Provide AbstractSpan interface for the context.

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/AbstractTracerContext.java

 package org.skywalking.apm.agent.core.context;
 
-import org.skywalking.apm.agent.core.context.trace.Span;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 
 /**
  * The <code>AbstractTracerContext</code> represents the tracer context manager.
@@ -14,15 +14,15 @@ public interface AbstractTracerContext {
 
     String getGlobalTraceId();
 
-    Span createSpan(String operationName, boolean isLeaf);
+    AbstractSpan createSpan(String operationName, boolean isLeaf);
 
-    Span createSpan(String operationName, long startTime, boolean isLeaf);
+    AbstractSpan createSpan(String operationName, long startTime, boolean isLeaf);
 
-    Span activeSpan();
+    AbstractSpan activeSpan();
 
-    void stopSpan(Span span);
+    void stopSpan(AbstractSpan span);
 
-    void stopSpan(Span span, Long endTime);
+    void stopSpan(AbstractSpan span, Long endTime);
 
     void dispose();
 }

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/ContextManager.java

 package org.skywalking.apm.agent.core.context;
 
 import org.skywalking.apm.agent.core.boot.BootService;
-import org.skywalking.apm.agent.core.context.trace.Span;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.context.trace.TraceSegment;
 
 /**
@@ -12,7 +12,7 @@ import org.skywalking.apm.agent.core.context.trace.TraceSegment;
  * https://github.com/opentracing/specification/blob/master/specification.md#references-between-spans}
  * <p> Also, {@link
  * ContextManager} delegates to all {@link TracerContext}'s major methods: {@link TracerContext#createSpan(String,
- * boolean)}, {@link TracerContext#activeSpan()}, {@link TracerContext#stopSpan(Span)}
+ * boolean)}, {@link TracerContext#activeSpan()}, {@link AbstractTracerContext#stopSpan(org.skywalking.apm.agent.core.context.trace.AbstractSpan)}
  * <p>
  *
  * @author wusheng
@@ -55,23 +55,23 @@ public class ContextManager implements TracerContextListener, BootService, Ignor
         }
     }
 
-    public static Span createSpan(String operationName) {
+    public static AbstractSpan createSpan(String operationName) {
         return get().createSpan(operationName, false);
     }
 
-    public static Span createSpan(String operationName, long startTime) {
+    public static AbstractSpan createSpan(String operationName, long startTime) {
         return get().createSpan(operationName, startTime, false);
     }
 
-    public static Span createLeafSpan(String operationName) {
+    public static AbstractSpan createLeafSpan(String operationName) {
         return get().createSpan(operationName, true);
     }
 
-    public static Span createLeafSpan(String operationName, long startTime) {
+    public static AbstractSpan createLeafSpan(String operationName, long startTime) {
         return get().createSpan(operationName, startTime, true);
     }
 
-    public static Span activeSpan() {
+    public static AbstractSpan activeSpan() {
         return get().activeSpan();
     }
 

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/IgnoreTracerContext.java

@@ -2,7 +2,7 @@ package org.skywalking.apm.agent.core.context;
 
 import java.util.LinkedList;
 import java.util.List;
-import org.skywalking.apm.agent.core.context.trace.Span;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 
 /**
  * The <code>IgnoreTracerContext</code> represent a context should be ignored.
@@ -36,23 +36,23 @@ public class IgnoreTracerContext implements AbstractTracerContext {
     }
 
     @Override
-    public Span createSpan(String operationName, boolean isLeaf) {
+    public AbstractSpan createSpan(String operationName, boolean isLeaf) {
         stackDepth++;
         return null;
     }
 
     @Override
-    public Span createSpan(String operationName, long startTime, boolean isLeaf) {
+    public AbstractSpan createSpan(String operationName, long startTime, boolean isLeaf) {
         return createSpan(operationName, isLeaf);
     }
 
     @Override
-    public Span activeSpan() {
+    public AbstractSpan activeSpan() {
         return null;
     }
 
     @Override
-    public void stopSpan(Span span) {
+    public void stopSpan(AbstractSpan span) {
         stackDepth--;
         if (stackDepth == 0) {
 
@@ -60,7 +60,7 @@ public class IgnoreTracerContext implements AbstractTracerContext {
     }
 
     @Override
-    public void stopSpan(Span span, Long endTime) {
+    public void stopSpan(AbstractSpan span, Long endTime) {
         stopSpan(span);
     }
 

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/TracerContext.java

@@ -3,6 +3,7 @@ package org.skywalking.apm.agent.core.context;
 import java.util.LinkedList;
 import java.util.List;
 import org.skywalking.apm.agent.core.conf.Config;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.context.trace.LeafSpan;
 import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.context.trace.TraceSegment;
@@ -42,7 +43,7 @@ public final class TracerContext implements AbstractTracerContext {
      * @param operationName {@link Span#operationName}
      * @return the new active span.
      */
-    public Span createSpan(String operationName, boolean isLeaf) {
+    public AbstractSpan createSpan(String operationName, boolean isLeaf) {
         return this.createSpan(operationName, System.currentTimeMillis(), isLeaf);
     }
 
@@ -54,7 +55,7 @@ public final class TracerContext implements AbstractTracerContext {
      * @param isLeaf is true, if the span is a leaf in trace tree.
      * @return
      */
-    public Span createSpan(String operationName, long startTime, boolean isLeaf) {
+    public AbstractSpan createSpan(String operationName, long startTime, boolean isLeaf) {
         Span parentSpan = peek();
         Span span;
         if (parentSpan == null) {
@@ -82,7 +83,7 @@ public final class TracerContext implements AbstractTracerContext {
     /**
      * @return the active span of current context.
      */
-    public Span activeSpan() {
+    public AbstractSpan activeSpan() {
         Span span = peek();
         if (span == null) {
             throw new IllegalStateException("No active span.");
@@ -95,7 +96,7 @@ public final class TracerContext implements AbstractTracerContext {
      *
      * @param span to finish. It must the the top element of {@link #activeSpanStack}.
      */
-    public void stopSpan(Span span) {
+    public void stopSpan(AbstractSpan span) {
         stopSpan(span, System.currentTimeMillis());
     }
 
