I am pretty new to spring-xd and need some advice for creating a custom sink. Specifically, I would like to create a sink that registers a Websocket. The general idea is that
module upload --file "websocket-sink-0.0.1-SNAPSHOT.jar" --type "sink" --name "websocket-sink"
stream create --name "websocket-sink-test" --definition "http --port=9191 | websocket-sink --port=9292" --deploy
should install the sink module and create a stream that accepts http input on port 9191 and sends the payload to the websocket sink where clients can connect (via port 9292) and consume that data.
I pretty much followed the guidelines in the documentation and used the spring integration websocket tutorial from Josh Long's techtips (https://github.com/joshlong/techtips/tree/master/examples/spring-integration-4.1-websockets-example). So this is what i came up with
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.integration.channel.DirectChannel;
import org.springframework.integration.config.EnableIntegration;
import org.springframework.integration.dsl.IntegrationFlow;
import org.springframework.integration.dsl.IntegrationFlows;
import org.springframework.integration.dsl.support.Function;
import org.springframework.integration.websocket.ServerWebSocketContainer;
import org.springframework.integration.websocket.outbound.WebSocketOutboundMessageHandler;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.MessageHandler;
import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.web.bind.annotation.RestController;
import java.util.concurrent.Executors;
import java.util.stream.Collectors;
@Configuration
@EnableIntegration
@ComponentScan
@EnableAutoConfiguration
@RestController
public class WebsocketSink {
@Bean
ServerWebSocketContainer serverWebSocketContainer() {
return new ServerWebSocketContainer("/messages").withSockJs();
}
@Bean
MessageHandler webSocketOutboundAdapter() {
return new WebSocketOutboundMessageHandler(serverWebSocketContainer());
}
@Bean
MessageChannel input() {
return new DirectChannel();
}
@Bean
IntegrationFlow webSocketFlow() {
Function<Message, Object> splitter = m -> serverWebSocketContainer()
.getSessions()
.keySet()
.stream()
.map(s -> MessageBuilder.fromMessage(m)
.setHeader(SimpMessageHeaderAccessor.SESSION_ID_HEADER, s)
.build())
.collect(Collectors.toList());
return IntegrationFlows
.from(input())
.split(Message.class, splitter)
.channel(c -> c.executor(Executors.newCachedThreadPool()))
.handle(webSocketOutboundAdapter()).get();
}
}
some of the class level annotations (e.g. @ComponentScan or @RestController) might not be required i guess. But the thing i am missing (conceptually) is where and how websocket clients would connect to the websocket exposed by the sink (that is, how can i specify the port that should be used for the container that hosts the Websocket in the sink implementation, e.g. 9292 in the stream definition from above).
I am a little lost here so I would be grateful for any advice.
