N-tier Application Research Articles

A sustainable ubiquitous engagement platform for open government Implementation.

Open government is known as a systematic procedure of government towards ensuring collaboration, transparency, innovation and participation to make government answerable to its citizens. It has been identified to have four stages of implementation with a given conceptual model known as the open government implementation model (OGIM). The first stage of the model is increasing data transparency, the second stage is improving open participation, the third stage is enhancing open collaboration and the fourth and final stage is realizing ubiquitous engagement. Each stage of this model provides its own deliverables from the first stage down to the last however, this paper focuses on the specific final stage of the model which is realizing ubiquitous engagement. In order to realize ubiquitous engagement, a platform for citizen engagement needs to be made available everywhere and at any time. The paper is aimed at proposing a sustainable engagement framework for open government as well as using the adopted framework for the design of an n-tier application architecture for citizen’s engagement. The ubiquitous engagement platform is a mobile platform which provides a suitable avenue for active citizen participation in government policies and procedures. It is a one-stop application enabling government transparency and effective citizen communication. With the introduction of the platform, it bridges the communication gap between the citizens and government. Thereby enabling citizen’s participation to enabled at available at any time and at anyplace via a reliable platform. The platform also enables government transparency and trust in government.

Mitigating Tail Response Time of n-Tier Applications

Consistent low response time is essential for e-commerce due to intense competitive pressure. However, practitioners of web applications have often encountered the long-tail response time problem in cloud data centers as the system utilization reaches moderate levels (e.g., 50%). Our fine-grained measurements of an open source n-tier benchmark application (RUBBoS) show such long response times are often caused by Cross-tier Queue Overflow (CTQO). Our experiments reveal the CTQO is primarily created by the synchronous nature of RPC-style call/response inter-tier communications, which create strong inter-tier dependencies due to the request processing chain of classic n-tier applications composed of synchronous RPC/thread-based servers. We remove gradually the dependencies in n-tier applications by replacing the classic synchronous servers (e.g., Apache, Tomcat, and MySQL) with their corresponding event-driven asynchronous version (e.g., Nginx, XTomcat, and XMySQL) one-by-one. Our measurements with two application scenarios (virtual machine co-location and background monitoring interference) show that replacing a subset of asynchronous servers will shift the CTQO, without significant improvements in long-tail response time. Only when all the servers become asynchronous the CTQO is resolved. In synchronous n-tier applications, long-tail response times resulting from CTQO arise at utilization as low as 43%. On the other hand, the completely asynchronous n-tier system can disrupt CTQO and remove the long tail latency at utilization as high as 83%.

Optimizing N-Tier Application Scalability in the Cloud

An effective cloud computing environment requires both good performance and high efficiency of computing resources. Through extensive experiments using a representative n-tier benchmark application (Rice University Bulletin Board System (RUBBoS)), we show that the soft resource allocation (e.g., thread pool size and database connection pool size) in component servers has a significant impact on the overall system performance, especially at high system utilization scenarios. Concretely, the same software resource allocation can be a good setting in one hardware configuration and then becomes an either under- or over-allocation in a slightly different hardware configuration, causing a significant performance drop. We have also observed some interesting phenomena that were caused by the non-trivial dependencies between the soft resources of servers in different tiers. For instance, the thread pool size in an Apache web server can limit the total number of concurrent requests to the downstream servers, which surprisingly decreases the Central Processing Unit (CPU) utilization of the Clustered Java Database Connectivity (C-JDBC) clustering middleware as the workload increases. To provide a globally optimal (or near-optimal) soft resource allocation of each tier in the system, we propose a practical iterative solution approach by combining a soft resource aware queuing network model and the fine-grained measurement data of every component server. Our results show that to truly scale complex distributed systems such as n-tier web applications with expected performance in the cloud, we need to carefully manage soft resource allocation in the system.

