I am experiencing an odd behavior of my spring boot websocket set-up. Sometimes it works, sometimes it doesn't, it just feels random. I have tried the several setups, none proved solid: I moved the last piece of code in a commandlinerunner inside the primary class of the application and the last choice was a different class with @Component annotation.
My setup is the following: I use a jdbc driver (pgjdbc-ng) to use the listen notify function of postgres.I have a function and a trigger that listens to a specific postgres table for inserations. If any occur, notifications are sent through the websocket. The other and is an angular app that uses ng2-stompjs to listen to /topic/notificari for notifications. I am not posting the code because the notifications don't get out of spring, the angular is not the problem.
Kind regards,
This is my WebSocketConfiguration
Override
public void configureMessageBroker(MessageBrokerRegistry registry) {
registry.enableSimpleBroker("/topic", "/queue", "/user", "/notificari");
registry.setApplicationDestinationPrefixes("/app");
registry.setUserDestinationPrefix("/user");
}
@Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint("/socket").setAllowedOrigins("*")
.setHandshakeHandler(new CustomHandshakeHandler());
}
I am using a class ListenNotify and the JDBC driver pgjdbc-ng to connect to the postgresql db and use listen notify functionality
public class ListenNotify {
private BlockingQueue queue = new ArrayBlockingQueue(20);
PGConnection connection;
public ListenNotify() {
PGNotificationListener listener = new PGNotificationListener() {
@Override
public void notification(int processId, String channelName, String payload) {
queue.add(payload);
}
};
try {
PGDataSource dataSource = new PGDataSource();
dataSource.setHost("localhost");
dataSource.setDatabase("db");
dataSource.setPort(5432);
dataSource.setUser("user");
dataSource.setPassword("pass");
connection = (PGConnection) dataSource.getConnection();
connection.addNotificationListener(listener);
Statement statement = connection.createStatement();
statement.execute("LISTEN n_event");
statement.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
public BlockingQueue getQueue() {
return queue;
}
}
And finally this is the code that instantiate the ListenNotify object and listens to postgres for events that might trigger notifications that have to be send using websocket.
@Component
public class InstantaNotificari {
@Autowired
SimpMessagingTemplate template;
@EventListener(ApplicationReadyEvent.class)
public void runn() {
System.out.println("invocare met");
ListenNotify ln = new ListenNotify();
BlockingQueue queue = ln.getQueue();
System.out.println("the que ies "+ queue);
while (true) {
try {
String msg = (String) queue.take();
System.out.println("msg " + msg);
template.convertAndSend("/topic/notificari", msg);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
