Enforcing Interdependencies and Executing Transactions Atomically over Autonomous Mobile Data Stores Using SyD Link Technology

System of Mobile Devices (SyD) is a middleware we developed that can be used for implementing collaborative, mobile, and distributed applications over heterogeneous devices, data stores, and computing environments. Current prototype implementation of SyD consists of five modules. These modules provide ease of programming in the areas of distributed communication, remote method invocation, service publication and discovery, directory services, distributed service invocation and aggregation, event handling, collaborative link creation and enforcement. A central module is SyDLink, which allows SyD-based applications to create "coordination" links. Coordination links represent dependencies among heterogeneous devices and application components. Based on the underlying eventand -trigger mechanism, they allow automatic updates as well as real-time enforcement of global constraints and interdependencies. SyDLink objects provide the underlying mechanism in SyD to enforce atomic execution of distributed transactions. We explain and demonstrate the use of SyDLink objects via a running example, a collaborative SyD calendar application, throughout the paper

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

Coordinating Heterogeneous Web Services through Handhelds using SyD’s Wrapper Framework

Tying web services together to build large, distributed, collaborative applications has gathered noticeable momentum and a lot of research is being put in it. Along with composition of the web services, coordination is one key aspect that has been considered keenly. Many frameworks, languages and protocols have been proposed for web service composition and coordination. With the advancement in wireless technology and rapid deployment of mobile services, collaborative application development for small devices using such composed web services finds a new research area. Much less work has been done in the area of web service coordination for mobile environment. In this thesis, we propose a new distributed approach in service composition and coordination and show that our approach works well in an environment containing mobile heterogeneous devices. We discuss a novel approach of SyD (System on Devices)wrapper framework for dynamically creating and executing web bonds among various heterogeneous web services. The wrapper is a lightweight SyD application object that encapsulates composition and coordination logic and provides higher level of coordination among bonded entities. The wrapper framework gives small devices full capability to run distributed collaborative applications that use heterogeneous web services. We have also developed and analyzed experiments to showcase the performance of SyD Wrapper Framework

Global Semantic Integrity Constraint Checking for a System of Databases

In today’s emerging information systems, it is natural to have data distributed across multiple sites. We define a System of Databases (SyDb) as a collection of autonomous and heterogeneous databases. R-SyDb (System of Relational Databases) is a restricted form of SyDb, referring to a collection of relational databases, which are independent. Similarly, X-SyDb (System of XML Databases) refers to a collection of XML databases. Global integrity constraints ensure integrity and consistency of data spanning multiple databases. In this dissertation, we present (i) Constraint Checker, a general framework of a mobile agent based approach for checking global constraints on R-SyDb, and (ii) XConstraint Checker, a general framework for checking global XML constraints on X-SyDb. Furthermore, we formalize multiple efficient algorithms for varying semantic integrity constraints involving both arithmetic and aggregate predicates. The algorithms take as input an update statement, list of all global semantic integrity constraints with arithmetic predicates or aggregate predicates and outputs sub-constraints to be executed on remote sites. The algorithms are efficient since (i) constraint check is carried out at compile time, i.e. before executing update statement; hence we save time and resources by avoiding rollbacks, and (ii) the implementation exploits parallelism. We have also implemented a prototype of systems and algorithms for both R-SyDb and X-SyDb. We also present performance evaluations of the system

Distributed Web Service Coordination for Collaboration Applications and Biological Workflows

In this dissertation work, we have investigated the main research thrust of decentralized coordination of workflows over web services. To address distributed workflow coordination, first we have developed “Web Coordination Bonds” as a capable set of dependency modeling primitives that enable each web service to manage its own dependencies. Web bond primitives are as powerful as extended Petri nets and have sufficient modeling and expressive capabilities to model workflow dependencies. We have designed and prototyped our “Web Service Coordination Management Middleware” (WSCMM) system that enhances current web services infrastructure to accommodate web bond enabled web services. Finally, based on core concepts of web coordination bonds and WSCMM, we have developed the “BondFlow” system that allows easy configuration distributed coordination of workflows. The footprint of the BonFlow runtime is 24KB and the additional third party software packages, SOAP client and XML parser, account for 115KB