Radio-frequency identification (RFID) has been applied widely in applications such as supply chain visibility, pharmaceutical track and trace, etc. The standards body EPCglobal defines various interfaces in the electronic product code (EPC) network architecture to facilitate the interoperability of different applications. Logical reader is a concept defined in the application level events (ALE) specification to shield applications from knowing the physical device infrastructure. This paper proposes a new approach to the logical reader abstraction, which is defined using spatial zones and implemented by combining mobile, passive RFID with positioning technologies, such as active RFID. This hybrid approach exploits the best benefits of passive and active RFID, while maintaining compatibility with EPC standards for accessing logical readers via ALE. An evaluation of competing approaches is presented. The study shows that this spatial-zone-based design enables fine grain tracking of assets at lower infrastructure cost as compared to existing techniques (e.g., using active RFID only). The study also analyzes the accuracy of the proposed approach using numerical simulation. The results show that it outperforms a widely used chokepoint-based solution under realistic operating conditions.

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.

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.

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.

article Free AccessType-extension type test can be performed in constant time Author: Norman H. Cohen T. J. Watson Research Center, Yorktown Heights, NY T. J. Watson Research Center, Yorktown Heights, NYView Profile Authors Info & Claims ACM Transactions on Programming Languages and SystemsVolume 13Issue 4Oct. 1991 pp 626–629https://doi.org/10.1145/115372.115297Published:01 October 1991Publication History 63citation439DownloadsMetricsTotal Citations63Total Downloads439Last 12 Months29Last 6 weeks1 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

CallsThe well-known recursive procedures to compute a given element of the Fibonacci series, to compute a binomial coefficient, and to solve the Towers of Hanoi puzzle define redundant computations.An invocation generally leads to many recursive calls with the same argument value.Such a redundant recursive procedure can be transformed into a nonredundant one when the operations appearing in the procedure have certain algebraic properties.The transformed programs avoid redundancy by saving exactly those intermediate results that will be needed again later in the computation.

Many well-known functions are computed by interpretations of the recursion schemaprocedure f(x) ;if p(x)then return a(x)else return b(x,f(c1(x)),…,f(cn(x)))Some of these interpretations define redundant computations because they lead to multiple calls on f with identical argument values. The existence and nature of the redundancy depend on properties of the functions ci. We explore four sets of assumptions about these functions. We analyze directed acyclic graphs formed by merging the nodes of the computation tree for f(x) which are known to be equal for each set of assumptions. In each case there is a transformed program which computes f(x) without redundancy, provided that certain additional assumptions about p, a, and the ci are satisfied. The transformed programs avoid redundancy by saving exactly those intermediate results which will be needed again later in the computation. These programs are all valueless recursive procedures which leave intermediate and final results in specified global locations; in each case recursion can be eliminated without use of a stack. We compare the storage requirements of the transformed programs, discuss the applicability of these transformations to an automatic program improvement system, and present a general criterion for establishing the existence of redundancy.