@@ -106,7 +107,7 @@ public final class TracerContext implements AbstractTracerContext {
         return segment.getRelatedGlobalTraces().get(0).get();
     }
 
-    public void stopSpan(Span span, Long endTime) {
+    public void stopSpan(AbstractSpan span, Long endTime) {
         Span lastSpan = peek();
         if (lastSpan.isLeaf()) {
             LeafSpan leafSpan = (LeafSpan)lastSpan;
@@ -147,7 +148,7 @@ public final class TracerContext implements AbstractTracerContext {
      */
     public void inject(ContextCarrier carrier) {
         carrier.setTraceSegmentId(this.segment.getTraceSegmentId());
-        Span span = this.activeSpan();
+        Span span = (Span)this.activeSpan();
         carrier.setSpanId(span.getSpanId());
         carrier.setApplicationCode(Config.Agent.APPLICATION_CODE);
         String host = span.getPeerHost();

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/tag/AbstractTag.java

 package org.skywalking.apm.agent.core.context.tag;
 
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.context.trace.Span;
 
 /**
@@ -22,7 +23,7 @@ public abstract class AbstractTag<T> {
         this.key = tagKey;
     }
 
-    protected abstract void set(Span span, T tagValue);
+    protected abstract void set(AbstractSpan span, T tagValue);
 
     /**
      * @return the key of this tag.

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/tag/BooleanTag.java

 package org.skywalking.apm.agent.core.context.tag;
 
-import org.skywalking.apm.agent.core.context.trace.Span;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 
 /**
  * Do the same thing as {@link StringTag}, just with a {@link Boolean} value.
@@ -17,7 +17,7 @@ public class BooleanTag extends AbstractTag<Boolean> {
     }
 
     @Override
-    public void set(Span span, Boolean tagValue) {
+    public void set(AbstractSpan span, Boolean tagValue) {
         span.setTag(key, tagValue);
     }
 

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/tag/IntTag.java

 package org.skywalking.apm.agent.core.context.tag;
 
-import org.skywalking.apm.agent.core.context.trace.Span;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 
 /**
  * Do the same thing as {@link StringTag}, just with a {@link Integer} value.
@@ -13,7 +13,7 @@ public class IntTag extends AbstractTag<Integer> {
     }
 
     @Override
-    public void set(Span span, Integer tagValue) {
+    public void set(AbstractSpan span, Integer tagValue) {
         span.setTag(super.key, tagValue);
     }
 

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/tag/StringTag.java

 package org.skywalking.apm.agent.core.context.tag;
 
-import org.skywalking.apm.agent.core.context.trace.Span;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 
 /**
  * A subclass of {@link AbstractTag},
@@ -14,7 +14,7 @@ public class StringTag extends AbstractTag<String> {
     }
 
     @Override
-    public void set(Span span, String tagValue) {
+    public void set(AbstractSpan span, String tagValue) {
         span.setTag(key, tagValue);
     }
 }

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/tag/Tags.java

 package org.skywalking.apm.agent.core.context.tag;
 
-import org.skywalking.apm.agent.core.context.trace.Span;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 
 /**
  * The span tags are supported by sky-walking engine.
@@ -52,15 +52,15 @@ public final class Tags {
         private static final String RPC_FRAMEWORK_LAYER = "rpc";
         private static final String HTTP_LAYER = "http";
 
-        public static void asDB(Span span) {
+        public static void asDB(AbstractSpan span) {
             SPAN_LAYER_TAG.set(span, DB_LAYER);
         }
 
-        public static void asRPCFramework(Span span) {
+        public static void asRPCFramework(AbstractSpan span) {
             SPAN_LAYER_TAG.set(span, RPC_FRAMEWORK_LAYER);
         }
 
-        public static void asHttp(Span span) {
+        public static void asHttp(AbstractSpan span) {
             SPAN_LAYER_TAG.set(span, HTTP_LAYER);
         }
     }

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/trace/AbstractSpan.java

+package org.skywalking.apm.agent.core.context.trace;
+
+import java.util.Map;
+
+/**
+ * The <code>AbstractSpan</code> represents the span's skeleton,
+ * which contains all open methods.
+ *
+ * @author wusheng
+ */
+public interface AbstractSpan {
+    AbstractSpan setOperationName(String operationName);
+
+    void setPeerHost(String peerHost);
+
+    void setPort(int port);
+
+    void setPeers(String peers);
+
+    AbstractSpan setTag(String key, String value);
+
+    AbstractSpan setTag(String key, boolean value);
+
+    AbstractSpan setTag(String key, Integer value);
+
+    AbstractSpan log(Map<String, String> fields);
+
+    AbstractSpan log(Throwable t);
+
+    AbstractSpan log(String event);
+}

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/trace/Span.java

@@ -32,7 +32,7 @@ import org.skywalking.apm.util.StringUtil;
  * Created by wusheng on 2017/2/17.
  */
 @JsonAdapter(Span.Serializer.class)
-public class Span {
+public class Span implements AbstractSpan {
     private static Gson SERIALIZATION_GSON = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();
 
     private int spanId;
@@ -111,7 +111,7 @@ public class Span {
         this.spanId = spanId;
         this.parentSpanId = parentSpanId;
         this.startTime = startTime;
-        this.operationName = operationName;
+        this.setOperationName(operationName);
     }
 
     /**
@@ -192,10 +192,12 @@ public class Span {
 
     /**
      * Sets the string name for the logical operation this span represents.
+     * These is one scenario, which trigger context switch.
+     * 1) the operations ends with the defined suffix, see {@link Config.Agent#IGNORE_SUFFIX}
      *
      * @return this Span instance, for chaining
      */
-    public Span setOperationName(String operationName) {
+    public AbstractSpan setOperationName(String operationName) {
         this.operationName = operationName;
         if (this.spanId == 0) {
             if (operationName != null) {

apm-sniffer/apm-agent-core/src/test/java/org/skywalking/apm/agent/core/context/ContextManagerTestCase.java

