最近几年来，地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持，如城市管理、区划、环境整治等等，地理信息成为信息时代重要的组成部分之一； “数字地球”概念的提出，更进一步推动了作为其技术支撑的GIS的发展。 与此同时，一些学者致力于相关的理论研究，如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面，并且这两个方面构成了相互促进的发展过程。
Memcached is a free open source, high-performance, distributed in-memory object caching system.
Memcached is a software developed by Brad Fitzpatric of Danga Interactive, asubsidiary of LiveJournal. Now it has become an important factor to improvethe scalability of Web applications in many services, such as mixi, hatena,Facebook, Vox, LiveJournal and so on.
Memcached is a memory-based key-value storage, which is used to store arbitrary data (strings, objects) of small pieces. This data can be the result of database calls, API calls, or page rendering.
Memcached is simple and powerful. Its concise design facilitates rapid development, reduces the difficulty of development, and solves many problemsof large amount of data cache. Its API is compatible with most popular development languages.
In essence, it is a concise key-value storage system.
The purpose of general use is to reduce the number of database visits by caching database query results, so as to improve the speed and scalability of dynamic Web applications.
Memcached official website: https://memcached.org/ . The protocol is simple Based on Built-in memory storage Many languages have implemented connections Perl PHP Python Ruby C# C / C + Lua Wait LiveJournal Wikipedia Flickr Bebo Twitter Typepad Yellowbot Youtube WordPress.com Craigslist Mixi 1.1.1. Features ¶
memcached as a high-speed distributed cache server, it has the followingcharacteristics. libevent event handling based on memcached distributed that do not communicate with each other 1.1.2. Supported languages ¶
memcached the client side is mainly Perl and PHP. only memcached listed on the website are: 1.1.3. Memcached user ¶