【RSocket】使用 RSocket(二)——四种通信模式实践
Source Code: https://github.com/joexu01/rsocket-demo
0. 四种通信模式
让我们来简单复习一下 RSocket 的四种通信模式:
-
即发即忘 - FireAndForget:立即发送一个请求,无需为这个请求发送响应报文。适用于监控埋点,日志上报等,这种场景下无需回执,丢失几个请求无伤大雅
-
请求响应 - RequestResponse:请求方发送一条请求消息,响应方收到请求后并返回一条响应消息。传统的HTTP是典型的Request-Response
-
流式响应 - RequestStream:请求方发送一个请求报文,响应方发回N个响应报文。传统的MQ是典型的RequestStream
-
双向通道 - Channel:创建一个通道上下文,双方可以互相发送消息。IM是个典型的RequestChannel通讯场景
1. 客户端生成和解析路由信息
*本篇文章的客户端示例文件在 rsocket-client-raw/src/main/java/org/example/FourCommunicationScheme.java
我们使用 decodeRoute
和 encodeRoute
函数来解码和编码路由信息。
static String decodeRoute(ByteBuf metadata) {
final RoutingMetadata routingMetadata = new RoutingMetadata(metadata);
return routingMetadata.iterator().next();
}
static ByteBuf encodeRoute(String route) {
return TaggingMetadataCodec.createTaggingContent(
ByteBufAllocator.DEFAULT,
Collections.singletonList(route));
}
2. RequestResponse
服务端处理函数
在这里我们编写一个简单的 Handler,它的 Route 是 test.echo
,它接收一个请求并返回请求 Payload 的 data 中的字符串。
@MessageMapping("test.echo")
public Mono<String> simplyEcho(String data) throws InterruptedException {
Thread.sleep(1500);
logger.info("[test.echo]Received echo string from client: {}", data);
return Mono.just(String.format("[test.echo]I received your string: %s. Thank you.", data));
}
注意,这里的参数也可以是 Mono<String>
,然后对 Mono 进行操作并返回。事实上,如果严格按照响应式编程的策略,这里应该直接对 Mono
进行操作。
客户端发送请求
- 生成 metadata 的 route 信息,然后将字符串和 metadata 放入 Payload
ByteBuf routeMetadata = encodeRoute("test.echo");
Payload echoPayload = ByteBufPayload.create(
ByteBufUtil.writeUtf8(ByteBufAllocator.DEFAULT, "This is a message from client using rsocket-java library."),
routeMetadata);
- 新建一个 RequestResponse,并对这次请求做一些设置;可以看到 RequestResponse 方法返回的数据类型是
Mono<Payload>
。然后我们对这个 Mono 设定一些操作(具体操作请看代码注释):
Mono<Payload> requestResponse = socket.requestResponse(echoPayload);
requestResponse
// 当 subscribe() 操作开始执行时打印一下日志
.doOnSubscribe(subscription -> logger.info("Test1 subscribed to {}", subscription.toString()))
// 当携带的请求成功后要做的事情
.doOnSuccess(payload -> {
logger.info("Test1 - Successfully returned: {}", payload.getDataUtf8());
payload.release();
})
.doOnError(throwable -> logger.info("Test1 doOnError: {}", throwable.toString()))
// 可以使用 timeout 丢弃等待超时的 Mono
//.timeout(Duration.ofSeconds(1))
// 可以使用 doOnTerminate 在请求结束后做一些工作
// .doOnTerminate(() -> {})
// 但是一定要设置 doOnError
//.doOnError(TimeoutException.class, e -> logger.info("Test1 doOnError: {}", e.toString()))
// .onErrorReturn(TimeoutException.class, DefaultPayload.create("Payload: Test1 - timeout"))
// 可以使用 log() 来观察数据的状态
//.log()
// 客户端在执行 subscribe() 操作时才会开始从服务端接收数据流
// 在响应式编程中使用 subscribe 操作符是订阅一个数据流并处理发布的数据、错误和完成信号的核心方式之一
.subscribe();
请求发出后主线程不会阻塞,所以我们需要使用 socket.onClose().block();
保持连接。
然后我们尝试运行服务端和客户端,看看一看客户端的输出:
[main] INFO org.example.RSocketClientRaw - My UUID is 0718ef3b-9ee0-42f1-9003-700a8aa9a98d
[main] INFO org.example.RSocketClientRaw - Test1 subscribed to RequestResponseRequesterMono
[reactor-tcp-epoll-2] INFO org.example.RSocketClientRaw - Test1 - Successfully returned: [test.echo]I received your string: This is a message from client using rsocket-java library.. Thank you.
