Using Spring Data Stream, How can I start reading from a queue and stop reading on demand?
I want to so something like this:
#EnableBinding(Sink.class)
public class SomeConsumer {
#StreamListener(target = Sink.INPUT)
public void receiveMsg(Message<String> message)
{
logger.info(" received new message [" + message.toString() + "] ");
}
public static void startReceiving()
{
//How to implement this logic?
}
public static void stopReceiving()
{
//How to implement this logic?
}
}
It can't be done in a static method; autowire the BindingsEndpoint and use the changeState() method.
See my answer to this question.
Related
I have a number of microservices, each running in its own container in a load balanced environment. I have a need for each instance of these microservices to create a rabbitmq queue when it starts up and delete it when it stops. I have currently defined the following property in my application properties file:
config_queue: config_${PID}
My message queue listener looks like this:
public class ConfigListener {
Logger logger = LoggerFactory.getLogger(ConfigListener.class);
// https://www.programcreek.com/java-api-examples/index.php?api=org.springframework.amqp.rabbit.annotation.RabbitListener
#RabbitListener(bindings = #QueueBinding(
value = #Queue(value = "${config_queue}",
autoDelete = "true"),
exchange = #Exchange(value = AppConstants.TOPIC_CONFIGURATION,
type= ExchangeTypes.FANOUT)
))
public void configChanged(String message){
... application logic
}
}
All this works great when I run the microservice. A queue with prefix config and process id gets created and is auto deleted when I stop the service.
However, when I run this service and others in their individual docker containers, all services have the same PID and that is 1.
Does anybody have any idea how I can create specify a queue that is unique to that instance.
Thanks in advance for your help.
Use an AnonymousQueue instead:
#SpringBootApplication
public class So72030217Application {
public static void main(String[] args) {
SpringApplication.run(So72030217Application.class, args);
}
#RabbitListener(queues = "#{configQueue.name}")
public void listen(String in) {
System.out.println(in);
}
}
#Configuration
class Config {
#Bean
FanoutExchange fanout() {
return new FanoutExchange("config");
}
#Bean
Queue configQueue() {
return new AnonymousQueue(new Base64UrlNamingStrategy("config_"));
}
#Bean
Binding binding() {
return BindingBuilder.bind(configQueue()).to(fanout());
}
}
AnonymousQueues are auto-delete and use a Base64 encoded UUID in the name.
I am looking for an example of a Spring Integration 4.3.14 TCP server that responds to a message using the Java DSL not XML.
The 4.3.14 requirment is set by corporate policy which also avoids XML.
The end requirment is to receive a formated text payload form a PLC and respond with likewise. The PLC code is legacy and not at all well defined and simular payloads can have diferent formats.
The easy way to deal with the input payload is to treat it as a string and deal with it in Java code.
I have a basic recive working but cant work out how to send the reply, read a lot of examples and such but now think the mind is just confued so a simple working example would be ideal.
Many thanks
Here you go...
#SpringBootApplication
public class So50412811Application {
public static void main(String[] args) {
SpringApplication.run(So50412811Application.class, args).close();
}
#Bean
public TcpNetServerConnectionFactory cf() {
return new TcpNetServerConnectionFactory(1234);
}
#Bean
public TcpInboundGateway gateway() {
TcpInboundGateway gw = new TcpInboundGateway();
gw.setConnectionFactory(cf());
return gw;
}
#Bean
public IntegrationFlow flow() {
return IntegrationFlows.from(gateway())
.transform(Transformers.objectToString())
.<String, String>transform(String::toUpperCase)
.get();
}
// client
#Bean
public ApplicationRunner runner() {
return args -> {
Socket socket = SocketFactory.getDefault().createSocket("localhost", 1234);
socket.getOutputStream().write("foo\r\n".getBytes()); // default CRLF deserializer
InputStream is = socket.getInputStream();
int in = 0;
while (in != 0x0a) {
in = is.read();
System.out.print((char) in);
}
socket.close();
};
}
}
Thanks for reading ahead of time. In my main method I have a PublishSubscribeChannel
#Bean(name = "feeSchedule")
public SubscribableChannel getMessageChannel() {
return new PublishSubscribeChannel();
}
In a service that does a long running process it creates a fee schedule that I inject the channel into
#Service
public class FeeScheduleCompareServiceImpl implements FeeScheduleCompareService {
#Autowired
MessageChannel outChannel;
public List<FeeScheduleUpdate> compareFeeSchedules(String oldStudyId) {
List<FeeScheduleUpdate> sortedResultList = longMethod(oldStudyId);
outChannel.send(MessageBuilder.withPayload(sortedResultList).build());
return sortedResultList;
}
}
Now this is the part I'm struggling with. I want to use completable future and get the payload of the event in the future A in another spring bean. I need future A to return the payload from the message. I think want to create a ServiceActivator to be the message end point but like I said, I need it to return the payload for future A.
