contextConfigLocation init parameters in web.xml

Question

I have a problem with understanding what actually is going on in my project with app context. I have created new part of project which use spring-mvc

there are RestConfig class

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "restService.com.websystique.springmvc.*")
public class RestConfig {
}

RestServlet class

@WebServlet(name = "PSC Rest Servlet", urlPatterns = "/rest/*", loadOnStartup = 1)

    public class RestServlet extends DispatcherServlet {
        public RestServlet() {
            super(new GenericWebApplicationContext());
        }
    }

as you can see those classes are servlet and its config.

all work correctly

below web.xml whole my project

<?xml ...>
    ...another code
    <context-param>
        <param-name>contextClass</param-name>
        <param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
    </context-param>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            com.psc.config.JpaConfig, com.psc.config.ServicesConfig, restService.com.websystique.springmvc.configuration.RestConfig
        </param-value>
    </context-param>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>


...another code
</web-app>

I would like to know how my RestConfig context recognises servlet RestServlet (because everything works correctly). I've specified RestConfig in context-param, well than its file will be part of root context.

<context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            com.psc.config.JpaConfig, com.psc.config.ServicesConfig, restService.com.websystique.springmvc.configuration.RestConfig
        </param-value>
    </context-param>

But where is RestServlet context? If RestConfig is RestServlet context, why it is part of root context? Can servlet context be a part of root context? If yes, my controllers, services and etc will created two times?

If I specify servlet in web.xml, and not include RestConfig in init-param(context-param) for whole app, I will make good thing or it won't make any changes?