服务端日志:
2023-03-12 21:47:29.291 INFO 32099 --- [or-http-epoll-2] o.example.controller.RSocketController : [connect.setup]Client connection: 0718ef3b-9ee0-42f1-9003-700a8aa9a98d
2023-03-12 21:47:32.304 INFO 32099 --- [or-http-epoll-2] o.example.controller.RSocketController : [test.echo]Received echo string from client: This is a message from client using rsocket-java library.
客户端成功地发出请求并收到来自服务端的回复。
3. FireAndForget
服务端
@MessageMapping("upload.log")
public void fireAndForgetHandler(@Headers Map<String, Object> header, RSocketRequester requester, String data) {
header.forEach((k, v) -> System.out.printf("[upload.log]header key: %s, val: %s\n", k, v));
System.out.printf("[upload.log]UploadEventLogs: Received log string from client: %s\n", data);
}
服务端接受一个请求,不返回任何结果(Fire'n'Forget),只在服务端打印 Header 的内容。
客户端
// 测试 FnF
routeMetadata = TaggingMetadataCodec.createTaggingContent(ByteBufAllocator.DEFAULT, Collections.singletonList("upload.log"));
socket.fireAndForget(
ByteBufPayload.create(
ByteBufUtil.writeUtf8(ByteBufAllocator.DEFAULT, "This is a log from client using rsocket-java library."),
routeMetadata))
.doOnSubscribe(subscription -> logger.info("Test2 - Fire And Forget onSubscribe: {}", subscription.toString()))
.subscribe();
客户端输出:
[main] INFO org.example.RSocketClientRaw - Test2 - Fire And Forget onSubscribe: FireAndForgetRequesterMono
服务端输出:
2023-03-10 15:10:25.675 INFO 5318 --- [or-http-epoll-4] o.example.controller.RSocketController : [test.echo]Received echo string from client: This is a message from client using rsocket-java library.
[upload.log]header key: dataBufferFactory, val: NettyDataBufferFactory (PooledByteBufAllocator(directByDefault: true))
[upload.log]header key: rsocketRequester, val: org.springframework.messaging.rsocket.DefaultRSocketRequester@607cc59
[upload.log]header key: lookupDestination, val: upload.log
[upload.log]header key: contentType, val: application/binary
[upload.log]header key: rsocketFrameType, val: REQUEST_FNF
[upload.log]UploadEventLogs: Received log string from client: This is a log from client using rsocket-java library.
4. RequestStream
服务端
服务端接收一个 Mono<String>
然后返回给客户端包含 10 个 String
的 Flux
。
事实上,严格按照响应式编程的策略,这里应该直接对 Mono
进行操作,可以使用 flatMapMany()
把生成的数据流通过异步方式处理,扩展出新的数据流。下面是扩展新数据流的简单示例:
Mono.just(3)
.flatMapMany(i -> Flux.range(0, i))
.subscribe(System.out::println);
在这里为了演示方便就先打印 Mono
然后新生成一个 Flux
。
@MessageMapping("handler.request.stream")
public Flux<String> responseStreaming(Mono<String> request) {
request
.doOnNext(s -> logger.info("[handler.request.stream]: {}", s))
// 可以使用 then() 结束操作链
.then()
.subscribe();
return Flux
.range(1, 10)
.map(idx -> String.format("Resp from Server: %s, Thank you!", idx));
}
客户端
请看代码注释来理解对数据流 Flux 的各种操作:
// 测试 RequestStream
routeMetadata = encodeRoute("handler.request.stream");
Flux<Payload> requestStream = socket.requestStream(
ByteBufPayload.create(
ByteBufUtil.writeUtf8(ByteBufAllocator.DEFAULT, "TEST3 - Request&Stream"),
routeMetadata));
requestStream
// 当然可以使用 map 对每个 Payload 进行操作,这会改变数据
// .map(payload -> System.out.printf("%s\n", payload.getDataUtf8()))
