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From Xiaochen Chen <xiaochenchen....@gmail.com>
Subject Re: NPE when a resource tries to use @Context injected ContextResolver
Date Sat, 20 Jul 2013 22:01:26 GMT
Couldn't agree more! That totally makes sense.

Though I'm surprised this hasn't been fixed …

Thanks Jordan. I'll test it out. And confirm later.

On Jul 20, 2013, at 5:26 PM, Jordan Zimmerman <jordan@jordanzimmerman.com> wrote:

> BTW - how many thousands of man years have been lost to erasure?!! What a horrible mistake
that decision was.
> 
> -JZ
> 
> On Jul 20, 2013, at 2:24 PM, Jordan Zimmerman <jordan@jordanzimmerman.com> wrote:
> 
>> OK - I have a workaround. You need to create a wrapper class that acts as the context
resolver:
>> 
>> @Provider
>> public class MyResolver implements ContextResolver<DiscoveryContext<ServicePayload>>
>> {
>>     private final GenericDiscoveryContext<ServicePayload> context;
>> 
>>     public MyResolver(GenericDiscoveryContext<ServicePayload> context)
>>     {
>>         this.context = context;
>>     }
>> 
>>     @Override
>>     public DiscoveryContext<ServicePayload> getContext(Class<?> type)
>>     {
>>         return context;
>>     }
>> }
>> 
>> In the Singletons, instead of adding discoveryContext, add:
>> 
>> 	new MyResolver(discoveryContext)
>> 
>> In my tests, this fixed the problem.
>> 
>> -Jordan
>> 
>> On Jul 19, 2013, at 5:01 PM, xiaochen.chen@barclays.com wrote:
>> 
>>> Hello,
>>>  
>>> I am using Curator’s curator-x-discovery-sever and trying to set it up with
Jersey and Tomcat.
>>>  
>>> I created my resource class, injected the class. Also injected those singletons
mentioned.
>>> (following this page http://curator.incubator.apache.org/curator-x-discovery-server/index.html
)
>>>  
>>> However, I am getting NPE when the contextResolver tries to getContext.
>>>  
>>> The ContextResolver singleton is injected, and it looks like the @Context injection
isn’t happening.
>>>  
>>> Can someone please help me to see what is wrong with my code?
>>>  
>>> Thanks.
>>>  
>>> Here is my code, the highlighted line is where the exception happens:
>>>  
>>> Resource
>>>  
>>> @Path("compass")
>>> public class CompassResource extends DiscoveryResource<ServicePayload>
>>> {
>>>     public CompassResource(@Context ContextResolver<DiscoveryContext<ServicePayload>>
resolver)
>>>     {
>>>         super(resolver.getContext(DiscoveryContext.class));
>>>     }
>>> }
>>>  
>>> Application
>>>  
>>> public class DiscoveryServerApplication extends Application
>>> {
>>>     @Override
>>>     public Set<Class<?>> getClasses() {
>>>         Set<Class<?>> s = new HashSet<Class<?>>();
>>>         //s.add(MyResource.class);
>>>         s.add(CompassResource.class);
>>>         return s;
>>>     }
>>>  
>>>     @Override
>>>     public Set<Object> getSingletons() {
>>>         final Set<Object> singletons = Sets.newHashSet();
>>>  
>>>         // inject ServiceDiscovery singleton
>>>         CuratorFrameworkFactory.Builder builder = CuratorFrameworkFactory.builder()
>>>                 .connectString("localhost:2181").sessionTimeoutMs(300000).connectionTimeoutMs(30000)
>>>                 .retryPolicy(new ExponentialBackoffRetry(1000,3));
>>>         CuratorFramework client = builder.build();
>>>         client.start();
>>>  
>>>         ServiceDiscovery<ServicePayload> serviceDiscovery = ServiceDiscoveryBuilder.builder(ServicePayload.class)
>>>                 .client(client).basePath("/").build();
>>>         singletons.add(serviceDiscovery);
>>>  
>>>         // inject DiscoveryContext singleton
>>>         GenericDiscoveryContext<ServicePayload> discoveryContext = new
GenericDiscoveryContext<ServicePayload>
>>>                 (serviceDiscovery, new RandomStrategy<ServicePayload>(),
500, ServicePayload.class);
>>>         singletons.add(discoveryContext);
>>>  
>>>         // inject JsonServiceInstanceMarshaller singleton
>>>         singletons.add(new JsonServiceInstanceMarshaller(discoveryContext));
>>>  
>>>         // inject JsonServiceInstancesMarshaller singleton
>>>         singletons.add(new JsonServiceInstancesMarshaller(discoveryContext));
