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.

This paper describes software technology that makes it possible to nm Internet World Wide Web applications in wide area wireless networks.Web technology in conjunction with today's mobile devices (e.g., laptops, notebooks, personal digital assistants) and the emerging wireless technologies (e.g., packet radio, CDPD) offer the potential for unprecedented access to data and applications by mobile workers.Yet, the limited bandwidth, high latency, high cost, and poor reliability of today's wireless wide-area networks greatly inhibits (even to the point of being unfeasible) supporting Web applications over wireless networks.WebExpress significantly reduces user cost and response time of wireless communications by intercepting the HITP data stream and performing various optimizations including: flle caching, forms differencing, protocol reduction, and the elimination of redundant HTTP header transmission.This paper describes these optimizations and presents some experiment results.

Conventional database design techniques rely heavily on the designer's skill and experience, which are neither efficient nor effective for large, realistic design problems. A computer design aid can help by storing many design parameters and performing simple preprocessing before design decisions are made. In this paper, we report on the development of such a system.

This paper presents a semantic model and processing language upon which a logical database design tool can be based. The semantic model is invariant with respect to the placement of data items into records or relations. The processing language is based on the semantic model, so processing specifications are also invariant to these decisions. This allows a designer to specify the processing and semantics of small parts of a database (local views), and then to integrate these views into a global model of the database. We present operations to manipulate the model and processing specifications during the integration process. An algorithm, using these operations is given to perform the integration process.

In the past several years much attention has been given to the problem of data translation. The focus has been mainly on methodologies and specification languages for accomplishing this task. Recently, several prototype systems have emerged, and now the issues of implementation and performance must be addressed. In general, a data restructuring specification may contain multiple source and target files. This specification can be viewed as a “process graph” which is a network of restructuring operations subject to precedence constraints. One technique used to achieve good performance is that of pipelining data in the process graph. In this paper we address a number of issues pertinent to a pipelining architecture. Specifically, we give algorithms for resolving deadlock situations which can arise, and partitioning the process graph to achieve an optimal schedule for executing the restructuring steps. In addition, we discuss how pipelining has influenced the design of the restructuring operations and the file structures used in an actual system.

EXPRESS is an experimental prototype data translation system which can access a wide variety of data and restructure it for new uses. The system is driven by two very high level nonprocedural languages: DEFINE for data description and CONVERT for data restructuring. Program generation and cooperating process techniques are used to achieve efficient operation. This paper describes the design and implementation of EXPRESS. DEFINE and CONVERT are summarized and the implementation architecture presented. The DEFINE description is compiled into a customized PL/1 program for accessing source data. The restructuring specified in CONVERT is compiled into a set of customized PL/1 procedures to derive multiple target files from multiple input files. Job steps and job control statements are generated automatically. During execution, the generated procedures run under control of a process supervisor, which coordinates buffer management and handles file allocation, deallocation, and all input/output requests. The architecture of EXPRESS allows efficiency in execution by avoiding unnecessary secondary storage references while at the same time allowing the individual procedures to be independent of each other. Its modular structure permits the system to be extended or transferred to another environment easily.

This paper describes in detail a translation definition language, CONVERT, for specifying the mapping of the instances of source items, which may be components of one or more files, into instances of target data, which may constitute multiple files.The language is designed for the class of users who are familiar with the logical aspects of their data, know what they want to be done, but do not want to be concerned with the details of how to accomplish it. It is high level and non-procedural according to current standards.The language provides very powerful and highly flexible restructuring capability. Although primarily designed for hierarchically structured data, it is applicable to other kinds of data structures as well. It is believed that the language can handle all common processes required in a data translation. Furthermore, the simple underlying concepts enable the users to visualize the translation processes, thus making data conversion a much simpler task. Examples to illustrate the languages' applications are included.