I have a Spring Boot application that starts listening on Azure IOT Hub at application start. It is done this way:
#EventListener
public void subscribeEventMessages(ContextRefreshedEvent event) {
client
.receive(false) // set this to false to read only the newly available events
.subscribe(this::hubAllEventsCallback);
}
My problem is, that this uses ContextRefreshedEvent but in fact i only want to start it once on application start.
I also checked other methods how start something at the beginning, like CommandLineRunner.
On the other hand if implementing listeners for more standard stuff like JMS there are specific Annotations like #JmsListener or providing Beans of specific Types.
My question is: Can i leverage some of these more message(subscribe) related mechanisms to start my method?
If we don't want our #EventListener to listen on "context refresh" but only on "context start", please (try) replace:
ContextRefreshEvent
with ContextStartEvent
...which is "sibling class" with exactly this semantical difference.
I have a JAX-RS (Jersey) server with which I register and bind my stuff.
I want to print a banner when the server starts up. I want to do this using the JAX-RS framework not the web server's platform (i.e., no Jetty, Netty, Thorntail, etc hooks).
I saw the following which mentions the tried and true Servlet way of doing things:
Jax rs: How can I run a method automatically everytime my server restarts? , but that does not work because I am not running a servlet container in my server so that lifecycle call is never made.
I figured there must be a JCA-ish type object that I can register with Application/ResourceConfig that has such a lifecycle call, but I am unable to even find any kind of list of the things you can actually register.
Not to complain (but I will), but I cannot decide if this is so difficult because when they moved the project to eclipse, they broke every hyperlink to the old official documentation or that it is simply so implicit, like Spring, that it only works by github'ing other people's code and realizing, 'oh, I did not know you could do that'.
Jersey has Event Listeners. You'll want to use the ApplicationEventListener and the ApplicationEvent.Type you'll probably want to listen for to print the banner is the INITIALIZATION_FINISHED
public class MyApplicationEventListener
implements ApplicationEventListener {
#Override
public void onEvent(ApplicationEvent event) {
switch (event.getType()) {
case INITIALIZATION_FINISHED:
printBanner();
break;
}
}
#Override
public RequestEventListener onRequest(RequestEvent requestEvent) {
return null;
}
}
Using Spring Boot 2.0.0.RELEASE on Google Appengine Standard. Using autoscaling but trying to get some control about creation/destruction of the instances. Need to be able to do some cleanup and would like to log those events.
Any methods in Spring Boot like #Predestroy or ContextClosedEvent don't seem to work on GAE.
According to the documention, it should be possible to detect shutdown of an instance by adding a shutdown hook.
Documentation LifecycleManager.ShutdownHook.
Have tried to put it in several places without success.
Example as a #Bean:
#Bean
public LifecycleManager lifecycleManager() {
LifecycleManager lifecycle_manager = LifecycleManager.getInstance();
lifecycle_manager.setShutdownHook(new ShutdownHook() {
public void shutdown() {
LifecycleManager.getInstance().interruptAllRequests();
log.error("Shutdown " + getClassSimpleName() + ".");
}
});
log.warn("Created shutdown hook.");
return lifecycle_manager;
}
Shutdown hook is properly installed, but doesn't get fired when the instance goes down.
As you can read in the Google Issue Tracker:
Shutdown hooks only work for manual scaled instances on the standard runtime (...).
The shutdown hooks simply don't work on automatic and basic scaling.
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'm building a Spring application and I need to inspect my H2 in-memory database while I'm running my JUnit tests from a web browser.
In my Spring configuration I have a bean which is responsible of creating my database schema and populating it with some data which will be used within my JUnit tests. I've also added a bean in my test context which creates a web server where I eventually will look for my data.
<bean id="org.h2.tools.Server-WebServer" class="org.h2.tools.Server"
factory-method="createWebServer" init-method="start" lazy-init="false">
<constructor-arg value="-web,-webAllowOthers,-webPort,11111" />
</bean>
Everything seems ok because the database is populated properly since I can access to its data from my JUnit tests and H2 Server only runs while I'm in my test-phase (I can know that, because if I try to access to my_ip:111111 before debugging my tests I cannot connnect but I can connect afterwards once I've started my tests).
Anyway If I open my H2 console from a web browser no schema is shown in it. Any ideas??
Many thanks!!
As this is probably going to be a test-debugging feature, you can add it at runtime with your #Before:
import org.h2.tools.Server;
/* Initialization logic here */
#BeforeAll
public void initTest() throws SQLException {
Server.createWebServer("-web", "-webAllowOthers", "-webPort", "8082")
.start();
}
And then connect to http://localhost:8082/
Note: unless you need this to run as part of your CI build, you'll need to remove this code when you're finished debugging
For future reference here's another way to do it:
Start database and web servers (version can differ):
$ cd .../maven_repository/com/h2database/h2/1.4.194
$ java -cp h2-1.4.194.jar org.h2.tools.Server -tcp -web -browser
TCP server running at tcp://169.254.104.55:9092 (only local connections)
Web Console server running at http://169.254.104.55:8082 (only local connections)
Set database url for tests in code to jdbc:h2:tcp://localhost:9092/mem:mytest.
Run or debug tests.
Click Connect in browser window which opened in step 1.
Jar file for H2 can be downloaded at https://mvnrepository.com/artifact/com.h2database/h2.
Server can be started via #Before in test file like in snovelli's answer, but only in case connection to database in established afterwards, which might be a problem.
I guess the problem is that you are connecting to h2db directly from your application. Not through the server you are launching with bean. Because of this your app and h2db-web-interface can't share one in-memory database.
You should change jdbcUrl in tests to something like jdbc:h2:tcp://localhost/mem:my_DB;DB_CLOSE_DELAY=-1;MODE=Oracle and in browser you should connect to the same url.
With jdbc urls like jdbc:h2:tcp://localhost/... all connections will go through the h2db-server and you can view database state in browser.
If you have defined the jdbc url to something like jdbc:h2:mem:db in your properties, when the database is created it actually gets a bit longer name.
Add a #Autowired DataSource dataSource to your test class, set a debug point somewhere, and inspect that datasource with dataSource.getConnection() and look at the url property. In the case I'm running right this moment, it is
jdbc:h2:mem:43ed83d6-97a1-4515-a925-a8ba53cd322c
Plugging that into the web cosole shows everything I'm expecting.
It isn't the most straightforward way, but it does work.
#snovelli answer above is good.
To debug a particular test case in your IDE, add a infinite loop at the end of the test case and go to browser and launch the console and you can query the data.
Something like below
import org.h2.tools.Server;
/* Initialization logic here */
#BeforeAll
public void initTest() throws SQLException {
Server.createWebServer("-web", "-webAllowOthers", "-webPort", "8082")
.start();
}
#Test
void testMyDBOperation() {
//some db operations like save and get
while(true) {
}
}
now you can go to browser and launch the console at http://localhost:8082/
Of course delete above two changes after debugging
It is not the answer, but a debugging tip.
When you finally access h2-conole http://127.0.0.1:8082/ you may notice that database changes are not shown.
This is because the test cases are not transactional and the data is not committed. Although this behavior is good, as each test case, must run in predefined environment. It is not good if you want to debug and see database changes.
To achieve this, add #Commit annotation above test case and put a dummy line in a #AfterAll annotated method, to stop test and let you see the h2 console ( The h2 server will stop as the test finish).
#AfterAll
public static void finalizeTest() throws Exception {
System.out.print("Just put a break point here");
}
#Test
#Commit
void should_store_an_article() {
// Your test here
}