Integrating Concurrency Control in n-Tier Application Scaling Management in the Cloud

Scaling complex distributed systems such as e-commerce is an importance practice to simultaneously achieve high performance and high resource efficiency in the cloud. Most previous research focuses on hardware resource scaling to handle runtime workload variation. Through extensive experiments using a representative n-tier web application benchmark (RUBBoS), we demonstrate that scaling an n-tier system by adding or removing VMs without appropriately re-allocating soft resources (e.g., server threads and connections) may lead to significant performance degradation resulting from implicit change of request processing concurrency in the system, causing either over- or under-utilization of the critical hardware resource in the system. We build a concurrency-aware model that determines a near optimal soft resource allocation of each tier by combining some operational queuing laws and the fine-grained online measurement data of the system. We then develop a dynamic concurrency management (DCM) framework that integrates the concurrency-aware model to intelligently reallocate soft resources in the system during the system scaling process. We compare DCM with Amazon EC2-AutoScale, the state-of-the-art hardware only scaling management solution using six real-world bursty workload traces. The experimental results show that DCM achieves significantly shorter tail latency and higher throughput compared to Amazon EC2-AutoScale under all the workload traces.

An Automatic Code Generator Expert System Using Proprietary Language for Wider Business Application

The proposed System is an automatic front-end Code Generator Expert System (CGES) for ensuring wider business application for the generation of GUI with a source code for Databases. Safe keeping of data for smooth transaction in business has always been a matter of concern. With the help of the proposed CGES, with economy of effort and time, a customizable database application may be produced with a simple wizard. The CGES requires a database as a pre-requisite input. Once the normalized database is featured with a diagram, the CGES shall apply techniques according to the pre-defined algorithm; the complete application with source code in various modules shall automatically produce. By selecting the CGES solutions, an N-tier application shall give rise to a product, comprising of SQL server queries, Object Oriented features and modules. The results prove on a test working principles of the system are written in MS SQL Server and on the Visual Basic.NET source code generated by CGES.

Design of Application Layer Services for Security Automation via a Web Service Approach

N-tier application design has become very common in the IT industry. Each individual layer, such as the application and data layer has its own main functionality. This design is very helpful in securing the application from unauthorized access and in protecting it from attacks to the data layer. The data layer is the core of a company's business, as all the important information of the company will be stored in the data layer and normally will be located in a secured off- line server with limited local network access. The application layer acts as the medium to exchange data between the client layer and the data layer over a network. As such, the application layer has been increasingly targeted for intrusion and attacks. This paper will introduce a method to minimize the security risks in the n-tier application design. The method introduced in this paper will mainly focus on how to secure the application layer from various attacks such as Denial of Services (DoS) attack and spoofing attacks. This is achieved through data protection such as random encryption key generation, data encryption etc. and so forth at both the client application and the application layer. 

Rapidly Alternating Bottlenecks: A Study of Two Cases in n-Tier Applications

Rapidly Alternating Bottlenecks: A Study of Two Cases in n-Tier Applications

Rapidly Alternating Bottlenecks: A Study of Two Cases in n-Tier Applications

Rapidly Alternating Bottlenecks: A Study of Two Cases in n-Tier Applications

Research and Design of the Three-tier Distributed Network Management System Based on COM / COM + and DNA

Considered on the distributed network management system's demand of high distributives, extensibility and reusability, a framework model of Three-tier distributed network management system based on COM/COM+ and DNA is proposed, which adopts software component technology and N-tier application software framework design idea. We also give the concrete design plan of each layer of this model. Finally, we discuss the internal running process of each layer in the distributed network management system's framework model.

AN IMPLEMENTATION OF METRICS EXTRACTION AND ANALYZER TOOL

Nowadays, developers use N-tier application architecture which is a flexible and reusable structure for distribution to any number of client interfaces. In this study, we have implemented metrics extraction and analyzer tool for Business Tier and Data Access Tier source codes. We used existing object-oriented metrics and complexity software metrics as proposed for Business Tier code1,3. We use a set of metrics for the Data Access Tier that has been proposed in our previous study2. The primary aim of the implementation of the metric extraction and analyzer tool is to facilitate generation of software metrics which are used as independent variables in software quality prediction models. A secondary goal is to gather and present information on the attributes of source code to assist the programmers in managing the software projects. This tool is able to generate the principal components, correlation analysis report and descriptive statistics report. These analysis reports are essential reports for the study of software measurement and software quality management.