#org.springframework.stereotype.Service
public class SFCCCompareServiceImpl implements SFCCCompareService {
#Autowired
private SubscribableChannel outChannel;
#Override
public List<SFCCCompareDTO> compareSFCC(String state, int service){
ArrayList<SFCCCompareDTO> returnList = new ArrayList<SFCCCompareDTO>();
CompletableFuture<List<FeeScheduleUpdate>> fa = CompletableFuture.supplyAsync( () ->
{ //block A WHAT GOES HERE?!?!
outChannel.subscribe()
}
);
CompletableFuture<List<StateFeeCodeClassification>> fb = CompletableFuture.supplyAsync( () ->
{
return this.stateFeeCodeClassificationRepository.findAll();
}
);
CompletableFuture<List<SFCCCompareDTO>> fc = fa.thenCombine(fb,(a,b) ->{
//block C
//get in this block when both A & B are complete
Object theList = b.stream().forEach(new Consumer<StateFeeCodeClassification>() {
#Override
public void accept(StateFeeCodeClassification stateFeeCodeClassification) {
a.stream().forEach(new Consumer<FeeScheduleUpdate>() {
#Override
public void accept(FeeScheduleUpdate feeScheduleUpdate) {
returnList new SFCCCompareDTO();
}
});
}
}).collect(Collectors.toList());
return theList;
});
fc.join();
return returnList;
}
}
Was thinking there would be a service activator like:
#MessageEndpoint
public class UpdatesHandler implements MessageHandler{
#ServiceActivator(requiresReply = "true")
public List<FeeScheduleUpdate> getUpdates(Message m){
return (List<FeeScheduleUpdate>) m.getPayload();
}
}
Your question isn't clear, but I'll try to help you with some info.
Spring Integration doesn't provide CompletableFuture support, but it does provide an async handling and replies.
See Asynchronous Gateway for more information. And also see Asynchronous Service Activator.
outChannel.subscribe() should come with the MessageHandler callback, by the way.
I am trying to create a event based system for communicating between services using Apache Kafka as Messaging system and Spring Cloud Stream Kafka.
I have written my Receiver class methods as below,
#StreamListener(target = Sink.INPUT, condition = "headers['eventType']=='EmployeeCreatedEvent'")
public void handleEmployeeCreatedEvent(#Payload String payload) {
logger.info("Received EmployeeCreatedEvent: " + payload);
}
This method is specifically to catch for messages or events related to EmployeeCreatedEvent.
#StreamListener(target = Sink.INPUT, condition = "headers['eventType']=='EmployeeTransferredEvent'")
public void handleEmployeeTransferredEvent(#Payload String payload) {
logger.info("Received EmployeeTransferredEvent: " + payload);
}
This method is specifically to catch for messages or events related to EmployeeTransferredEvent.
#StreamListener(target = Sink.INPUT)
public void handleDefaultEvent(#Payload String payload) {
logger.info("Received payload: " + payload);
}
This is the default method.
When I run the application, I am not able to see the methods annoated with condition attribute being called. I only see the handleDefaultEvent method being called.
I am sending a message to this Receiver Application from the Sending/Source App using the below CustomMessageSource class as below,
#Component
#EnableBinding(Source.class)
public class CustomMessageSource {
#Autowired
private Source source;
public void sendMessage(String payload,String eventType) {
Message<String> myMessage = MessageBuilder.withPayload(payload)
.setHeader("eventType", eventType)
.build();
source.output().send(myMessage);
}
}
I am calling the method from my controller in Source App as below,
customMessageSource.sendMessage("Hello","EmployeeCreatedEvent");
The customMessageSource instance is autowired as below,
#Autowired
CustomMessageSource customMessageSource;
Basicaly, I would like to filter messages received by the Sink/Receiver application and handle them accordingly.
For this I have used the #StreamListener annotation with condition attribute to simulate the behaviour of handling different events.
I am using Spring Cloud Stream Chelsea.SR2 version.
Can someone help me in resolving this issue.
It seems like the headers are not propagated. Make sure you include the custom headers in spring.cloud.stream.kafka.binder.headers http://docs.spring.io/autorepo/docs/spring-cloud-stream-docs/Chelsea.SR2/reference/htmlsingle/#_kafka_binder_properties .
Is it possible to create rooms with STOMP and Spring 4? Socket.IO has rooms built in, so I'm wondering if Spring has this
My code at the moment:
#MessageMapping("/room/greet/{room}")
#SendTo("/room/{room}")
public Greeting greet(#DestinationVariable String room, HelloMessage message) throws Exception {
return new Greeting("Hello, " + room + "!");
}
It would be ideal to have #SendTo("/room/{room}")
however, I am limited to:
#SendTo("/room/room1")
#SendTo("/room/room2")
#SendTo("/room/room3")
etc...which is VERY VERY unideal
The client is:
stompClient.subscribe('/room/' + roomID, function(greeting){
showGreeting(JSON.parse(greeting.body).content);
});
where roomID can be room1, room2, or room3...
What If I want more rooms? It feels like such a pain right now
It looks like this "room" feature is actually a publish/subscribe mechanism, something achieved with topics in Spring Websocket support (see STOMP protocol support and destinations for more info on this).
With this example:
#Controller
public class GreetingController {
#MessageMapping("/room/greeting/{room}")
public Greeting greet(#DestinationVariable String room, HelloMessage message) throws Exception {
return new Greeting("Hello, " + message.getName() + "!");
}
}
If a message is sent to "/room/greeting/room1", then the return value Greeting will be automatically sent to "/topic/room/greeting/room1", so the initial destination prefixed with "/topic".
If you wish to customize the destination, you can use #SendTo just like you did, or use a MessagingTemplate like this:
#Controller
public class GreetingController {
private SimpMessagingTemplate template;
#Autowired
public GreetingController(SimpMessagingTemplate template) {
this.template = template;
}
#MessageMapping("/room/greeting/{room}")
public void greet(#DestinationVariable String room, HelloMessage message) throws Exception {
Greeting greeting = new Greeting("Hello, " + message.getName() + "!");
this.template.convertAndSend("/topic/room/"+room, greeting);
}
}
I think taking a quick look at the reference documentation and some useful examples, such as a portfolio app and a chat app should be useful.
You can use netty socket the implementation of socket io in java