services standards and technologies. However, advanced Grid applications have significant demands that are not addressed by present-day web services platforms. As one prime example, current platforms do not support the rich diversity of communication `interaction types' that are demanded by advanced applications (e.g. publish-subscribe, media streaming, peer-to-peer interaction). In the paper we describe the Gridkit middleware which augments the basic service-oriented architecture to address this particular deficiency. We particularly focus on the communications infrastructure support required to support multiple interaction types in a unified, principled and extensible manner-which we present in terms of the novel concept of pluggable overlay networks

Context gathering in Ubiquitous Environments: Enhanced Service Discovery

Delivering individualized services that conform to the user’s current situation will form the focus of ubiquitous environments. A description of the networked environment at a semantic level will necessitate contextually oriented knowledge acquisition methods. This then engenders unique challenges for the crucial step of resource discovery. A number of service discovery protocols exist to perform this role. In this paper, we identify the requirements inherent for such an environment and investigate the suitability of the available protocols against these. A suitable candidate solution is proposed with an implementation with semantic extensions and reference points for further enhancements

Programmable Conference Server

Conferencing services for Internet telephony and multimedia can be enhanced by the integration of other Internet services, such as instant messaging, presence notification, directory lookups, location sensing, email and web. These services require a service programming architecture that can easily incorporate new Internet services into the existing conferencing functionalities, such as voice-enabled conference control. W3C has defined the Call Control eXtensible Markup Language (CCXML), along with its VoiceXML, for telephony call control services in a point-to-point call. However, it cannot handle other Internet service events such as presence enabled conferences. In this paper, we propose an architecture combining VoiceXML with our Language for End System Services (LESS) and the Common Gateway Interface (CGI) for multi-party conference service programming that integrates existing Internet services. VoiceXML provides the voice interface to LESS and CGI scripts. Our architecture enables many novel services such as conference setup based on participant location and presence status. We give some examples of the new services and describe our on-going implementation

Privacy and location-aware service discovery for mobile and ubiquitous systems

Wireless networks play a major role in allowing the deployment of ubiquitous distributed systems. In these networks, service discovery should not only allow finding available networked services, but should also take into account the physical proximity of the entities requesting these services. However, physical proximity is not a sufficient criteria for service search and selection, as close attention should be paid to privacy issues. In this paper we present the design issues that should be considered in order to properly support service discovery based on the physical location of clients; these issues are taken into account for the proposal of an architecture for context-aware distributed systems that consider privacy concerns8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

Context-aware Authorization in Highly Dynamic Environments

Highly dynamic computing environments, like ubiquitous and pervasive computing environments, require frequent adaptation of applications. Context is a key to adapt suiting user needs. On the other hand, standard access control trusts users once they have authenticated, despite the fact that they may reach unauthorized contexts. We analyse how taking into account dynamic information like context in the authorization subsystem can improve security, and how this new access control applies to interaction patterns, like messaging or eventing. We experiment and validate our approach using context as an authorization factor for eventing in Web service for device (like UPnP or DPWS), in smart home security