[GitHub] [skywalking] ascrutae commented on a change in pull request #5086: Add support for spring webclient

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ascrutae commented on a change in pull request #5086:
URL: https://github.com/apache/skywalking/pull/5086#discussion_r455172724



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File path: test/plugin/scenarios/webflux-scenario/webflux-projectB-scenario/src/main/java/org/apache/skywalking/apm/testcase/sc/webflux/projectB/controller/TestWebclientController.java
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@@ -0,0 +1,47 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.apache.skywalking.apm.testcase.sc.webflux.projectB.controller;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.reactive.function.client.ExchangeStrategies;
+import org.springframework.web.reactive.function.client.WebClient;
+import reactor.core.publisher.Mono;
+
+@RestController
+public class TestWebclientController {
+
+    @Value("${projectB.host:localhost:18080}")
+    private String hostBAddress;
+
+    @RequestMapping("/testcase/webclient/ping")
+    public String ping() {
+        return "ok";
+    }
+
+    @RequestMapping("/testcase/webclient/test1")
+    public String test1() {
+        Mono<String> resp = WebClient.builder().exchangeStrategies(ExchangeStrategies.builder()
+                .build())
+                .build()
+                .get().uri("http://" + hostBAddress + "/testcase/webclient/ping")

Review comment:
        It's still not link because Controller and WebClient calling run in different threads and the WebClient plugin doesn't link the trace context. I suggest that you should save the `ContextSnapshot` when create WebClient Object and `continued` when WebClient send request.
   
   I also found another problem that the trace miss span about WebClient plugin,  In my case, the trace will miss the database span.
   ```java
    @RequestMapping("/testcase/webclient/test1")
       public String test1() {
           Mono<String> resp = WebClient.builder().exchangeStrategies(ExchangeStrategies.builder()
                   .build())
                   .build()
                   .get().uri("http://" + hostBAddress + "/testcase/webclient/ping")
                   .retrieve().bodyToMono(String.class);
           resp.subscribe(new Consumer<String>() {
               @Override
               public void accept(final String s) {
                   // read data from database 
               }
           });
           return "ok";
       }
   ```




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