@@ -5,9 +5,9 @@ import org.junit.Assert;
 import org.junit.BeforeClass;
 import org.junit.Test;
 import org.skywalking.apm.agent.core.boot.ServiceManager;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.trace.TraceSegment;
 import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
+import org.skywalking.apm.agent.core.context.trace.TraceSegment;
 
 /**
  * Created by wusheng on 2017/2/19.
@@ -20,7 +20,7 @@ public class ContextManagerTestCase {
 
     @Test
     public void testDelegateToTracerContext() {
-        Span span = ContextManager.createSpan("serviceA");
+        AbstractSpan span = ContextManager.createSpan("serviceA");
         Tags.COMPONENT.set(span, "test");
 
         Assert.assertEquals(span, ContextManager.activeSpan());

apm-sniffer/apm-agent-core/src/test/java/org/skywalking/apm/agent/core/context/TracerContextTestCase.java

 package org.skywalking.apm.agent.core.context;
 
+import java.util.LinkedList;
+import java.util.List;
 import org.junit.After;
 import org.junit.Assert;
 import org.junit.Test;
-import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.context.ids.DistributedTraceId;
 import org.skywalking.apm.agent.core.context.ids.PropagatedTraceId;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
+import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.context.trace.TraceSegment;
 
-import java.util.LinkedList;
-import java.util.List;
-
 /**
  * Created by wusheng on 2017/2/19.
  */
@@ -18,7 +18,7 @@ public class TracerContextTestCase {
     @Test
     public void testSpanLifeCycle() {
         TracerContext context = new TracerContext();
-        Span span = context.createSpan("/serviceA", false);
+        AbstractSpan span = context.createSpan("/serviceA", false);
 
         Assert.assertEquals(span, context.activeSpan());
 
@@ -34,8 +34,8 @@ public class TracerContextTestCase {
     @Test
     public void testChildOfSpan() {
         TracerContext context = new TracerContext();
-        Span serviceSpan = context.createSpan("/serviceA", false);
-        Span dbSpan = context.createSpan("db/preparedStatement/execute", false);
+        AbstractSpan serviceSpan = context.createSpan("/serviceA", false);
+        AbstractSpan dbSpan = context.createSpan("db/preparedStatement/execute", false);
 
         Assert.assertEquals(dbSpan, context.activeSpan());
 
@@ -59,8 +59,8 @@ public class TracerContextTestCase {
     @Test
     public void testInject() {
         TracerContext context = new TracerContext();
-        Span serviceSpan = context.createSpan("/serviceA", false);
-        Span dbSpan = context.createSpan("db/preparedStatement/execute", false);
+        AbstractSpan serviceSpan = context.createSpan("/serviceA", false);
+        AbstractSpan dbSpan = context.createSpan("db/preparedStatement/execute", false);
         dbSpan.setPeerHost("127.0.0.1");
         dbSpan.setPort(8080);
 
@@ -86,7 +86,7 @@ public class TracerContextTestCase {
 
         TracerContext context = new TracerContext();
         context.extract(carrier);
-        Span span = context.createSpan("/serviceC", false);
+        AbstractSpan span = context.createSpan("/serviceC", false);
 
         TracerContext.ListenerManager.add(TestTracerContextListener.INSTANCE);
         final TraceSegment[] finishedSegmentCarrier = TestTracerContextListener.INSTANCE.finishedSegmentCarrier;

apm-sniffer/apm-sdk-plugin/dubbo-plugin/src/main/java/org/skywalking/apm/plugin/dubbo/DubboInterceptor.java

@@ -8,14 +8,14 @@ import com.alibaba.dubbo.rpc.RpcContext;
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.context.ContextCarrier;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
 import org.skywalking.apm.plugin.dubbox.BugFixActive;
 import org.skywalking.apm.plugin.dubbox.SWBaseBean;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.tag.Tags;
 
 /**
  * {@link DubboInterceptor} define how to enhance class {@link com.alibaba.dubbo.monitor.support.MonitorFilter#invoke(Invoker,
@@ -50,7 +50,7 @@ public class DubboInterceptor implements InstanceMethodsAroundInterceptor {
         boolean isConsumer = rpcContext.isConsumerSide();
         URL requestURL = invoker.getUrl();
 
-        Span span = ContextManager.createSpan(generateOperationName(requestURL, invocation));
+        AbstractSpan span = ContextManager.createSpan(generateOperationName(requestURL, invocation));
         Tags.URL.set(span, generateRequestURL(requestURL, invocation));
         Tags.COMPONENT.set(span, DUBBO_COMPONENT);
         Tags.SPAN_LAYER.asRPCFramework(span);
@@ -111,7 +111,7 @@ public class DubboInterceptor implements InstanceMethodsAroundInterceptor {
      * Log the throwable, which occurs in Dubbo RPC service.
      */
     private void dealException(Throwable throwable) {
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         Tags.ERROR.set(span, true);
         span.log(throwable);
     }

apm-sniffer/apm-sdk-plugin/feign-default-http-9.x-plugin/src/main/java/org/skywalking/apm/plugin/feign/http/v9/DefaultHttpClientInterceptor.java

@@ -14,12 +14,13 @@ import java.util.Map;
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.context.ContextCarrier;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
+import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.tag.Tags;
 
 /**
  * {@link DefaultHttpClientInterceptor} intercept the default implementation of http calls by the Feign.
@@ -46,7 +47,7 @@ public class DefaultHttpClientInterceptor implements InstanceMethodsAroundInterc
         Request request = (Request)interceptorContext.allArguments()[0];
 
         URL url = new URL(request.url());
-        Span span = ContextManager.createSpan(request.url());
+        AbstractSpan span = ContextManager.createSpan(request.url());
         span.setPeerHost(url.getHost());
         span.setPort(url.getPort());
         Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);
@@ -91,7 +92,7 @@ public class DefaultHttpClientInterceptor implements InstanceMethodsAroundInterc
         Response response = (Response)ret;
         int statusCode = response.status();
 
