A Methodology for Engineering Collaborative and ad-hoc Mobile Applications using SyD Middleware

Today’s web applications are more collaborative and utilize standard and ubiquitous Internet protocols. We have earlier developed System on Mobile Devices (SyD) middleware to rapidly develop and deploy collaborative applications over heterogeneous and possibly mobile devices hosting web objects. In this paper, we present the software engineering methodology for developing SyD-enabled web applications and illustrate it through a case study on two representative applications: (i) a calendar of meeting application, which is a collaborative application and (ii) a travel application which is an ad-hoc collaborative application. SyD-enabled web objects allow us to create a collaborative application rapidly with limited coding effort. In this case study, the modular software architecture allowed us to hide the inherent heterogeneity among devices, data stores, and networks by presenting a uniform and persistent object view of mobile objects interacting through XML/SOAP requests and responses. The performance results we obtained show that the application scales well as we increase the group size and adapts well within the constraints of mobile devices

SyD: A Middleware Testbed for Collaborative Applications over Small Heterogeneous Devices and Data Stores

Abstract. Currently, it is possible to develop a collaborative application running on a collection of heterogeneous, possibly mobile, devices, each potentially hosting data stores, using existing middleware technologies such as JXTA, BREW, compact.NET and J2ME. However, they require too many ad-hoc techniques as well as cumbersome and time-consuming programming. Our System on Mobile Devices (SyD) middleware, on the other hand, has a modular architecture that makes such application de-velopment very systematic and streamlined. The architecture supports transactions over mobile data stores, with a range of remote group invo-cation options and embedded interdependencies among such data store objects. The architecture further provides a persistent uniform object view, group transaction with Quality of Service (QoS) speci¯cations, and XML vocabulary for inter-device communication. This paper presents the basic SyD concepts, introduces the architecture and the design of the SyD middleware and its components. We also provide guidelines fo

Abstract

We study the coverage problem from the fault tolerance point of view for sensor networks. Fault tolerance is a critical issue for sensors deployed in places where they are not easily replaceable, repairable and rechargeable. The failure of one node should not incapacitate the entire network. We propose three 1-fault tolerant models, and we compare them to each other, as well as with the minimal coverage model [11]. To study the reliability of proposed models, we develop the Markov model for each of them and calculate the reliability assuming a constant failure rate. We show that the most unreliable model among these three models is the hexagonal model, and the improved model is the most reliable on long term. For short time from the start, the square model is more reliable, but after a short while, the improved model becomes and remains the better one

An XML Based Access Control Architecture for Pervasive Computing

There is a huge prevalence of mobile devices being connected to the Internet because of high demands for information access and dissemination. It is now well understood that XML plays a vital role as a means for information representation, exchange, and storage. Naturally, XML data is exchanged and stored as these mobile devices communicate with each other, and over the web. A major concern for one device requesting data (objects, services or raw data) from another device is security. Access control policies are important models that control access to data for authorized devices. In an XML setting, access control policies are necessary to control access to parts of XML documents. It becomes challenging in pervasive computing environment as the devices have small memory foot print, disconnection, low battery powers, etc. In this paper, we propose an XML based access control along with cryptography for secure transmission of XML data in pervasive environments