A framework for caching relevant data items for checking integrity constraints of mobile database

In a mobile environment, due to the various constraints inherited from limitations of wireless communication and mobile devices, checking for integrity constraints to maintain the consistent state of mobile databases is an important issue that needs to be addressed. Hence, in this paper we propose a framework for caching relevant data items needed during the process of checking integrity constraints of mobile databases. This is achieved by analyzing the relationships among the integrity tests (simplified form of integrity constraints) to be evaluated for a given update operation. This improves the checking mechanism by preventing delays during the process of checking constraints and performing the update. Hence, our model speeds up the checking process

Cloud transactions and caching for improved performance in clouds and DTNs

In distributed transactional systems deployed over some massively decentralized cloud servers, access policies are typically replicated. Interdependencies ad inconsistencies among policies need to be addressed as they can affect performance, throughput and accuracy. Several stringent levels of policy consistency constraints and enforcement approaches to guarantee the trustworthiness of transactions on cloud servers are proposed. We define a look-up table to store policy versions and the concept of Tree-Based Consistency approach to maintain a tree structure of the servers. By integrating look-up table and the consistency tree based approach, we propose an enhanced version of Two-phase validation commit (2PVC) protocol integrated with the Paxos commit protocol with reduced or almost the same performance overhead without affecting accuracy and precision. A new caching scheme has been proposed which takes into consideration Military/Defense applications of Delay-tolerant Networks (DTNs) where data that need to be cached follows a whole different priority levels. In these applications, data popularity can be defined not only based on request frequency, but also based on the importance like who created and ranked point of interests in the data, when and where it was created; higher rank data belonging to some specific location may be more important though frequency of those may not be higher than more popular lower priority data. Thus, our caching scheme is designed by taking different requirements into consideration for DTN networks for defense applications. The performance evaluation shows that our caching scheme reduces the overall access latency, cache miss and usage of cache memory when compared to using caching schemes --Abstract, page iv

Dependable IPTV Hosting

This research focuses on the challenges of hosting 3rd party RESTful applications that have to meet specific dependability standards. To provide a proof of concept I have implemented an architecture and framework for the use case of internet protocol television. Delivering TV services via internet protocols over high-speed connections is commonly referred to as IPTV (internet protocol television). Similar to the app-stores of smartphones, IPTV platforms enable the emergence of IPTV services in which 3rd party developers provide services to consumer that add value to the IPTV experience. A key issue in the IPTV ecosystem is that currently telecommunications IPTV providers do not have a system that allows 3rd party developers to create applications that meet their standards. The main challenges are that the 3rd party applications must be dependable, scalable and adhere to service level agreements. This research provides an architecture and framework to overcome these challenges

Mobile web resource tracking during a disaster or crisis situation

This paper proposes a prototype solution for a mobile web resource tracking system using mobile devices during an emergency situation. The system provides real time data to a decision maker so that he/she can effectively and efficiently monitor resources and assess the situation accordingly. Mobile devices (i.e., smart phones) support the ease of use for any location and at anytime. The Internet technology is selected to enable multiple or cross platform technology solutions for different mobile devices. Resources in the scope of this project are human resources (e.g., a doctor, a police officer) and a chemical list in a room. With the use of a GPS-enabled device or a wireless-enabled device, the system is used to provide the current location of the human resources. Transferring data between system databases and mobile devices is one of the important areas to address in this project. Since location data of a user is sensitive data, data should be protected via an encrypted protected network. In addition, because of the urgency of any crisis situation, it is critical that data from the system be able to be retrieved in a reasonable time frame. The investigation includes the exploration of database and data transfer solutions to meet the data availability during emergency conditions on mobile devices. This document includes a description of the system design, a review of current technologies, proposed methodology, and the implementation. Review of the literature section provides background information on current available technologies that were studied (section 3). Four identified factors are suggested in the system design – usability, security, availability, and performance. The discussion of which technology is selected for each feature can be found in the implementation section 4. Proposed future research areas can be found in the conclusion section and recommendations for future work section

Incremental Consistency Guarantees for Replicated Objects

Programming with replicated objects is difficult. Developers must face the fundamental trade-off between consistency and performance head on, while struggling with the complexity of distributed storage stacks. We introduce Correctables, a novel abstraction that hides most of this complexity, allowing developers to focus on the task of balancing consistency and performance. To aid developers with this task, Correctables provide incremental consistency guarantees, which capture successive refinements on the result of an ongoing operation on a replicated object. In short, applications receive both a preliminary---fast, possibly inconsistent---result, as well as a final---consistent---result that arrives later. We show how to leverage incremental consistency guarantees by speculating on preliminary values, trading throughput and bandwidth for improved latency. We experiment with two popular storage systems (Cassandra and ZooKeeper) and three applications: a Twissandra-based microblogging service, an ad serving system, and a ticket selling system. Our evaluation on the Amazon EC2 platform with YCSB workloads A, B, and C shows that we can reduce the latency of strongly consistent operations by up to 40% (from 100ms to 60ms) at little cost (10% bandwidth increase, 6% throughput drop) in the ad system. Even if the preliminary result is frequently inconsistent (25% of accesses), incremental consistency incurs a bandwidth overhead of only 27%.Comment: 16 total pages, 12 figures. OSDI'16 (to appear

Object-Relational Mapping as a Persistence Mechanism for Object-Oriented Applications

Many object-oriented applications created today, especially Web applications, use relational databases for persistence. Often there is a straightforward correspondence between database tables on the one hand and application classes on the other. Application developers usually write a great deal of code to connect to and query the database, code which differs little from class to class and is often tedious to write. Moreover, the parallel class and table structures constitute a duplication of information, which requires duplication of work and increases the likelihood of errors. Ideally, we could automate this duplication, rendering it invisible to developers. This is the idea behind object-relational mapping (ORM), which achieves the mapping between the object-oriented world and the relational world automatically. Many existing ORM tools do not realize the goal of fully transparent persistence, however, and ORM tools have not become pervasive in the software industry. We survey ORM technology, probing issues of ORM system architecture and examining real-world ORM systems. We consider the state of the art in ORM, asking why it is not more popular than it is and anticipating the future course of ORM system development

A Systematic Literature Review on Progressive Web Application Practice and Challenges

This research aims to establish a knowledge of Progressive Web Application (PWA) method practices based on published empirical investigation, the problems that the PWA method may face, and the PWA method's approach to experimental studies. We also looked for PWA practices that might address the issues with the prior method. We performed a broad, automated search to find SLRs and 43 papers published from 1 January 2015 to 6 November 2021 that discuss PWA. Specific inclusion and exclusion criteria were applied to determine which relevant studies we used for our research purposes. The review identified 31 practices of PWA, Six challenges of the previous approach of mobile application development that get resolved by PWA, and seven challenges posed by the practice of PWA. PWA was introduced in 2015, and since 2017 the studies on PWA topics have started increasing. The distribution of studies based on nations is spread evenly. 74\% of selected studies are about the practice of the PWA. Although it cannot be generalized that the PWA approach handles the challenge of the previous method, some studies reported that PWA covers the problems of the previous methods. However, despite its benefits, PWA still has some challenges, mostly related to browser support