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         if (statusCode >= 400) {
             Tags.ERROR.set(span, true);
         }

apm-sniffer/apm-sdk-plugin/httpClient-4.x-plugin/src/main/java/org/skywalking/apm/plugin/httpClient/v4/HttpClientExecuteInterceptor.java

 package org.skywalking.apm.plugin.httpClient.v4;
 
-import org.apache.http.*;
+import java.net.MalformedURLException;
+import java.net.URL;
+import org.apache.http.Header;
+import org.apache.http.HttpHost;
+import org.apache.http.HttpRequest;
+import org.apache.http.HttpResponse;
+import org.apache.http.StatusLine;
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.context.ContextCarrier;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.tag.Tags;
-
-import java.net.MalformedURLException;
-import java.net.URL;
 
 /**
  * {@link HttpClientExecuteInterceptor} transport the trace context by call {@link HttpRequest#setHeader(Header)},
@@ -33,7 +36,7 @@ public class HttpClientExecuteInterceptor implements InstanceMethodsAroundInterc
         }
         HttpHost httpHost = (HttpHost)allArguments[0];
         HttpRequest httpRequest = (HttpRequest)allArguments[1];
-        Span span = createSpan(httpRequest);
+        AbstractSpan span = createSpan(httpRequest);
         span.setPeerHost(httpHost.getHostName());
         span.setPort(httpHost.getPort());
         Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);
@@ -58,8 +61,8 @@ public class HttpClientExecuteInterceptor implements InstanceMethodsAroundInterc
     /**
      * Create span.
      */
-    private Span createSpan(HttpRequest httpRequest) {
-        Span span;
+    private AbstractSpan createSpan(HttpRequest httpRequest) {
+        AbstractSpan span;
         try {
             URL url = new URL(httpRequest.getRequestLine().getUri());
             span = ContextManager.createSpan(url.getPath());
@@ -79,7 +82,7 @@ public class HttpClientExecuteInterceptor implements InstanceMethodsAroundInterc
 
         HttpResponse response = (HttpResponse)ret;
         int statusCode = response.getStatusLine().getStatusCode();
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         if (statusCode != 200) {
             Tags.ERROR.set(span, true);
         }

apm-sniffer/apm-sdk-plugin/jdbc-plugin/src/main/java/org/skywalking/apm/plugin/jdbc/CallableStatementTracing.java

 package org.skywalking.apm.plugin.jdbc;
 
+import java.sql.SQLException;
 import org.skywalking.apm.agent.core.context.ContextManager;
-import org.skywalking.apm.util.StringUtil;
-import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.context.tag.Tags;
-
-import java.sql.SQLException;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
+import org.skywalking.apm.agent.core.context.trace.Span;
+import org.skywalking.apm.util.StringUtil;
 
 /**
  * {@link CallableStatementTracing} create span with the {@link Span#operationName} start with
@@ -21,7 +21,7 @@ public class CallableStatementTracing {
                                 ConnectionInfo connectInfo, String method, String sql, Executable<R> exec)
         throws SQLException {
         try {
-            Span span = ContextManager.createSpan(connectInfo.getDBType() + "/JDBI/CallableStatement/" + method);
+            AbstractSpan span = ContextManager.createSpan(connectInfo.getDBType() + "/JDBI/CallableStatement/" + method);
             Tags.DB_TYPE.set(span, "sql");
             Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);
             Tags.DB_INSTANCE.set(span, connectInfo.getDatabaseName());
@@ -36,7 +36,7 @@ public class CallableStatementTracing {
             }
             return exec.exe(realStatement, sql);
         } catch (SQLException e) {
-            Span span = ContextManager.activeSpan();
+            AbstractSpan span = ContextManager.activeSpan();
             Tags.ERROR.set(span, true);
             span.log(e);
             throw e;

apm-sniffer/apm-sdk-plugin/jdbc-plugin/src/main/java/org/skywalking/apm/plugin/jdbc/ConnectionTracing.java

 package org.skywalking.apm.plugin.jdbc;
 
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.util.StringUtil;
 import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.context.tag.Tags;
@@ -21,7 +22,7 @@ public class ConnectionTracing {
                                 ConnectionInfo connectInfo, String method, String sql, Executable<R> exec)
         throws SQLException {
         try {
-            Span span = ContextManager.createSpan(connectInfo.getDBType() + "/JDBI/Connection/" + method);
+            AbstractSpan span = ContextManager.createSpan(connectInfo.getDBType() + "/JDBI/Connection/" + method);
             Tags.DB_TYPE.set(span, "sql");
             Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);
             Tags.DB_INSTANCE.set(span, connectInfo.getDatabaseName());
@@ -36,7 +37,7 @@ public class ConnectionTracing {
             }
             return exec.exe(realConnection, sql);
         } catch (SQLException e) {
-            Span span = ContextManager.activeSpan();
+            AbstractSpan span = ContextManager.activeSpan();
             Tags.ERROR.set(span, true);
             span.log(e);
             throw e;

apm-sniffer/apm-sdk-plugin/jdbc-plugin/src/main/java/org/skywalking/apm/plugin/jdbc/PreparedStatementTracing.java

 package org.skywalking.apm.plugin.jdbc;
 
+import java.sql.SQLException;
 import org.skywalking.apm.agent.core.context.ContextManager;
-import org.skywalking.apm.util.StringUtil;
-import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.context.tag.Tags;
-
-import java.sql.SQLException;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
+import org.skywalking.apm.agent.core.context.trace.Span;
+import org.skywalking.apm.util.StringUtil;
 
