Norman H. Cohen

Web browsing in a wireless environment: disconnected and asynchronous operation in ARTour Web Express

In a previous paper [l], we described ARTour Web Express, a software system that makes it possible to run World Wide Web applications over wide-area wireless nehvorks. Our earlier paper discussed how our system significantly reduces user cost and response time during online browsing over wireless communications links. Even with these savings, however, users may experience slow performance. This is a result of the inherent delay of wireless communication coupled with congestion in the Internet and Web servers, which cannot be masked Corn users under the synchronous request/response model of browsing. Furthermore, disconnection - both voluntary and involuntary - is common in the mobile environment, and the standard browsing model provides no support for disconnected operation. This paper describes how ARTour Web Express has been enhanced to support both disconnected and asynchronous operation.

Composing pervasive data using iQL

The emergence of pervasive networked data sources, such as Web services, sensors, and mobile devices, enables context-sensitive, mobile applications. We have developed a programming model for writing such applications, in which entities called composers accept data from one or more sources, and act as sources of higher-level data. We have defined and implemented a nonprocedural language, iQL, specifying the behavior of composers. An iQL programmer expresses requirements for data sources rather than identifying specific sources; a runtime system discovers appropriate data sources, binds to them, and rebinds when properties of data sources change. The language has powerful operators useful in composition, including operators to generate, filter, and abstract streams of values.

iQueue: a pervasive data composition framework

There will soon be a huge number of data sources accessible to applications across the Internet. These include Web services, personal devices such as cellular phones and cars, and sensors measuring physical phenomena. New classes of data-composition applications can exploit this data. However, the data is diverse, voluminous, and often rapidly changing. The sources of data can be mobile, distributed, and failure-prone. Without system support, applications that use this kind of data are difficult to write. The iQueue data composition framework provides system support for data composition, thereby making the task of writing applications easier.

Enterprise data access from mobile computers: an end-to-end story

Currently, hand-held and palmtop computers are widely used for personal information management. In the near future, they will also be used to access enterprise data. There are however, numerous technical challenges in enabling an end-to-end system that provides enterprise data access from mobile computers. The challenges include heterogeneity, various resource constraints, scalability and security. In this paper, we describe the design and implementation of the Mobile Data Synchronization Service (MDSS), an end-to-end system that provides enterprise data access from mobile computers. Specifically, we address the heterogeneity of devices and data sources, the memory and power constraints of devices, the poor quality of communication and the need for scalability. Our system achieves interoperability and solves the key technical challenges related to enterprise data access from mobile computers.

EventScript: an event-processing language based on regular expressions with actions

EventScript is a simple but powerful language for programming reactive processes. A stream of incoming events is matched against a regular expression. Actions embedded within the regular expression are executed in response to the matching of patterns of events. These actions include assigning computed values to variables and emitting output events. The definition of EventScript presented a number of novel and interesting language-design choices. EventScript has an efficient implementation, and has been used in a development environment for complex event-based applications. We have used EventScript to program both small examples and large industrial applications. Readers of EventScript programs find them easy to understand, and are comfortable with the familiar model of matching regular expressions.

Descriptive naming of context data providers

Much context data comes from mobile, transient, and unreliable sources. Such resources are best specified by descriptive names identifying what data is needed rather than which source is to provide it. The design of descriptive names has important consequences, but until now little attention has been focused on this problem. We propose a descriptive naming system for providers of context data that provides more flexibility and power than previous naming systems by classifying data providers into “provider kinds” that are organized in an evolving hierarchy of subkinds and superkinds. New provider kinds can be inserted in the hierarchy not only as subkinds, but also as superkinds, of existing provider kinds. Our names can specify arbitrary boolean combinations of arbitrary tests on data-source attributes, yielding expressive power not found in naming schemes based on attribute matching.

DRIVE: a tool for developing, deploying, and managing distributed sensor and actuator applications

This paper introduces Distributed Responsive Infrastructure-Virtualization Environment (DRIVE), a tool that provides both an integrated development environment (IDE) and an execution environment and thus supports the entire life cycle of sensor/actuator applications. Developers are only responsible for implementing the core event-handling logic, whereas DRIVE generates the necessary code for message passing and invocation, thus reducing the development skills required. The development methodology, which is component based and model driven, separates the solution model, which captures the business logic, from the deployment model, which reflects the physical computing infrastructure. This allows the administrators to configure and deploy applications on various infrastructure topologies. To illustrate the benefits of DRIVE, we present an example application, dock-door receiving, and show the ways in which DRIVE supports the modeling and development of the application logic and the multiphase deployment of the resulting application in a production environment.

A Java Framework for Mobile Data Synchronization

An industry consortium has developed a Java framework for peer-to-peer synchronization of object stores on mobile devices. A device may issue or service requests for synchronization. Successful synchronization leaves replica stores in identical states. The framework is designed to accommodate memory-limited devices and unreliable and expensive connections. Stored objects belong to application classes with methods that are invoked by the framework during synchronization, for example to resolve update conflicts.

Parallel Quicksort: an exploration of concurrent programming in Ada

We develop an Ada Quicksort program which sorts disjoint subsections of an array concurrently. This exercise reveals pitfalls which Ada programmers using tasks must strive to avoid.

Extending SOA/MDD to Sensors and Actuators for Sense-and-Respond Business Processes

While the practice of service oriented architecture (SOA) and model-driven development (MDD) has brought efficiency gains to software development, building responsive, scalable business applications enabled by distributed sensor and actuator (S&A) infrastructure remains challenging, often involving extensive effort and skill. The results are typically one-of-a-kind, difficult to replicate or modify for different environments, and brittle in the face of changes to the physical plant and equipment. This paper examines the challenges presented by distributed S&A infrastructure in the context of business information systems, and introduces an architecture that applies SOA/MDD methodologies to the modeling, development, deployment, and management of S&A systems. In particular, the architecture focuses on the separation of concerns between logical application development and infrastructure capability management, and the support of component assembly with an event-based programming model. The paper then briefly describes a prototype implementation of the architecture, including integrated tooling and runtime support, and illustrates its role relative to existing business process modeling, integration and execution environments with examples based on industry applications.Although some relatively mature products and systems about Dynamic service composition are proposed, their manipulations are mostly not trivial and intuitive for the common users. Therefore, this paper proposes a dataflow driven dynamic service composition architecture aiming at astronomy applications, to simplify the requirements for users to compose a service. The architecture utilizes Dataflow Driven conception to discover an Original Topology Graph, which includes the final composite service with the shortest length and good parallel structure, and uses a Converse Composition algorithm to ascertain the final result quickly. This architecture is applied in the PMGrid prototype for astronomy data processing, and the experiment results show the architecture satisfies the parallelism and asynchrony in distributed system, avoids manual errors, increases the service configuring efficiency, provides the composite service with better structure to increase the executing parallelism, and finally improve the scientific discovery.