.doOnSubscribe(subscription -> logger.info("Test3 subscribed to {}", subscription.toString()))
// 使用 doOnNext 不会对流的数据进行改变
// doOnNext()是一个 Reactor 式流操作符,它允许编写者注册一个在每次出现新元素时执行的回调函数
.doOnNext(nextPayload -> System.out.println("Test3 Received payload: " + nextPayload.getDataUtf8()))
// 当需要从流中选择一些特定的元素时,可以使用 Flux.take(long n) 操作符
// 该操作符将创建一个新的 Flux,该 Flux 包含原始 Flux 的前 n 个元素
// take 操作符发出了指定数量的元素之后,就不再接收任何元素,并且将取消其上游发布者的订阅
// 在这里服务端使用 Flux.range 来限定 Flux 流中的元素个数
// 如果服务端使用 Flux.interval 生成一个无限长度的流,客户端使用 take 接收限定个数的元素
// 便会取消发布者的订阅
.take(5)
.subscribe();
客户端输出结果:
[main] INFO org.example.RSocketClientRaw - My UUID is 28afc749-75e1-4289-8607-14810103de6c
[main] INFO org.example.RSocketClientRaw - Test3 subscribed to RequestStreamRequesterFlux
Test3 Received payload: Resp from Server: 1, Thank you!
Test3 Received payload: Resp from Server: 2, Thank you!
Test3 Received payload: Resp from Server: 3, Thank you!
Test3 Received payload: Resp from Server: 4, Thank you!
Test3 Received payload: Resp from Server: 5, Thank you!
服务端接收到了请求:
2023-03-12 22:01:33.520 INFO 32099 --- [or-http-epoll-3] o.example.controller.RSocketController : [handler.request.stream]: TEST3 - Request&Stream
5. Channel
服务端
服务端接收来自客户端的整数字符串,将它们乘以2以后发送回去。我们不妨把处理客户端请求流的函数封装为一个 Spring Service:
@Service
public class MathService {
public Flux<String> doubleInteger(Flux<String> request) {
return request
.map(s -> {
System.out.println("received " + s);
int i = Integer.parseInt(s);
return String.valueOf(i * 2);
});
}
}
编写处理函数:
@Autowired
private MathService mathService;
@MessageMapping("handler.request.channel")
public Flux<String> responseChannel(Flux<String> payloads) {
return this.mathService.doubleInteger(payloads);
}
客户端
Flux<Payload> payloadFlux = Flux.range(-5, 10)
.delayElements(Duration.ofMillis(500))
.map(obj ->
{
ByteBuf metadata = encodeRoute("handler.request.channel");
return ByteBufPayload.create(
ByteBufUtil.writeUtf8(ByteBufAllocator.DEFAULT, obj.toString()), metadata);
});
Flux<Payload> channelResp = socket.requestChannel(payloadFlux);
channelResp
.doOnSubscribe(subscription -> logger.info("Test4 subscribed to {}", subscription.toString()))
.doOnError(throwable -> logger.info(throwable.toString()))
.doOnNext(nextPayload -> System.out.println("Test4 Received payload: " + nextPayload.getDataUtf8()))
.subscribe();
客户端输出:
[main] INFO org.example.RSocketClientRaw - My UUID is 96ff8fe7-416c-4607-9518-463114725a7a
[main] INFO org.example.RSocketClientRaw - Test4 subscribed to RequestChannelRequesterFlux
Test4 Received payload: -10
Test4 Received payload: -8
Test4 Received payload: -6
Test4 Received payload: -4
Test4 Received payload: -2
Test4 Received payload: 0
Test4 Received payload: 2
Test4 Received payload: 4
Test4 Received payload: 6
Test4 Received payload: 8
服务端输出:
2023-03-12 22:07:05.542 INFO 33083 --- [or-http-epoll-2] o.example.controller.RSocketController : [connect.setup]Client connection: 96ff8fe7-416c-4607-9518-463114725a7a
received -5
received -4
received -3
received -2
received -1
received 0
received 1
received 2
received 3
received 4
下一篇文章会展示服务端如何主动调用客户端的函数。如有错误欢迎在评论区批评指正!