 /**
  * {@link PreparedStatementTracing} create span with the {@link Span#operationName} start with
@@ -21,7 +21,7 @@ public class PreparedStatementTracing {
                                 ConnectionInfo connectInfo, String method, String sql, Executable<R> exec)
         throws SQLException {
         try {
-            Span span = ContextManager.createSpan(connectInfo.getDBType() + "/JDBI/PreparedStatement/" + method);
+            AbstractSpan span = ContextManager.createSpan(connectInfo.getDBType() + "/JDBI/PreparedStatement/" + method);
             Tags.DB_TYPE.set(span, "sql");
             Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);
             Tags.DB_INSTANCE.set(span, connectInfo.getDatabaseName());
@@ -36,7 +36,7 @@ public class PreparedStatementTracing {
             Tags.SPAN_LAYER.asDB(span);
             return exec.exe(realStatement, sql);
         } catch (SQLException e) {
-            Span span = ContextManager.activeSpan();
+            AbstractSpan span = ContextManager.activeSpan();
             Tags.ERROR.set(span, true);
             span.log(e);
             throw e;

apm-sniffer/apm-sdk-plugin/jdbc-plugin/src/main/java/org/skywalking/apm/plugin/jdbc/StatementTracing.java

 package org.skywalking.apm.plugin.jdbc;
 
+import java.sql.SQLException;
 import org.skywalking.apm.agent.core.context.ContextManager;
-import org.skywalking.apm.util.StringUtil;
-import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.context.tag.Tags;
-
-import java.sql.SQLException;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
+import org.skywalking.apm.agent.core.context.trace.Span;
+import org.skywalking.apm.util.StringUtil;
 
 /**
  * {@link StatementTracing} create span with the {@link Span#operationName} start with
@@ -20,7 +20,7 @@ public class StatementTracing {
                                 ConnectionInfo connectInfo, String method, String sql, Executable<R> exec)
         throws SQLException {
         try {
-            Span span = ContextManager.createSpan(connectInfo.getDBType() + "/JDBI/Statement/" + method);
+            AbstractSpan span = ContextManager.createSpan(connectInfo.getDBType() + "/JDBI/Statement/" + method);
             Tags.DB_TYPE.set(span, "sql");
             Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);
             Tags.DB_INSTANCE.set(span, connectInfo.getDatabaseName());
@@ -35,7 +35,7 @@ public class StatementTracing {
             }
             return exec.exe(realStatement, sql);
         } catch (SQLException e) {
-            Span span = ContextManager.activeSpan();
+            AbstractSpan span = ContextManager.activeSpan();
             Tags.ERROR.set(span, true);
             span.log(e);
             throw e;

apm-sniffer/apm-sdk-plugin/jedis-2.x-plugin/src/main/java/org/skywalking/apm/plugin/jedis/v2/JedisMethodInterceptor.java

 package org.skywalking.apm.plugin.jedis.v2;
 
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.assist.NoConcurrencyAccessObject;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.tag.Tags;
 import org.skywalking.apm.util.StringUtil;
 
 /**
@@ -50,7 +50,7 @@ public class JedisMethodInterceptor extends NoConcurrencyAccessObject implements
     /**
      * set peer host information for the current active span.
      */
-    private void tagPeer(Span span, EnhancedClassInstanceContext context) {
+    private void tagPeer(AbstractSpan span, EnhancedClassInstanceContext context) {
         String redisHosts = (String)context.get(KEY_OF_REDIS_HOSTS);
         if (!StringUtil.isEmpty(redisHosts)) {
             span.setPeers((String)context.get(KEY_OF_REDIS_HOST));
@@ -78,7 +78,7 @@ public class JedisMethodInterceptor extends NoConcurrencyAccessObject implements
 
     @Override
     protected void enter(EnhancedClassInstanceContext context, InstanceMethodInvokeContext interceptorContext) {
-        Span span = ContextManager.createSpan("Jedis/" + interceptorContext.methodName());
+        AbstractSpan span = ContextManager.createSpan("Jedis/" + interceptorContext.methodName());
         Tags.COMPONENT.set(span, REDIS_COMPONENT);
         Tags.DB_TYPE.set(span, REDIS_COMPONENT);
         Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);

apm-sniffer/apm-sdk-plugin/mongodb-3.x-plugin/src/main/java/org/skywalking/apm/plugin/mongodb/v3/MongoDBMethodInterceptor.java

@@ -5,18 +5,35 @@ import com.mongodb.bulk.DeleteRequest;
 import com.mongodb.bulk.InsertRequest;
 import com.mongodb.bulk.UpdateRequest;
 import com.mongodb.bulk.WriteRequest;
-import com.mongodb.operation.*;
+import com.mongodb.operation.CountOperation;
+import com.mongodb.operation.CreateCollectionOperation;
+import com.mongodb.operation.CreateIndexesOperation;
+import com.mongodb.operation.CreateViewOperation;
+import com.mongodb.operation.DeleteOperation;
+import com.mongodb.operation.DistinctOperation;
+import com.mongodb.operation.FindAndDeleteOperation;
+import com.mongodb.operation.FindAndReplaceOperation;
+import com.mongodb.operation.FindAndUpdateOperation;
+import com.mongodb.operation.FindOperation;
+import com.mongodb.operation.GroupOperation;
+import com.mongodb.operation.InsertOperation;
+import com.mongodb.operation.ListCollectionsOperation;
+import com.mongodb.operation.MapReduceToCollectionOperation;
+import com.mongodb.operation.MapReduceWithInlineResultsOperation;
+import com.mongodb.operation.MixedBulkWriteOperation;
+import com.mongodb.operation.ReadOperation;
+import com.mongodb.operation.UpdateOperation;
+import com.mongodb.operation.WriteOperation;
+import java.util.List;
 import org.bson.BsonDocument;
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.tag.Tags;
-
-import java.util.List;
 
 /**
  * {@link MongoDBMethodInterceptor} intercept method of {@link com.mongodb.Mongo#execute(ReadOperation, ReadPreference)}
@@ -51,7 +68,7 @@ public class MongoDBMethodInterceptor implements InstanceMethodsAroundIntercepto
         Object[] arguments = interceptorContext.allArguments();
 
