Praveen Madiraju

Semantic Integrity Constraint Checking for Multiple XML Databases

Global semantic integrity constraints ensure integrity and consistency of data spanning multiple databases. In this paper, we take initial steps towards representing global semantic integrity constraints for XML databases. We also provide a general framework for checking global semantic integrity constraints for XML databases. Furthermore, we set forth an efficient algorithm for checking global semantic integrity constraints across multiple XML databases. Our algorithm is efficient for three reasons: (1) the algorithm does not require the update statement to be executed before the constraint check is carried out; hence, we avoid any potential problems associated with rollbacks, (2) sub constraint checks are executed in parallel, and (3) most of the processing of algorithm could happen at compile time; hence, we save time spent at run-time. As a proof of concept, we present a prototype of the system implementing the ideas discussed in this paper.

A framework for global constraint checking involving aggregates in multidatabases using granular computing

We have earlier introduced constraint checker, a general framework for checking global constraints using an agent based approach. In this paper, we complement the constraint checker with algorithms for checking global constraints involving aggregates in the presence of updates. The algorithms take as input an update statement, a list of global constraints involving aggregates, and granulizes each global constraint into sub constraint granules. The sub constraint granules are executed locally on remote sites and then the algorithm decides if a constraint is violated based on these sub constraint executions. The algorithms are efficient as the global constraint checks are

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.

A Context Aware Interruption Management System for Mobile Devices

To prevent unwanted interruptions from cell phones, this paper proposes a system solution considering user’s unavailability. We first look at desirable characteristics of the system, then design a system architecture which takes as input user preferences, relevant context information and then produces as output if an incoming call should be allowed to ring. We also present a case study application that benefit by using the interruption management system. Finally, we discuss evaluations of the system by (i) evaluating the prototype and (ii) undertaking cognitive walkthroughs of the application.

A context-aware cost of interruption model for mobile devices

Unwanted and untimely interruptions have been a major cause in the loss of productivity in recent years as they are mostly detrimental to the immediate task at hand. Multiple approaches have been proposed to address the problem of interruption by calculating cost of interruption. The cost of interruption (COI) gives as a measure the probabilistic value of harmfulness of an inopportune interruption. Bayesian Inference stands atop among the models that have been applied to calculate this COI. However Bayesian inference based models suffer from not being able to model context accurately in situations where priori, conditional probabilities and uncertainties exist while utilizing context information. Hence, this paper introduces Dempster-Shafer Theory of Evidence to model COI. Along the way, we also identify different contexts necessary for interruption management applications. We also show an illustrative example of a mobile interruption management application where the Dempster-Shafer theory is used to get a better measurement of whether to interrupt or not.

Mobile intelligent interruptions management (MIIM): a context aware unavailability system

Mobile phones that currently cause interruptions by blindly allowing calls to ring at busy moments and inappropriate situations can be managed using context aware computing, ubiquitous computing, and the available sensors built into a modern handheld. This paper proposes the architecture of a system named Mobile Intelligent Interruptions Management (MIIM), created for the automated administration of personal unavailability with regard to cell phones. Here, we provide the description of the problem, desirable characteristics and architecture of such an interruption management system. The system is being simulated and the initial results show that MIIMs computational volumes are low enough for a mobile device. Platform support has been found in Google Android.

3-L Model: A Model for Checking the Integrity Constraints of Mobile Databases

In this paper we propose a model for checking integrity constraints of mobile databases called Three-Level (3-L) model, wherein the process of constraint checking to maintain the consistent state of mobile databases is realized at three different levels. Sufficient and complete tests proposed in the previous works together with the idea of caching relevant data items for checking the integrity constraints are adopted. This has improved the checking mechanism by preventing delays during the process of checking constraints and performing the update. Also, the 3-L model reduces the amount of data accessed given that much of the tasks are performed at the mobile host, and hence speeds up the checking process.

A System Implementation of Interruption Management for Mobile Devices

As the number of worldwide cellular subscriptions approaches the worlds population, the negative effects of cell phone disruption have become increasingly apparent. With advances in mobile phones, specifically their sensor technology, mobile phones are now capable of moderating interruptions based on whether or not the user would want an interruption. Research into the area of interruption management has provided models and architectures for the creation of such an application. However, to our knowledge, there are no interruption management systems currently available in the Android or iPhone app stores that utilize a probabilistic model to moderate cell phone interruptions. A probabilistic model would be an improvement over current binary decision models as the user would not need to predetermine every possible outcome. In this project, we have used a probabilistic model to implement an interruption management system for Android OS 4.0 which utilizes five contexts: schedule, time of day, location, caller relationship, and driving. Our system intercepts the call, calculates the probability of interruption, and then changes the phones audio profile to vibrate, silent, or ring based on our model. Our performance evaluations indicate minor application foot print size, reasonable battery consumption, and very little time overhead for the application.

A methodology for engineering collaborative and ad-hoc mobile applications using SyD middleware

Todays 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.

Constraint optimization for a system of relational databases

Constraint optimization in distributed databases is an important issue as it can reduce the amount of time needed to check for the violation of global constraints when updates are performed. In this paper we address techniques to achieve optimization of constraint checking process in distributed databases. We propose architecture for optimizing constraint checking process. This architecture exploits techniques of parallelism, compile time constraint checking, localized constraint checking and history of constraint violations. We also design an algorithm which acts as a backbone to the architecture. This algorithm achieves efficiency in terms of time. Further, as a proof of concept we implement the architecture and algorithm using a mobile agent based approach. Our performance evaluations indicate a significant savings in response times and number of sites checked because of constraint optimization.