J2EE application for clustered servers : focus on balancing workloads among clustered servers : a thesis presented in partial fulfilment of the requirements for the degree of Master of Information Science in Computer Science at Massey University, Albany, New Zealand

J2EE has become a de facto platform for developing enterprise applications not only by its standard based methodology but also by reducing the cost and complexity of developing multi-tier enterprise applications. J2EE based application servers keep business logic separate from the front-end applications (client-side) and back-end database servers. The standardized components and containers simplify J2EE application design. The containers automatically manage the fundamental system level services for its components, which enable the components design to focus on the business requirement and business logic. This study applies the latest J2EE technologies to configure an online benchmark enterprise application - MG Project. The application focuses on three types of components design including Servlet, entity bean and session bean. Servlets run on the web server Tomcat, EJB components, session beans and entity beans run on the application server JBoss and the database runs on the database server Postgre SQL. This benchmark application is used for testing the performance of clustered JBoss due to various load-balancing policies applied at the EJB level. This research also focuses on studying the various load-balancing policies effect on the performance of clustered JBoss. As well as the four built-in load-balancing policies i.e. First Available, First Available Identical All Proxies, Random Robin and Round Robin, the study also extend the JBoss Load balance Policy interface to design two dynamic load-balancing policies. They are dynamic and dynamic weight-based load-balancing policies. The purpose of dynamic load-balancing policies design is to ensure minimal response time and obtain better performance by dispatching incoming requests to the appropriate server. However, a more accurate policy usually means more communications and calculations, which give an extra burden to a heavily loaded application server that can lead to drops in the performance

The Sobolev Inequalities on Real Hyperbolic Spaces and Eigenvalue Bounds for Schr\"odinger Operators with Complex Potentials

In this paper, we prove the uniform estimates for the resolvent $(\Delta - \alpha)^{-1}$ as a map from $L^q$ to $L^{q'}$ on real hyperbolic space $\mathbb{H}^n$ where $\alpha \in \mathbb{C}\setminus [(n - 1)^2/4, \infty)$ and $2n/(n + 2) \leq q < 2$. In contrast with analogous results on Euclidean space $\mathbb{R}^n$, the exponent $q$ here can be arbitrarily close to $2$. This striking improvement is due to two non-Euclidean features of hyperbolic space: the Kunze-Stein phenomenon and the exponential decay of the spectral measure. In addition, we apply this result to the study of eigenvalue bounds of the Schr\"{o}dinger operator with a complex potential. The improved Sobolev inequality results in a better long range eigenvalue bound on $\mathbb{H}^n$ than that on $\mathbb{R}^n$.Comment: A revised version. In particular, a gap in the proof of Proposition 11 in the previous version is fixe

Pure Entertainment or Social Harmony? Understanding Private Returns to Social Spending on Household Ceremonies in China

Recent social spending inflation in China has led to its growth rate far exceeding that of income and other consumption. In this paper, we estimate private returns to social spending, such as higher social status and larger social network that serve as certain functions. In almost all specifications we find that gift spending has significant private returns, but the returns are biased towards richer households. Upon comparing different measures of centrality, we also find that social connections are more accurately characterized when weighted by their intensities (values), capturing their role in mobilizing scarce resource in the network. Furthermore, social status and network may change long-term income trajectory and the resulted consumption. However, our findings do not suggest that they are vehicles through which they could facilitate smoother consumption against shocks. The result does not depend on how heterogeneous the shocks are.social network, social status, private return, social spending, consumption, Consumer/Household Economics,

Increasing Returns to Scale in U.S. manufacturing industries: evidence from direct and reverse regression.

In this paper, I compare the OLS and IV estimators for the direct and reverse regression models in the context of estimating returns to scale and technical progress. It shows that the direct and reverse OLS estimators are inconsistent, that the direct OLS is always more precise than the reverse OLS under the normality assumption, and that the direct IV estimator and its reverse counterpart are consistent and asymptotically equivalent. Working with data from U.S. manufacturing industries over the last half-century, the estimation results show that in most industries increasing returns to scale are important and technical progress is small when it comes to explaining productivity growth.