         String methodName = arguments[0].getClass().getSimpleName();
-        Span span = ContextManager.createSpan(METHOD + methodName);
+        AbstractSpan span = ContextManager.createSpan(METHOD + methodName);
         Tags.COMPONENT.set(span, MONGODB_COMPONENT);
         Tags.DB_TYPE.set(span, MONGODB_COMPONENT);
         Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);
@@ -66,7 +83,7 @@ public class MongoDBMethodInterceptor implements InstanceMethodsAroundIntercepto
     @Override
     public Object afterMethod(EnhancedClassInstanceContext context, InstanceMethodInvokeContext interceptorContext,
                               Object ret) {
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         span.setPeerHost((String)context.get(MONGODB_HOST));
         span.setPort((Integer)context.get(MONGODB_PORT));
         ContextManager.stopSpan();

apm-sniffer/apm-sdk-plugin/motan-plugin/src/main/java/org/skywalking/apm/plugin/motan/MotanConsumerInterceptor.java

@@ -6,14 +6,14 @@ import com.weibo.api.motan.rpc.URL;
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.context.ContextCarrier;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.ConstructorInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceConstructorInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.tag.Tags;
 
 /**
  * {@link MotanProviderInterceptor} create span by fetch request url from
@@ -45,7 +45,7 @@ public class MotanConsumerInterceptor implements InstanceConstructorInterceptor,
         URL url = (URL) context.get(KEY_NAME_OF_REQUEST_URL);
         Request request = (Request) interceptorContext.allArguments()[0];
         if (url != null) {
-            Span span = ContextManager.createSpan(generateOperationName(url, request));
+            AbstractSpan span = ContextManager.createSpan(generateOperationName(url, request));
             span.setPeerHost(url.getHost());
             span.setPort(url.getPort());
             Tags.COMPONENT.set(span, MOTAN_COMPONENT);
@@ -64,7 +64,7 @@ public class MotanConsumerInterceptor implements InstanceConstructorInterceptor,
                               Object ret) {
         Response response = (Response) ret;
         if (response != null && response.getException() != null) {
-            Span span = ContextManager.activeSpan();
+            AbstractSpan span = ContextManager.activeSpan();
             Tags.ERROR.set(span, true);
             span.log(response.getException());
         }

apm-sniffer/apm-sdk-plugin/motan-plugin/src/main/java/org/skywalking/apm/plugin/motan/MotanProviderInterceptor.java

@@ -5,13 +5,13 @@ import com.weibo.api.motan.rpc.Response;
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.context.ContextCarrier;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
 import org.skywalking.apm.util.StringUtil;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.tag.Tags;
 
 /**
  * Current trace segment will ref the trace segment if the serialized trace context that fetch from {@link
@@ -32,7 +32,7 @@ public class MotanProviderInterceptor implements InstanceMethodsAroundIntercepto
     public void beforeMethod(EnhancedClassInstanceContext context, InstanceMethodInvokeContext interceptorContext,
                              MethodInterceptResult result) {
         Request request = (Request) interceptorContext.allArguments()[0];
-        Span span = ContextManager.createSpan(generateViewPoint(request));
+        AbstractSpan span = ContextManager.createSpan(generateViewPoint(request));
         Tags.COMPONENT.set(span, MOTAN_COMPONENT);
         Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_SERVER);
         Tags.SPAN_LAYER.asRPCFramework(span);
@@ -48,7 +48,7 @@ public class MotanProviderInterceptor implements InstanceMethodsAroundIntercepto
                               Object ret) {
         Response response = (Response) ret;
         if (response != null && response.getException() != null) {
-            Span span = ContextManager.activeSpan();
+            AbstractSpan span = ContextManager.activeSpan();
             span.log(response.getException());
             Tags.ERROR.set(span, true);
         }

apm-sniffer/apm-sdk-plugin/okhttp-3.x-plugin/src/main/java/org/skywalking/apm/plugin/okhttp/v3/RealCallInterceptor.java

@@ -9,14 +9,15 @@ import okhttp3.Response;
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.context.ContextCarrier;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
+import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.ConstructorInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceConstructorInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.tag.Tags;
 
 /**
  * {@link RealCallInterceptor} intercept the synchronous http calls by the client of okhttp.
@@ -57,7 +58,7 @@ public class RealCallInterceptor implements InstanceMethodsAroundInterceptor, In
         MethodInterceptResult result) throws Throwable {
         Request request = (Request)context.get(REQUEST_CONTEXT_KEY);
 
-        Span span = ContextManager.createSpan(request.url().uri().toString());
+        AbstractSpan span = ContextManager.createSpan(request.url().uri().toString());
         span.setPeerHost(request.url().host());
         span.setPort(request.url().port());
         Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);
@@ -96,7 +97,7 @@ public class RealCallInterceptor implements InstanceMethodsAroundInterceptor, In
         Response response = (Response)ret;
         int statusCode = response.code();
 
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         if (statusCode >= 400) {
             Tags.ERROR.set(span, true);
         }

apm-sniffer/apm-sdk-plugin/resin-3.x-plugin/src/main/java/org/skywalking/apm/plugin/resin/v3/ResinV3Interceptor.java

@@ -5,12 +5,12 @@ import com.caucho.server.http.HttpResponse;
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.context.ContextCarrier;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.tag.Tags;
 import org.skywalking.apm.util.StringUtil;
 