Smart Clients versus Web Forms

To build the presentation tier of an N-tier application using the Microsoft .NET platform, a software developer must typically choose between thin-client Web forms and smart clients. Both smart clients and Web forms have their pros and cons, and for certain applications the reasons for choosing between them are trivial. For example, smart clients make sense for an application such as Microsoft Outlook, while Web forms are a better solution for an online bill payment Web site with unknown client platforms. In most cases, however, making the correct decision requires carefully comparing smart-client and Web-form technologies' application characteristics

Eclipse: A platform for integrating development tools

Modern n-tier applications are developed using components implemented in many different technologies, including HTML, Java™, JavaServer Pages™ (JSP™), Enterprise JavaBeans™, connectors, COBOL or PL/1 programs, and relational database schemas. Creating an effective integrated development environment (IDE) for use in programming these applications presents some special challenges because a large number of different tool technologies have to be tightly integrated in support of development task flows. In order to meet these challenges, the Eclipse Platform was designed to serve as the common basis for diverse IDE-based products, providing open APIs (application programming interfaces) to facilitate this integration. This paper describes the overall architecture of the Eclipse Platform and the http://www.eclipse.org open source organization and consortium created to facilitate broad industry adoption of this platform.

Server Based Java Programming

Ted Neward, Manning Publications Co, Greenwich, CT, 2000, 558 pp. ISBN: 1-88477-771-6, $49.95 Target Audience Building server based application for the future. The reader is supposed to have a good understanding of programming in Java and should also have a brief knowledge of database techniques and know the basis of communications with sockets. The author's goal is to tell the basics of application server development techniques, let you be inspired by the concepts introduced and to let you use the code that comes with the book. Another goal is to tell you how to prepare you for coming changes in technology as well. Server-Based Java Programming is a good reference book for your starting up project. Organization and Content In the forewords the author gives the background of Java and sets the language in its environment comparing it to other languages. Given this you read the book with the aim of learning on how to implement techniques and concepts presented with Java as a tool, more than from learning the Java language from scratch. Each chapter of the book is summarized in the end and the references are kept in each chapter. Neward is starting with covering Java's class loading techniques in depth and how your programs could be upgraded and extended on the fly and anywhere when using these. The following parts covering different aspects of threading are well written and not only gives a description of how Java's interface for threading works but as well tells you some idioms usable, such as active objects and polling techniques. When having these concepts Neward is moving into control and configuration issues and then into socket-based communication. The basics and background are settled and then some source code is given, as example on a simple HTTP-server. Servlets are introduced and a description how you could keep content and logic separated by using them in an n-tier application. Middleware, the chapters are covering the wide spectrum of distributed object technologies existing today such as RPC remote procedure calling, RMI remote method invocation, CORBA, RMI/IIOP and some words about message-oriented middleware as Java Messaging Service. JNI, using Java's Native Interface on the server and how you could use it is told in detail. Monitoring server application from remote application by heartbeat procedures and several simple and useful techniques notifying techniques that can be used are described in the last chapters of the book. Inconsistencies The author is also using a reference implementation GJAS to let the user understand the concepts better. This GJAS could be introduced better or would be left out I think. As with giving URL web addresses in a textbook they tend to get invalid with the time. For example the author's own website has moved. Summary The way this book is structured is excellent. The chapters come in a natural order. As the book is covering only server based programming techniques there are no page-consuming GUI pictures to be found here which makes the book compact and concise although it covers a lot. One drawback with the broad coverage of the book is that you may need some extra literature to get the job done . But if you are aware of that and need some inspiration for your startup project this is recommended. Mikael Omma Umea University

Principles and advanced techniques for better internetpresentations in obstetrics and gynecology

Internet presentations are common tools for better medical communication and better scientific work. Meanwhile a great number of gynecological and obstetrical institutions present data via the world wide web within a wide range of quality and performance. Specific HTML editors offer quick and easy presentations, but only advanced internet techniques enable interesting multimedia presentations. N-tier applications are the future standard and we must integrate them in general informatical systems. New Concepts, actual tools and general problems will be discussed and new principles similar to actual E commerce techniques are able to solve our special medical demands.