> im curious about application variables under the j2ee web application
> are these used frequently in the context of application servers, like
> resin, or are they regarded as taboo?
> also, has anyone heard of the shared nothing architecture? how does
> that pertain, if at all, to the j2ee paradigm?
> i was discussing application variables w/ some members of php-general
> and from the sound of it; they are taboo in the php world.
Application variables are not possible in the php world when using the C
implementation. Each php request is served by a different proccess, and
those processes cannot share data without using an intermediary like a
database, the file system, or a cache server.
The processes also cannot share database connections, so connection
pooling is not an option, which can be a serious scalability issue.
Using the application scope for things like common configuration and
caching can be very effective. The "cache-coherence problem" is a
problem if the application requires that the cache have absolutely up to
date information in it. Much of the information served on the web can
be cached and have some inconsistency for a short period of time.
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