 /**
@@ -30,7 +30,7 @@ public class ResinV3Interceptor implements InstanceMethodsAroundInterceptor {
         MethodInterceptResult result) {
         Object[] args = interceptorContext.allArguments();
         CauchoRequest request = (CauchoRequest)args[0];
-        Span span = ContextManager.createSpan(request.getPageURI());
+        AbstractSpan span = ContextManager.createSpan(request.getPageURI());
         Tags.COMPONENT.set(span, RESIN_COMPONENT);
         span.setPeerHost(request.getServerName());
         span.setPort(request.getServerPort());
@@ -65,7 +65,7 @@ public class ResinV3Interceptor implements InstanceMethodsAroundInterceptor {
     public Object afterMethod(EnhancedClassInstanceContext context, InstanceMethodInvokeContext interceptorContext,
         Object ret) {
         HttpResponse response = (HttpResponse)interceptorContext.allArguments()[1];
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         Tags.STATUS_CODE.set(span, response.getStatusCode());
 
         if (response.getStatusCode() != 200) {
@@ -78,7 +78,7 @@ public class ResinV3Interceptor implements InstanceMethodsAroundInterceptor {
     @Override
     public void handleMethodException(Throwable t, EnhancedClassInstanceContext context,
         InstanceMethodInvokeContext interceptorContext) {
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         span.log(t);
         Tags.ERROR.set(span, true);
     }

apm-sniffer/apm-sdk-plugin/resin-4.x-plugin/src/main/java/org/skywalking/apm/plugin/resin/v4/ResinV4Interceptor.java

@@ -5,12 +5,12 @@ import javax.servlet.http.HttpServletResponse;
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.context.ContextCarrier;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.tag.Tags;
 import org.skywalking.apm.util.StringUtil;
 
 /**
@@ -27,7 +27,7 @@ public class ResinV4Interceptor implements InstanceMethodsAroundInterceptor {
         MethodInterceptResult result) {
         Object[] args = interceptorContext.allArguments();
         CauchoRequest request = (CauchoRequest)args[0];
-        Span span = ContextManager.createSpan(request.getPageURI());
+        AbstractSpan span = ContextManager.createSpan(request.getPageURI());
         Tags.COMPONENT.set(span, RESIN_COMPONENT);
         span.setPeerHost(request.getServerName());
         span.setPort(request.getServerPort());
@@ -62,7 +62,7 @@ public class ResinV4Interceptor implements InstanceMethodsAroundInterceptor {
     public Object afterMethod(EnhancedClassInstanceContext context, InstanceMethodInvokeContext interceptorContext,
         Object ret) {
         HttpServletResponse response = (HttpServletResponse)interceptorContext.allArguments()[1];
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         Tags.STATUS_CODE.set(span, response.getStatus());
 
         if (response.getStatus() != 200) {
@@ -75,7 +75,7 @@ public class ResinV4Interceptor implements InstanceMethodsAroundInterceptor {
     @Override
     public void handleMethodException(Throwable t, EnhancedClassInstanceContext context,
         InstanceMethodInvokeContext interceptorContext) {
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         span.log(t);
         Tags.ERROR.set(span, true);
     }

apm-sniffer/apm-sdk-plugin/tomcat-7.x-8.x-plugin/src/main/java/org/skywalking/apm/plugin/tomcat78x/TomcatInterceptor.java

 package org.skywalking.apm.plugin.tomcat78x;
 
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.context.ContextCarrier;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
+import org.skywalking.apm.agent.core.context.trace.TraceSegment;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
 import org.skywalking.apm.util.StringUtil;
-import org.skywalking.apm.agent.core.context.trace.Span;
-import org.skywalking.apm.agent.core.context.trace.TraceSegment;
-import org.skywalking.apm.agent.core.context.tag.Tags;
-
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
 
 /**
  * {@link TomcatInterceptor} fetch the serialized context data by using {@link HttpServletRequest#getHeader(String)}.
@@ -40,7 +39,7 @@ public class TomcatInterceptor implements InstanceMethodsAroundInterceptor {
         Object[] args = interceptorContext.allArguments();
         HttpServletRequest request = (HttpServletRequest) args[0];
 
-        Span span = ContextManager.createSpan(request.getRequestURI());
+        AbstractSpan span = ContextManager.createSpan(request.getRequestURI());
         Tags.COMPONENT.set(span, TOMCAT_COMPONENT);
         span.setPeerHost(fetchRequestPeerHost(request));
         span.setPort(request.getRemotePort());
@@ -59,7 +58,7 @@ public class TomcatInterceptor implements InstanceMethodsAroundInterceptor {
                               Object ret) {
         HttpServletResponse response = (HttpServletResponse) interceptorContext.allArguments()[1];
 
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         Tags.STATUS_CODE.set(span, response.getStatus());
 
         if (response.getStatus() != 200) {
@@ -73,7 +72,7 @@ public class TomcatInterceptor implements InstanceMethodsAroundInterceptor {
     @Override
     public void handleMethodException(Throwable t, EnhancedClassInstanceContext context,
                                       InstanceMethodInvokeContext interceptorContext) {
-        Span span = ContextManager.activeSpan();
+        AbstractSpan span = ContextManager.activeSpan();
         span.log(t);
         Tags.ERROR.set(span, true);
     }

apm-sniffer/apm-sniffer-mock/src/main/java/org/skywalking/apm/sniffer/mock/trace/builders/span/DubboSpanGenerator.java

 package org.skywalking.apm.sniffer.mock.trace.builders.span;
 
 import org.skywalking.apm.agent.core.context.ContextManager;
-import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 
 /**
  * The <code>DubboSpanGenerator</code> generates all possible spans, by tracing Dubbo rpc.
@@ -14,7 +14,7 @@ public class DubboSpanGenerator {
     public static class Client extends SpanGeneration {
         @Override
         protected void before() {
-            Span span = ContextManager.createSpan("/default_rpc/org.skywalking.apm.test.persistence.PersistenceService.query");
+            AbstractSpan span = ContextManager.createSpan("/default_rpc/org.skywalking.apm.test.persistence.PersistenceService.query");
             Tags.COMPONENT.set(span, "Dubbo");
             Tags.URL.set(span, "rest://192.168.1.8:20880/default_rpc/org.skywalking.apm.test.persistence.PersistenceService.query(String)");
             Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_SERVER);
@@ -32,7 +32,7 @@ public class DubboSpanGenerator {
     public static class Server extends SpanGeneration {
         @Override
         protected void before() {
-            Span span = ContextManager.createSpan("/default_rpc/org.skywalking.apm.test.persistence.PersistenceService.query");
+            AbstractSpan span = ContextManager.createSpan("/default_rpc/org.skywalking.apm.test.persistence.PersistenceService.query");
             Tags.COMPONENT.set(span, "Dubbo");
             Tags.URL.set(span, "rest://192.168.1.8:20880/default_rpc/org.skywalking.apm.test.persistence.PersistenceService.query(String)");
             Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);