this is part of log in console

11:27:01.183 [localhost-startStop-1] INFO  o.s.web.context.ContextLoader - Root WebApplicationContext: initialization started
11:27:01.369 [localhost-startStop-1] INFO  o.s.w.c.s.AnnotationConfigWebApplicationContext - Refreshing Root WebApplicationContext: startup date [Thu Aug 11 11:27:01 MSK 2016]; root of context hierarchy
11:27:01.478 [localhost-startStop-1] INFO  o.s.w.c.s.AnnotationConfigWebApplicationContext - Successfully resolved class for [com.psc.config.JpaConfig]
11:27:01.553 [localhost-startStop-1] INFO  o.s.w.c.s.AnnotationConfigWebApplicationContext - Successfully resolved class for [com.psc.config.ServicesConfig]
11:27:01.579 [localhost-startStop-1] INFO  o.s.w.c.s.AnnotationConfigWebApplicationContext - Successfully resolved class for [restService.com.websystique.springmvc.configuration.RestConfig]
11:27:02.843 [localhost-startStop-1] INFO  o.s.b.f.a.AutowiredAnnotationBeanPostProcessor - JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
11:27:03.269 [localhost-startStop-1] INFO  o.s.o.j.LocalContainerEntityManagerFactoryBean - Building JPA container EntityManagerFactory for persistence unit 'psc'
11:27:17.430 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/branch/{id}],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.Branch>> restService.com.websystique.springmvc.controller.BranchController.getBranchesWithId(java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.432 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/branch],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.Branch>> restService.com.websystique.springmvc.controller.BranchController.getBranches(java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.434 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/region/{id}],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.Region>> restService.com.websystique.springmvc.controller.RegionController.getBranchesWithId(java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.435 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/region],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.Region>> restService.com.websystique.springmvc.controller.RegionController.getBranches(java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.436 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/region/ || /region],methods=[POST]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.Region>> restService.com.websystique.springmvc.controller.RegionController.createUser(com.psc.model.Region)
11:27:17.436 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/region/{id}],methods=[DELETE]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.Region>> restService.com.websystique.springmvc.controller.RegionController.deleteRegionById(long)
11:27:17.438 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/role/{id}],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.Role>> restService.com.websystique.springmvc.controller.RoleController.getBranchesWithId(java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.439 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/role],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.Role>> restService.com.websystique.springmvc.controller.RoleController.getBranches(java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.439 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/role/ || /role],methods=[POST]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.Role>> restService.com.websystique.springmvc.controller.RoleController.createUser(com.psc.model.Role)
11:27:17.442 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/roleTree/{id}],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.RoleTree>> restService.com.websystique.springmvc.controller.RoleTreeController.getBranchesWithId(java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.443 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/roleTree],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.RoleTree>> restService.com.websystique.springmvc.controller.RoleTreeController.getBranches(java.lang.Long,java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.443 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/roleTree/ || /roleTree],methods=[POST]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.RoleTree>> restService.com.websystique.springmvc.controller.RoleTreeController.createUser(com.psc.model.RoleTree)
11:27:17.444 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/user/{id}],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.User>> restService.com.websystique.springmvc.controller.UserController.getBranchesWithId(java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.445 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/user],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.User>> restService.com.websystique.springmvc.controller.UserController.getBranches(java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.446 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/user/ || /user],methods=[POST]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.User>> restService.com.websystique.springmvc.controller.UserController.createUser(com.psc.model.User)
11:27:17.449 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/userRole/{id}],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.UserRole>> restService.com.websystique.springmvc.controller.UserRoleController.getBranchesWithId(java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.450 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/userRole],methods=[GET]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.UserRole>> restService.com.websystique.springmvc.controller.UserRoleController.getBranches(java.lang.Long,java.lang.Long,javax.servlet.http.HttpServletRequest)
11:27:17.451 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerMapping - Mapped "{[/userRole/ || /userRole],methods=[POST]}" onto public org.springframework.http.ResponseEntity<restService.com.websystique.springmvc.model.Box<com.psc.model.UserRole>> restService.com.websystique.springmvc.controller.UserRoleController.createUser(com.psc.model.UserRole)
11:27:18.091 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.RequestMappingHandlerAdapter - Looking for @ControllerAdvice: Root WebApplicationContext: startup date [Thu Aug 11 11:27:01 MSK 2016]; root of context hierarchy
11:27:18.249 [localhost-startStop-1] INFO  o.s.w.s.m.m.a.ExceptionHandlerExceptionResolver - Detected @ExceptionHandler methods in tempControllerAdvice
11:27:18.330 [localhost-startStop-1] INFO  o.s.web.context.ContextLoader - Root WebApplicationContext: initialization completed in 17137 ms
11:27:18.419 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Installed AtmosphereHandler com.vaadin.server.communication.PushAtmosphereHandler mapped to context-path: /*
