[ http://jira.andromda.org/browse/SPRING-131?page=comments#action_12280 ]
Cyril Combe commented on SPRING-131:
------------------------------------
Here is a possible strategy for implementing stateful services with Spring
only. Feel free to comment as I am not an experienced Spring user.
Let's say that we have a stateful service <my.package.MyStatefulService>. The
applicationContext entry for this service should look like this:
<!-- MyStatefulService Service Proxy with inner MyStatefulService Service
Implementation -->
<bean id="myStatefulService"
class="org.springframework.aop.framework.ProxyFactoryBean" singleton="false">
<property name="target">
<bean class="my.package.MyStatefulServiceImpl" singleton="false">
<property name="myDao"><ref bean="myDao"/></property>
</bean>
</property>
<property name="proxyInterfaces">
<value>my.package.MyStatefulService</value>
</property>
<property name="interceptorNames">
<list>
<value>serviceTransactionInterceptor</value>
<value>hibernateInterceptor</value>
</list>
</property>
</bean>
I think that no change are required in the ServiceLocator class, but as we have
set the singleton flag to <false> for both the ProxyFactoryBean and his target,
it should return a new instance for each call.
Now the service should be cached on the client side. For instance, if dealing
with the BPM4Struts cartridge for the web layer, a dependency from a controller
to this service should produce this method in the base controller:
/**
* Returns a reference to the myStatefulService back-end service.
*/
protected final my.package.MyStatefulService
getMyStatefulService(HttpServletRequest request)
throws java.lang.Exception
{
javax.servlet.http.HttpSession session = request.getSession();
my.package.MyStatefulService service =
(my.package.MyStatefulService)session.getAttribute("myStatefulService");
if (service == null)
{
service =
my.package.ServiceLocator.instance().getMyStatefulService();
session.setAttribute("myStatefulService", service);
}
return service;
}
If the service is not referenced in the session, we ask for a new instance to
the ServiceLocator and we put it in the HttpSession object.
> Allow the creation of stateful services
> ---------------------------------------
>
> Key: SPRING-131
> URL: http://jira.andromda.org/browse/SPRING-131
> Project: Spring Cartridge
> Type: Improvement
> Reporter: Cyril Combe
> Assignee: Chad Brandon
>
> If a <<Service>> stereotyped classifier has instance scoped attributes, it
> should be implemented as a stateful service (a stateful session bean if EJBs
> are enabled).
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