java - How exactly are the root context and the dispatcher servlet context into a Spring MVC web application? -

i studying spring mvc , have doubt related

so, have configuration class configure dispatcherservlet handle user requests:

public class mywebappinitializer implements webapplicationinitializer {      @override     public void onstartup(servletcontext container) {          // create 'root' spring application context         annotationconfigwebapplicationcontext rootcontext = ...         // create dispatcher servlet's spring application context         annotationconfigwebapplicationcontext dispatchercontext = new annotationconfigwebapplicationcontext();         dispatchercontext.register(dispatcherconfig.class);         // register , map dispatcher servlet        servletregistration.dynamic dispatcher = container.addservlet("main", new dispatcherservlet(dispatchercontext));        dispatcher.setloadonstartup(1);        dispatcher.addmapping("main/");    } } 

it pretty clear me how dispatcherservlet works. doubts related context concept.

1) represent context? think set of beans have specific pourpose , works togheter environment. absolutly not true assertion.

2) difference between root context , dispatcher servlet context?

3) have understand beans defined in dispatchercontext have access beans defined in rootcontext (but opposite not true). why?

tnx

root context

the root-context in spring application applicationcontext loaded contextloaderlistener. context should have globally available resources services, repositories, infrastructure beans (datasource, entitymanagerfactorys etc.) etc.

the contextloaderlistener registers context in servletcontext under name org.springframework.web.context.webapplicationcontext.root.

if load applicationcontext , register name above in servletcontext qualify root-context.

child context

the child-context in spring application applicationcontext loaded dispatcherservlet (or instance messagedispatcherservlet in spring-ws application). context should contain beans relevant context, spring mvc viewresolvers, handlermappings etc.

the servlet registers context in servletcontext under name org.springframework.web.servlet.frameworkservlet.context.<servlet-name>.

root <-child relation

only child contexts have access parent context, because have multiple child contexts. instance in spring mvc combined spring ws application. parent-context detect childs finding in servletcontext known name.

if root context have access child 1 use wire beans? next if case surprising results when aop involved. aop defined in child context influence beans configured in root context.