Why two different serviceLocators in petstore demo 1.3 ?? 2003-10-06 - By Sean Brydon
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Hi,
We have 2 examples of service locator pattern, one with caching and the
other with no caching. The web tier uses the caching version, where as
in the opc application of petstore which is all EJBs and has no view or
web tier, it uses no caching for the service locator. It is not clear
that there is any performance benefit from this caching mechanism in
EJBs since the container closely manages objects and their
lifecycle.Since performane is the primary reason for this caching
strategy with the service locator, you might want to do some testing
before you choose a strategy to optimize for performance in your
deployment environment.
Also, this way you get examples of 2 different strategies :-)
This is explained in more detail at
http://java.sun.com/blueprints/patterns/ServiceLocator.html
hope that helps,
Sean
peng wang wrote:
>Hi,
>
>In petstore, I find there are two kinds of service
>locators, one is for the web tier, the other for the
>ejb tier.
>
>In web tier a componentManager gets locator instance
>by invoking static method:
> static public ServiceLocator getInstance() {
> return me;
> }
>Since there is only one instance, does it then form a
>bottle neck in web tier?
>
>In ejb tier, an ejbAction get locator by creating a
>new
>instance like:
> ServiceLocator sl = new ServiceLocator();
>So I think there are multi serviceLocator instances in
>
>the ejb tier(differing from web tier).
>
>What is the force for two kinds of serviceLocators in
>petstore application? When need to use the first, and
>when the second??
>
>Thanks!
>
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