Multi-tier Web Applications Research Articles

Queueing-Model-Based Adaptive Control of Multi-Tiered Web Applications

Web applications have been increasingly deployed on the Internet. How to effectively allocate system resources to meet the Service Level Objectives (SLOs) is a challenging problem for Web application providers. In this article, we propose a scheme for automated performance control of Web applications via dynamic resource allocations. The scheme uses a queueing model predictor and an online adaptive feedback loop that enforces admission control of the incoming requests to ensure the desired response time target is met. The proposed Queueing-Model-Based Adaptive Control approach combines both the modeling power of queueing theory and the self-tuning power of adaptive control. Therefore, it can handle both modeling inaccuracies and load disturbances in a better way. To evaluate the proposed approach, we built a multi-tiered Web application testbed with open-source components widely adopted in industry. Experimental studies conducted on the testbed demonstrated the effectiveness of the proposed scheme.

The CMS dataset bookkeeping service

The CMS Dataset Bookkeeping Service (DBS) has been developed to catalog all CMS event data from Monte Carlo and Detector sources. It provides the ability to identify MC or trigger source, track data provenance, construct datasets for analysis, and discover interesting data. CMS requires processing and analysis activities at various service levels and the DBS system provides support for localized processing or private analysis, as well as global access for CMS users at large. Catalog entries can be moved among the various service levels with a simple set of migration tools, thus forming a loose federation of databases. DBS is available to CMS users via a Python API, Command Line, and a Discovery web page interfaces. The system is built as a multi-tier web application with Java servlets running under Tomcat, with connections via JDBC to Oracle or MySQL database backends. Clients connect to the service through HTTP or HTTPS with authentication provided by GRID certificates and authorization through VOMS. DBS is an integral part of the overall CMS Data Management and Workflow Management systems.

Virtualization-based autonomic resource management for multi-tier Web applications in shared data center

As large data centers emerge, which host multiple Web applications, it is critical to isolate different application environments for security reasons and to provision shared resources effectively and efficiently to meet different service quality targets at minimum operational cost. To address this problem, we developed a novel architecture of resource management framework for multi-tier applications based on virtualization mechanisms. Key techniques presented in this paper include (1) establishment of the analytic performance model which employs probabilistic analysis and overload management to deal with non-equilibrium states; (2) a general formulation of the resource management problem which can be solved by incorporating both deterministic and stochastic optimizing algorithms; (3) deployment of virtual servers to partition resource at a much finer level; and (4) investigation of the impact of the failure rate to examine the effect of application isolation. Simulation experiments comparing three resource allocation schemes demonstrate the advantage of our dynamic approach in providing differentiated service qualities, preserving QoS levels in failure scenarios and also improving the overall performance while reducing the resource usage cost.

Customizing Visualization in Three-Dimensional Urban GIS via Web-Based Interaction

This paper presents our research results of visualizing three-dimensional 3D city models in a web explorer environment under the supports of the digital building model, the digital terrain model, large-scale true urban orthoimage, and actual building sidewall pictures. A system has been designed and developed under a client/server architecture, which integrates the Internet Geographic Infor- mation System with multitier web applications for creation of a 3D city model. The front-end client provides a user interface for setting the properties of the 3D city model, and the back-end server processes these parameters and generates a 3D model, which is then sent back to the Virtual Reality Modeling Language-enabled World Wide Web browser for display and navigation. The technology for display and navigation of the 3D model is implemented using Java Server Pages/Servlet technology built under multitier web architecture. The technology for data accessing and processing is implemented through Java programming language. The displayer is linked to the database, where the required GIS spatial data are stored. The results from our experiments demonstrated that this developed system is able to display and visualize 3D city data in a web environment for public accesses. Using the sidewall pictures taken from real city buildings, we refill the white walls of urban buildings into a real appearance as seen in our real world cities. The player provides several click buttons to enhance the effect and position of visualization, including rotation, zoom, pan, seek, etc. The users can easily view the details of a specified building or/and the entire city in a moving 3D manner, and locate a specific building.