|SUMit Roster Software > Nut's Weekly > November 2000 > Cache||Nederlands · Search...|
|Sunday, 12 October 2000||September 2000 Oktober 2000 Stubborn Ticket M/F December 2000 January 2001|
The need for speed(www.useit.com/alertbox/...) remains on the internet. A lot of users are still surfing with a low speed connection.
Caching is a way of storing derived data. The original data in the database may change, while the object still contains the old values.
Here are a number of caching techniques, with increasing performance benefit and accompanying risk.
Local variableThe lightest for of caching is an object in a local variable. The object exists just as long as the method runs.
Request variableFor information between several servlets and JSP pages an instance in the request is most appropriate. The object exists until the request has finished, when the user has new output on his screen.
Session variableThis is a more heavy form, suitable for information that won't change during the session.
The object remains to exist, during the whole session, as long as the user remains on the website. This form already has some real risk of outdated information.
Object cacheThis is the most heavy form of caching. Objects remain to exist, independant of sessions. This can be done in the object layer with a static Hashmap in a Class. Multiple users can share the same object.
The object has the largest risk to get outdated.
· December 2000
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