apm-sniffer/apm-sniffer-mock/src/main/java/org/skywalking/apm/sniffer/mock/trace/builders/span/MySQLGenerator.java

 package org.skywalking.apm.sniffer.mock.trace.builders.span;
 
 import org.skywalking.apm.agent.core.context.ContextManager;
-import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 
 /**
  * The <code>MySQLGenerator</code> generates all possible spans, by tracing mysql client access.
@@ -13,7 +13,7 @@ public class MySQLGenerator {
     public static class Query extends SpanGeneration {
         @Override
         protected void before() {
-            Span span = ContextManager.createSpan("mysql/jdbi/statement/executeQuery");
+            AbstractSpan span = ContextManager.createSpan("mysql/jdbi/statement/executeQuery");
             Tags.COMPONENT.set(span, "Mysql");
             Tags.SPAN_KIND.set(span, Tags.SPAN_KIND_CLIENT);
             span.setPeerHost("10.5.34.18");

apm-sniffer/apm-sniffer-mock/src/main/java/org/skywalking/apm/sniffer/mock/trace/builders/span/TomcatSpanGenerator.java

 package org.skywalking.apm.sniffer.mock.trace.builders.span;
 
 import org.skywalking.apm.agent.core.context.ContextManager;
-import org.skywalking.apm.agent.core.context.trace.Span;
 import org.skywalking.apm.agent.core.context.tag.Tags;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 
 /**
  * The <code>TomcatSpanGenerator</code> generate all possible spans, by tracing Tomcat.
@@ -15,7 +15,7 @@ public class TomcatSpanGenerator {
 
         @Override
         protected void before() {
-            Span webSpan = ContextManager.createSpan("/web/serviceA");
+            AbstractSpan webSpan = ContextManager.createSpan("/web/serviceA");
             Tags.COMPONENT.set(webSpan, "Tomcat");
             Tags.URL.set(webSpan, "http://10.21.9.35/web/serviceA");
             Tags.SPAN_KIND.set(webSpan, Tags.SPAN_KIND_SERVER);
@@ -26,7 +26,7 @@ public class TomcatSpanGenerator {
 
         @Override
         protected void after() {
-            Span webSpan = ContextManager.activeSpan();
+            AbstractSpan webSpan = ContextManager.activeSpan();
             Tags.STATUS_CODE.set(webSpan, 200);
             ContextManager.stopSpan();
         }
@@ -37,7 +37,7 @@ public class TomcatSpanGenerator {
 
         @Override
         protected void before() {
-            Span webSpan = ContextManager.createSpan("/web/service/unknown");
+            AbstractSpan webSpan = ContextManager.createSpan("/web/service/unknown");
             Tags.COMPONENT.set(webSpan, "Tomcat");
             Tags.URL.set(webSpan, "http://10.21.9.35/web/unknown");
             Tags.SPAN_KIND.set(webSpan, Tags.SPAN_KIND_SERVER);
@@ -48,7 +48,7 @@ public class TomcatSpanGenerator {
 
         @Override
         protected void after() {
-            Span webSpan = ContextManager.activeSpan();
+            AbstractSpan webSpan = ContextManager.activeSpan();
             Tags.STATUS_CODE.set(webSpan, 404);
             Tags.ERROR.set(webSpan, true);
             ContextManager.stopSpan();
@@ -60,7 +60,7 @@ public class TomcatSpanGenerator {
 
         @Override
         protected void before() {
-            Span webSpan = ContextManager.createSpan("/web/error/service");
+            AbstractSpan webSpan = ContextManager.createSpan("/web/error/service");
             Tags.COMPONENT.set(webSpan, "Tomcat");
             Tags.URL.set(webSpan, "http://10.21.9.35/web/error/service");
             Tags.SPAN_KIND.set(webSpan, Tags.SPAN_KIND_SERVER);
@@ -71,7 +71,7 @@ public class TomcatSpanGenerator {
 
         @Override
         protected void after() {
-            Span webSpan = ContextManager.activeSpan();
+            AbstractSpan webSpan = ContextManager.activeSpan();
             Tags.STATUS_CODE.set(webSpan, 500);
             Tags.ERROR.set(webSpan, true);
             webSpan.log(new NumberFormatException("Can't convert 'abc' to int."));

apm-sniffer/apm-toolkit-activation/apm-toolkit-opentracing-activation/src/main/java/org/skywalking/apm/toolkit/activation/opentracing/span/interceptor/SpanNewInstanceInterceptor.java

 package org.skywalking.apm.toolkit.activation.opentracing.span.interceptor;
 
+import java.util.Map;
 import org.skywalking.apm.agent.core.context.ContextManager;
+import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
 import org.skywalking.apm.agent.core.plugin.interceptor.EnhancedClassInstanceContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.ConstructorInvokeContext;
 import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceConstructorInterceptor;
 import org.skywalking.apm.toolkit.opentracing.SkyWalkingSpan;
-import org.skywalking.apm.agent.core.context.trace.Span;
-
-import java.util.Map;
 
 /**
  * Intercept {@link SkyWalkingSpan} constructor.
@@ -20,7 +19,7 @@ public class SpanNewInstanceInterceptor implements InstanceConstructorIntercepto
         String operationName = (String) allArguments[0];
         long startTime = (Long) allArguments[1];
         Map<String, String> tags = (Map<String, String>) allArguments[2];
-        Span span = ContextManager.createSpan(operationName, startTime);
+        AbstractSpan span = ContextManager.createSpan(operationName, startTime);
 
         for (Map.Entry<String, String> entry : tags.entrySet()) {
             span.setTag(entry.getKey(), entry.getValue());