I have a service called payment-service which is down, and this is called inside a zeebe handler.Since the service is down it should call fallbackmethod of hystrix. But it is returning me success.
main class
controller class
delegate class
when I am executing localhost:8081/order-process it shows me success.
and in the console I get the error as
I/O error on GET request for "http://localhost:8080/payment-service": Connection refused:
Please let me know why this fallback method is not getting called.
The reason your REST service returns "success" is that you successfully started your job worker (https://docs.zeebe.io/basics/job-workers.html). The job worker then executing the jobs/service tasks from your BPMN processes.
Hystrix will be used WITHIN the handler to do the call, so a potential exception or default value needs to be taken into account WITHIN the handle method.
Is Spring Controller obeys the synchronized process by adding keyword in the method?
When tried to provide synchronize it seems method not blocked and two threads are executing the same method at same time. Checked with Thread.sleep(50000)
Have used #Scope("request")
You'll need to add appropriate synchronization around critical sections in your code.
I am calling a REST service and the provider has supplied a client. Client's specification is to use Jersey 2.18. So i have used the below jersey dependencies
Jersey-client-2.18.jar
Jersey-common-2.18.jar
Jersey-entity-filtering-2.18.jar
Jersey-guava-2.18.jar
jersey-media-json-jackson-2.18.jar
I am making calls using scheduledThreadPoolExecutor and my application is running in tc server and JDK 1.8. Sporadically i get the below exception. I tried searching this exception in google but no luck. But i see the below for almost everytime
Cannot create new registration for component type class > org.glassfish.jersey.client.authentication.HttpAuthenticationFeature
Exception
java.lang.NullPointerException at
org.glassfish.jersey.model.internal.CommonConfig.configureFeatures(CommonConfig.java:694)
at
org.glassfish.jersey.model.internal.CommonConfig.configureMetaProviders(CommonConfig.java:644)
at
org.glassfish.jersey.client.ClientConfig$State.configureMetaProviders(ClientConfig.java:365)
at
org.glassfish.jersey.client.ClientConfig$State.initRuntime(ClientConfig.java:398)
at
org.glassfish.jersey.client.ClientConfig$State.access$000(ClientConfig.java:88)
at
org.glassfish.jersey.client.ClientConfig$State$3.get(ClientConfig.java:120)
at
org.glassfish.jersey.client.ClientConfig$State$3.get(ClientConfig.java:117)
at
org.glassfish.jersey.internal.util.collection.Values$LazyValueImpl.get(Values.java:340)
at
org.glassfish.jersey.client.ClientConfig.getRuntime(ClientConfig.java:726)
at
org.glassfish.jersey.client.ClientRequest.getConfiguration(ClientRequest.java:285)
at
org.glassfish.jersey.client.JerseyInvocation.validateHttpMethodAndEntity(JerseyInvocation.java:126)
at
org.glassfish.jersey.client.JerseyInvocation.(JerseyInvocation.java:98)
at
org.glassfish.jersey.client.JerseyInvocation.(JerseyInvocation.java:91)
at
org.glassfish.jersey.client.JerseyInvocation$Builder.method(JerseyInvocation.java:411)
at
org.glassfish.jersey.client.JerseyInvocation$Builder.get(JerseyInvocation.java:307)
I resolved this issue. My implementation was wrong. The client object was defined as a class level variable and it was initialized during every method call. During parallel call. every thread concurrent call attacks the same class level object and tries to modify and hence the object was not properly initialized. Now i fixed it by injecting the class from spring so that it is not modified during every call.
I'm using the annotation based approach of spring amqp in a multithreaded environment (i have multiple consumers => multiple rabbit listener containers).
#RabbitListener(queues = "tasks")
public void receiveMessage(#Payload Task task) {
// usage of httpClient here with its own httpContext (would be fine)
// this method gets called from different listenerContainers / threads
}
My component which contains the annotated receiveMessage() method needs to do some http calls with the apache http client. Since i'm working with multiple consumers at the same time, this method gets called from different threads and the apache http client documentation says that i should create a httpContext for each thread to be thread safe. Since all threads are calling the same component method i can't put the httpContext into the component.
Is there something like a listener container context for each listener container where i can put the httpClientContext? Or does somebody have an idea how to solve this easy? I thought about ThreadLocal or a central registry for httpContexts but it would be fine if this would be more easy.
There is nothing like that provided by the framework; the simplest solution is to store them in something like a LinkedBlockingQueue and check one out, use it, and put it back in the queue when you're done (creating one as necessary if the queue is empty).
ThreadLocal will work too, but I prefer to use a pool.
I am new to spring and want to implement long polling for a website to display admin message immediately when it becomes available to all clients,i searched google for hours and could only find out deferredresult(spring 3.2) can be used to implement it.my question is how i can achieve long polling with deferredresult, I would appreciate it if anyone could refer me to such a tutorial.
Another option is to use AsyncContext. This will keep the initial GET request "open" and enable you to send multiple messages as part of the response, unlike DeferredResult which allows to send only ONE response message. Here is a good-link that explains how !
Straight from the horses mouth.
You have two basic options: Option 1 is a Callable
, where the Callable returns the String view name (you may also be able to use #ResponseBody or some of the other normal Spring return types like ModelAndView, but I have never investigated that).
Option two is to return DeferredResult, which is like Callable. except you can pass that off to a separate thread and fill in the results there. Again, not sure if you can return a ModelAndView or use #ResponseBody to return XML/JSON, but I am sure you can.
Short background about DeferredResult:
Your controller is eventually a function executed by the servlet container (for that matter, let's assume that the server container is Tomcat) worker thread. Your service flow start with Tomcat and ends with Tomcat. Tomcat gets the request from the client, holds the connection, and eventually returns a response to the client. Your code (controller or servlet) is somewhere in the middle.
Consider this flow:
Tomcat get client request.
Tomcat executes your controller.
Release Tomcat thread but keep the client connection (don't return response) and run heavy processing on different thread.
When your heavy processing complete, update Tomcat with its response and return it to the client (by Tomcat).
Because the servlet (your code) and the servlet container (Tomcat) are different entities, then to allow this flow (releasing tomcat thread but keep the client connection) we need to have this support in their contract, the package javax.servlet, which introduced in Servlet 3.0 . Spring MVC use this new Servlet 3.0 capability when the return value of the controller is DeferredResult or Callable, although they are two different things. Callable is an interface that is part of java.util, and it is an improvement for the Runnable interface. DeferredResult is a class designed by Spring to allow more options (that I will describe) for asynchronous request processing in Spring MVC, and this class just holds the result (as implied by its name) while your Callable implementation holds the async code. So it means you can use both in your controller, run your async code with Callable and set the result in DeferredResult, which will be the controller return value. So what do you get by using DeferredResult as the return value instead of Callable? DeferredResult has built-in callbacks like onError, onTimeout, and onCompletion. It makes error handling very easy. In addition, as it is just the result container, you can choose any thread (or thread pool) to run on your async code. With Callable, you don't have this choice.
Here you can find a simple working examples I created with both options, Callable and DeferredResult.