We propose a new design for highly concurrent Internet services, whichwe call the staged event-driven architecture (SEDA). SEDA is intended

this paper, we describe a new information management service called Astrolabe. Astrolabe monitors the dynamically changing state of a collection of distributed resources, reporting summaries of this information to its users. Like DNS, Astrolabe organizes the resources into a hierarchy of domains, which we call zones to avoid confusion, and associates attributes with each zone. Unlike DNS, zones are not bound to specific servers, the attributes may be highly dynamic, and updates propagate quickly; typically, in tens of seconds

Attempts to generalize the Internet's point-to-point communication abstraction to provide services like multicast, anycast, and mobility have faced challenging technical problems and deployment barriers. To ease the deployment of such services, this paper proposes an overlay-based Internet Indirection Infrastructure (i3) that offers a rendezvous-based communication abstraction. Instead of explicitly sending a packet to a destination, each packet is associated with an identifier; this identifier is then used by the receiver to obtain delivery of the packet. This level of indirection decouples the act of sending from the act of receiving, and allows i3 to efficiently support a wide variety of fundamental communication services. To demonstrate the feasibility of this approach, we have designed and built a prototype based on the Chord lookup protocol.

We envision a world of mobile users in an unobtrusive ubiquitous computing environment that couples a computational model, digital media, and virtual representations of the physical world. Hundreds of embedded computers support the information and computational needs of each user. Users, applications, and computing devices move. The location of users and devices drives applications and resource management. Users have anytime/anywhere access to information, the network, and computational resources. Within this world, applications that make effective use of resources to support the activities of users must be simple and efficient to construct. Changes to the physical environment alter the computational model and information space of the users. Similarly, changes to the computational model and information space may alter the physical environment. We call this environment an Active Space. We propose a systems software infrastructure that functions in much the same way as a traditional operating system.

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Abstract: Service discovery is an essential task in pervasive computing environments. Simple and efficient service discovery enables heterogeneous and ubiquitous computing devices and services to be easier to use. Service integration uses services as building blocks to achieve complex services. We describe service discovery and service integration, analyze design issues, and categorize the service discovery protocols. Keywords: Service Discovery, Service Integration, Service Security. In 1991, Mark Weiser coined the term ubiquitous computing, which is also called pervasive computing. In pervasive computing environments, people are surrounded by a variety of computing devices. Those devices communicate with each other and provide information “at a glance ” without our “active attention ” [1]. Presently, PCs, notebooks, cell phones, and Personal Data Assistants (PDAs) surround us. In the near future, additional networked computers, ranging from tiny sensors to extremely dynamic and powerful devices will provide a variety of information and services. It becomes overwhelming to manage these devices, configure different kinds of applications, and dynamically find the available computing services in such pervasive computing environments. Service discovery protocols enable computers to be easier to use. They facilitate interaction between

Computational grids provide mechanisms for sharing and accessing large and heterogeneous collections of remote resources such as computers, online instruments, storage space, data, and applications. Resources are requested ("discovered") by specifying a set of desired attributes. Resource attributes have various degrees of dynamism, from mostly static attributes, such as operating system version, to highly dynamic ones, such as available network bandwidth or CPU load. Another dimension of dynamism is introduced by variable and highly diverse sharing policies: resources are made available to the grid community based on locally defined and potentially changing policies.

Ubiquitous access to sophisticated internet services from diverse end devices across heterogeneous networks requires the injection of additional functionality into the network to handle protocol conversion, data transcoding, and in general bridge disparate network portions. Several researchers have proposed infrastructures for injecting such functionality; however, many challenges remain before these can be widely deployed. CANS is an application-level infrastructure for injecting application-specific components into the network that focuses on three such challenges: (a) efficient and dynamic composition of individual components; (b) distributed adaptation of injected components in response to system conditions; and (c) support for legacy applications and services. The CANS network view comprises applications, stateful services, and data paths built from mobile soft-state objects called drivers. Both services and data paths can be dynamically created and reconfigured: a planning and event propagation model assists in distributed adaptation, and a flexible type-based composition model dictates how new services and drivers are integrated with existing components. Legacy components plug into CANS using an interception layer that virtualizes network bindings and a delegation model. This paper describes the CANS architecture, and a case study involving a shrink-wrapped client application in a dynamically changing network environment where CANS improves overall user experience. 1

this paper, we describe a new information management service called Astrolabe. Astrolabe monitors the dynamically changing state of a collection of distributed resources, reporting summaries of this information to its users. Like DNS, Astrolabe organizes the resources into a hierarchy of domains, which we call zones to avoid confusion, and associates attributes with each zone. Unlike DNS, the attributes may be highly dynamic, and updates propagate quickly; typically, in tens of seconds

This paper presents the architecture and implementation of a secure wide-area Service Discovery Service (SDS). Service providers use the SDS to advertise descriptions of available or already running services, while clients use the SDS to compose complex queries for locating these services. Service descriptions and queries use the eXtensible Markup Language (XML) to encode such factors as cost, performance, location, and device- or service-specific capabilities. The SDS provides a fault-tolerant, incrementally scalable service for locating services in the wide-area. Security is a core component of the SDS: communications are both encrypted and authenticated where necessary, and the system uses a hybrid access control list and capability system to control access to service information. Wide-area query routing is also a core component of the SDS: all information in the system is potentially reachable by all clients