Adoption and enthusiasm on distributed caching has gained momentum with growing popularity of the social networking and blogging sites as part of the "Web 2.0" revolution.Before getting into the details let us take a quick look into what is caching and why distributed caching is important.
Wikipedia defines cache as follows:
a cache is a temporary storage area where frequently accessed data can be stored for rapid access.
Cache is a temporary storage from where data can be accessed much faster than permanent or persisted storage.In today's distributed web applications we have a web server,application server and a database (generally a RDBMS).Retrieving data from the database server generally involves network and disk I/O thus reducing response time.For faster access we store/cache a copy of the frequently accessed data in Web server's memory.Today's web applications are mostly deployed in a clustered environment (server farms) for meeting the availability and scalability requirements.As the application is running on multiple servers we need to have the in-memory cache distributed as well.
