An extensible architecture for run-time monitoring of conversational web services

Trust in Web services will be greatly enhanced if these are subject to run-time verification, even if they were previously tested, since their context of execution is subject to continuous change; and services may also be upgraded without notifying their consumers in advance. Conversational Web services introduce added complexity when it comes to run-time verification, since they follow a conversation protocol and they have a state bound to the session of each consumer accessing them. Furthermore, conversational Web services have different policies on how they maintain their state. Access to states can be private or shared; and states may be transient or persistent. These differences must be taken into account when building a scalable architecture for run-time verification through monitoring. This paper, building on a previously proposed theoretical framework for run-time verification of conversational Web services, presents the design, implementation and validation of a novel run-time monitoring architecture for conversational services, which aims to provide a holistic monitoring framework enabling the integration of different verification tools. The architecture is validated by running a sequence of test scenarios, based on a realistic example. The experimental results revealed that the monitoring activities have a tolerable overhead on the operation of a Web service

Reliable Messaging to Millions of Users with MigratoryData

Web-based notification services are used by a large range of businesses to selectively distribute live updates to customers, following the publish/subscribe (pub/sub) model. Typical deployments can involve millions of subscribers expecting ordering and delivery guarantees together with low latencies. Notification services must be vertically and horizontally scalable, and adopt replication to provide a reliable service. We report our experience building and operating MigratoryData, a highly-scalable notification service. We discuss the typical requirements of MigratoryData customers, and describe the architecture and design of the service, focusing on scalability and fault tolerance. Our evaluation demonstrates the ability of MigratoryData to handle millions of concurrent connections and support a reliable notification service despite server failures and network disconnections

A Framework for QoS-aware Execution of Workflows over the Cloud

The Cloud Computing paradigm is providing system architects with a new powerful tool for building scalable applications. Clouds allow allocation of resources on a "pay-as-you-go" model, so that additional resources can be requested during peak loads and released after that. However, this flexibility asks for appropriate dynamic reconfiguration strategies. In this paper we describe SAVER (qoS-Aware workflows oVER the Cloud), a QoS-aware algorithm for executing workflows involving Web Services hosted in a Cloud environment. SAVER allows execution of arbitrary workflows subject to response time constraints. SAVER uses a passive monitor to identify workload fluctuations based on the observed system response time. The information collected by the monitor is used by a planner component to identify the minimum number of instances of each Web Service which should be allocated in order to satisfy the response time constraint. SAVER uses a simple Queueing Network (QN) model to identify the optimal resource allocation. Specifically, the QN model is used to identify bottlenecks, and predict the system performance as Cloud resources are allocated or released. The parameters used to evaluate the model are those collected by the monitor, which means that SAVER does not require any particular knowledge of the Web Services and workflows being executed. Our approach has been validated through numerical simulations, whose results are reported in this paper

Extending the Internet of Things to the future Internet through IPv6 Support

Emerging Internet of Things (IoT)/Machine-to-Machine (M2M) systems require a transparent access to information and services through a seamless integration into the Future Internet. This integration exploits infrastructure and services found on the Internet by the IoT. On the one hand, the so-called Web of Things aims for direct Web connectivity by pushing its technology down to devices and smart things. On the other hand, the current and Future Internet offer stable, scalable, extensive, and tested protocols for node and service discovery, mobility, security, and auto-configuration, which are also required for the IoT. In order to integrate the IoT into the Internet, this work adapts, extends, and bridges using IPv6 the existing IoT building blocks (such as solutions from IEEE 802.15.4, BT-LE, RFID) while maintaining backwards compatibility with legacy networked embedded systems from building and industrial automation. Specifically, this work presents an extended Internet stack with a set of adaptation layers from non-IP towards the IPv6-based network layer in order to enable homogeneous access for applications and services

BUILDING A DISTRIBUTED TRUST MODEL OF RESTFUL WEB SERVICES FOR MOBILE DEVICES

As of 2011, there were about 5,981 million mobile devices in the world [1] and there are 113.9 million mobile web users in 2012 [2]. With the popularity of web services for mobile devices, the concern of security for mobile devices has been brought up. Furthermore, with more and more cooperation of organizations, web services are now normally involved with more than one organization. How to trust coming requests from other organizations is an issue. This research focuses on building a trust model for the web services of mobile devices. It resolves the issues caused by mobile devices being stolen, lost, users abusing privileges, and cross-domain’s access control. The trust model is distributed in each node of the web servers. The trust value is calculated for every incoming request to decide whether the request should be served or not. The goals of the trust model are 1) flexible; 2) scalable; 3) lightweight. The implementation is designed and accomplished with the goals in mind. The experiments evaluate the overhead for the trust module and maximum capacity of the system

SNAP, Crackle, WebWindows!

We elaborate the SNAP---Scalable (ATM) Network and (PC) Platforms---view of computing in the year 2000. The World Wide Web will continue its rapid evolution, and in the future, applications will not be written for Windows NT/95 or UNIX, but rather for WebWindows with interfaces defined by the standards of Web servers and clients. This universal environment will support WebTop productivity tools, such as WebWord, WebLotus123, and WebNotes built in modular dynamic fashion, and undermining the business model for large software companies. We define a layered WebWindows software architecture in which applications are built on top of multi-use services. We discuss examples including business enterprise systems (IntraNets), health care, financial services and education. HPCC is implicit throughout this discussion for there is no larger parallel system than the World Wide metacomputer. We suggest building the MPP programming environment in terms of pervasive sustainable WebWindows technologies. In particular, WebFlow will support naturally dataflow integrating data and compute intensive applications on distributed heterogeneous systems