11:27:18.420 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Installed the following AtmosphereInterceptor mapped to AtmosphereHandler com.vaadin.server.communication.PushAtmosphereHandler
11:27:18.430 [localhost-startStop-1] INFO  org.atmosphere.util.IOUtils - META-INF/services/org.atmosphere.cpr.AtmosphereFramework not found in class loader
11:27:18.466 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Atmosphere is using org.atmosphere.util.VoidAnnotationProcessor for processing annotation
11:27:18.497 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Installed WebSocketProtocol org.atmosphere.websocket.protocol.SimpleHttpProtocol 
11:27:18.522 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Installing Default AtmosphereInterceptors
11:27:18.524 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework -   org.atmosphere.interceptor.CorsInterceptor : CORS Interceptor Support
11:27:18.524 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework -   org.atmosphere.interceptor.CacheHeadersInterceptor : Default Response's Headers Interceptor
11:27:18.526 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework -   org.atmosphere.interceptor.PaddingAtmosphereInterceptor : Browser Padding Interceptor Support
11:27:18.527 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework -   org.atmosphere.interceptor.AndroidAtmosphereInterceptor : Android Interceptor Support
11:27:18.527 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Dropping Interceptor org.atmosphere.interceptor.HeartbeatInterceptor
11:27:18.528 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework -   org.atmosphere.interceptor.SSEAtmosphereInterceptor : SSE Interceptor Support
11:27:18.529 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework -   org.atmosphere.interceptor.JSONPAtmosphereInterceptor : JSONP Interceptor Support
11:27:18.532 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework -   org.atmosphere.interceptor.JavaScriptProtocol : Atmosphere JavaScript Protocol
11:27:18.533 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework -   org.atmosphere.interceptor.WebSocketMessageSuspendInterceptor : org.atmosphere.interceptor.WebSocketMessageSuspendInterceptor
11:27:18.535 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework -   org.atmosphere.interceptor.OnDisconnectInterceptor : Browser disconnection detection
11:27:18.536 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework -   org.atmosphere.interceptor.IdleResourceInterceptor : org.atmosphere.interceptor.IdleResourceInterceptor
11:27:18.537 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Set org.atmosphere.cpr.AtmosphereInterceptor.disableDefaults to disable them.
11:27:18.545 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Using EndpointMapper class org.atmosphere.util.DefaultEndpointMapper
11:27:18.545 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Using BroadcasterCache: org.atmosphere.cache.UUIDBroadcasterCache
11:27:18.546 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Default Broadcaster Class: org.atmosphere.cpr.DefaultBroadcaster
11:27:18.547 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Broadcaster Polling Wait Time 100
11:27:18.547 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Shared ExecutorService supported: true
11:27:18.548 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Messaging Thread Pool Size: Unlimited
11:27:18.548 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Async I/O Thread Pool Size: 200
11:27:18.548 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Using BroadcasterFactory: org.atmosphere.cpr.DefaultBroadcasterFactory
11:27:18.548 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Using WebSocketProcessor: org.atmosphere.websocket.DefaultWebSocketProcessor
11:27:18.549 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Invoke AtmosphereInterceptor on WebSocket message true
11:27:18.549 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - HttpSession supported: true
11:27:18.549 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Atmosphere is using DefaultAtmosphereObjectFactory for dependency injection and object creation
11:27:18.550 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Atmosphere is using async support: org.atmosphere.container.Tomcat7Servlet30SupportWithWebSocket running under container: Apache Tomcat/7.0.47 using javax.servlet/3.0
11:27:18.550 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Atmosphere Framework 2.2.7.vaadin1 started.
11:27:18.555 [localhost-startStop-1] INFO  o.atmosphere.cpr.AtmosphereFramework - Installed AtmosphereInterceptor  Track Message Size Interceptor using | with priority BEFORE_DEFAULT 
11:27:18.579 [localhost-startStop-1] INFO  o.a.c.c.C.[.[.[/ProductCatalog] - Initializing Spring FrameworkServlet 'PSC Rest Servlet'
11:27:18.580 [localhost-startStop-1] INFO  r.c.w.springmvc.RestServlet - FrameworkServlet 'PSC Rest Servlet': initialization started
11:27:18.584 [localhost-startStop-1] INFO  o.s.w.c.s.GenericWebApplicationContext - Refreshing org.springframework.web.context.support.GenericWebApplicationContext@274638b4: startup date [Thu Aug 11 11:27:18 MSK 2016]; parent: Root WebApplicationContext
11:27:18.602 [localhost-startStop-1] INFO  r.c.w.springmvc.RestServlet - FrameworkServlet 'PSC Rest Servlet': initialization completed in 22 ms
11:27:18.631 [main] INFO  o.a.coyote.http11.Http11Protocol - Starting ProtocolHandler ["http-bio-8080"]

Answer 1

From what I understand of your code, you've specified that all beans should be retrieved through the context loader listener, which acts like a global context, from which all dispatcher servlets can retrieve beans.

Usually, a dispatcher servlet is backed by an XML context whose default file name is derived from the name you give the servlet in web.xml. If the dispatcher servlet is called dispatcher then the file name is dispatcher-servlet.xml. Since you're not declaring any specific context for PSC Rest Servlet, you're only benefitting from the top-level context.

As for the rest of your questions. There is only one definition of your beans at the moment. If you decide to split between a top-level context (application context provided by context loader listener) and o lower-level context accessible only to your dispatcher servlet, you should take care not to have 2 definitions of the same bean. One way to structure your contexts is to split them by themes and decide which are solely used by the web aspect of your app, which are for the database, which are cross-cutting concerns, like logging, monitoring or transactions... There is no single way to do it. You could have transactions, services and repositories in the application context, while things like marshallers, converters, controllers and the like stay on the dispatcher side.