Tuesday, March 25, 2008
A reverse proxy or surrogate is a proxy server that is installed within the neighborhood of one or more servers. Typically, reverse proxies are used in front of Web servers. All connections coming from the Internet addressed to one of the Web servers are routed through the proxy server, which may either deal with the request itself or pass the request wholly or partially to the main web servers.
A reverse proxy dispatches in-bound network traffic to a set of servers, presenting a single interface to the caller. For example, a reverse proxy could be used for load balancing a cluster of web servers. In contrast, a forward proxy acts as a proxy for out-bound traffic. For example, an ISP may use a proxy to forward HTTP traffic from its clients to external web servers on the internet; it may also cache the results to improve performance.
Tuesday, March 18, 2008
MySQL (pronounced /maɪˌɛskjuːˈɛl/ "my S-Q-L") is a multithreaded, multi-user SQL database management system (DBMS) which has more than 11 million installations. The basic program runs as a server providing multi-user access to a number of databases.
Originally financed in a similar fashion to the JBoss model, MySQL was owned and sponsored by a single for-profit firm, the Swedish company MySQL AB, now a subsidiary of Sun Microsystems, which holds the copyright to most of the codebase. The project's source code is available under terms of the GNU General Public License, as well as under a variety of proprietary agreements.
Monday, March 10, 2008
Computational chemistry is a branch of chemistry that uses computers to assist in solving chemical problems. It uses the results of theoretical chemistry, incorporated into efficient computer programs, to calculate the structures and properties of molecules and solids. While its results normally complement the information obtained by chemical experiments, it can in some cases predict hitherto unobserved chemical phenomena. It is widely used in the design of new drugs and materials.
Examples of such properties are structure (i.e. the expected positions of the constituent atoms), absolute and relative (interaction) energies, electronic charge distributions, dipoles and higher multipole moments, vibrational frequencies, reactivity or other spectroscopic quantities, and cross sections for collision with other particles.
Wednesday, March 05, 2008
Aviation encompasses all the activities relating to airborne devices created by human ingenuity, generally known as aircraft. These activities include the organizations and regulatory bodies as well as the personnel related with the operation of aircraft and the industries involved in airplane manufacture, development, and design.