>>>  
>>>         // inject JsonServiceNamesMarshaller
>>>         singletons.add(new JsonServiceNamesMarshaller());
>>>  
>>>         return singletons;
>>>     }
>>> }
>>> web.xml
>>>  
>>>     <servlet>
>>>         <servlet-name>Curator Discovery Server</servlet-name>
>>>         <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
>>>         <init-param>
>>>             <param-name>javax.ws.rs.Application</param-name>
>>>             <param-value>com.lb.eqr.discovery.server.DiscoveryServerApplication</param-value>
>>>         </init-param>
>>>         <load-on-startup>1</load-on-startup>
>>>     </servlet>
>>>     <servlet-mapping>
>>>         <servlet-name>Curator Discovery Server</servlet-name>
>>>         <url-pattern>/*</url-pattern>
>>>     </servlet-mapping>
>>>  
>>> ===========
>>>  
>>> Here is the exception:
>>>  
>>> root cause
>>> java.lang.NullPointerException
>>>         com.lb.eqr.discovery.server.CompassResource.<init>(CompassResource.java:23)
>>>         sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
>>>         sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
>>>         sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
>>>         java.lang.reflect.Constructor.newInstance(Constructor.java:513)
>>>         org.glassfish.hk2.utilities.reflection.ReflectionHelper.makeMe(ReflectionHelper.java:1091)
>>>         org.jvnet.hk2.internal.ClazzCreator.createMe(ClazzCreator.java:244)
>>>         org.jvnet.hk2.internal.ClazzCreator.create(ClazzCreator.java:319)
>>>         org.jvnet.hk2.internal.SystemDescriptor.create(SystemDescriptor.java:448)
>>>         org.glassfish.jersey.process.internal.RequestScope.findOrCreate(RequestScope.java:157)
>>>         org.jvnet.hk2.internal.Utilities.createService(Utilities.java:2203)
>>>         org.jvnet.hk2.internal.ServiceLocatorImpl.getService(ServiceLocatorImpl.java:579)
>>>         org.jvnet.hk2.internal.ServiceLocatorImpl.getService(ServiceLocatorImpl.java:566)
>>>         org.glassfish.jersey.internal.inject.Injections.getOrCreate(Injections.java:172)
>>>         org.glassfish.jersey.server.model.MethodHandler$ClassBasedMethodHandler.getInstance(MethodHandler.java:185)
>>>         org.glassfish.jersey.server.internal.routing.PushMethodHandlerRouter.apply(PushMethodHandlerRouter.java:105)
>>>         org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:118)
>>>         org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:121)
>>>         org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:121)
>>>         org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:121)
>>>         org.glassfish.jersey.server.internal.routing.RoutingStage._apply(RoutingStage.java:121)
>>>         org.glassfish.jersey.server.internal.routing.RoutingStage.apply(RoutingStage.java:102)
>>>         org.glassfish.jersey.server.internal.routing.RoutingStage.apply(RoutingStage.java:62)
>>>         org.glassfish.jersey.process.internal.Stages.process(Stages.java:197)
>>>         org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:215)
>>>         org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
>>>         org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
>>>         org.glassfish.jersey.internal.Errors.process(Errors.java:315)
>>>         org.glassfish.jersey.internal.Errors.process(Errors.java:297)
>>>         org.glassfish.jersey.internal.Errors.process(Errors.java:267)
>>>         org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
>>>         org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:198)
>>>         org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:946)
>>>         org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:323)
>>>         org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:372)
>>>         org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:335)
>>>         org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:218)
>>>  
>>>  
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>>> 
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>>> 
>> 
> 


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