diff --git a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/LogData.java b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/LogData.java
index b50468bdc..8cc662b8b 100644
--- a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/LogData.java
+++ b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/LogData.java
@@ -17,9 +17,9 @@ public class LogData {
 
     @Expose
     @SerializedName(value="fi")
-    private Map<String, ?> fields;
+    private Map<String, String> fields;
 
-    LogData(long time, Map<String, ?> fields) {
+    LogData(long time, Map<String, String> fields) {
         this.time = time;
         if(fields == null){
             throw new NullPointerException();
diff --git a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/Span.java b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/Span.java
index 57573fd4e..9ba226cf4 100644
--- a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/Span.java
+++ b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/Span.java
@@ -57,8 +57,16 @@ public class Span{
      * {@see https://github.com/opentracing/specification/blob/master/specification.md#set-a-span-tag}
      */
     @Expose
-    @SerializedName(value="ta")
-    private final Map<String, Object> tags;
+    @SerializedName(value="ts")
+    private final Map<String, String> tagsWithStr;
+
+    @Expose
+    @SerializedName(value="tb")
+    private final Map<String, Boolean> tagsWithBool;
+
+    @Expose
+    @SerializedName(value="ti")
+    private final Map<String, Integer> tagsWithInt;
 
     /**
      * Log is a concept from OpenTracing spec.
@@ -151,7 +159,9 @@ public class Span{
      * Create a new/empty span.
      */
     public Span() {
-        tags = new HashMap<String, Object>();
+        tagsWithStr = new HashMap<String, String>(5);
+        tagsWithBool = new HashMap<String, Boolean>(1);
+        tagsWithInt = new HashMap<String, Integer>(2);
         logs = new LinkedList<LogData>();
     }
 
@@ -194,17 +204,17 @@ public class Span{
      * @return this Span instance, for chaining
      */
     public final Span setTag(String key, String value) {
-        tags.put(key, value);
+        tagsWithStr.put(key, value);
         return this;
     }
 
     public final Span setTag(String key, boolean value) {
-        tags.put(key, value);
+        tagsWithBool.put(key, value);
         return this;
     }
 
-    public final Span setTag(String key, Number value) {
-        tags.put(key, value);
+    public final Span setTag(String key, Integer value) {
+        tagsWithInt.put(key, value);
         return this;
     }
 
@@ -214,7 +224,11 @@ public class Span{
      * @return
      */
     public final Map<String, Object> getTags() {
-        return Collections.unmodifiableMap(tags);
+        Map<String, Object> tags = new HashMap<String, Object>();
+        tags.putAll(tagsWithStr);
+        tags.putAll(tagsWithBool);
+        tags.putAll(tagsWithInt);
+        return tags;
     }
 
     /**
@@ -223,8 +237,16 @@ public class Span{
      * @param key the given tag key.
      * @return tag value.
      */
-    public Object getTag(String key) {
-        return tags.get(key);
+    public String getStrTag(String key) {
+        return tagsWithStr.get(key);
+    }
+
+    public Boolean getBoolTag(String key) {
+        return tagsWithBool.get(key);
+    }
+
+    public Integer getIntTag(String key) {
+        return tagsWithInt.get(key);
     }
 
     /**
@@ -250,7 +272,7 @@ public class Span{
      * @return the Span, for chaining
      * @see Span#log(String)
      */
-    public Span log(Map<String, ?> fields) {
+    public Span log(Map<String, String> fields) {
         logs.add(new LogData(System.currentTimeMillis(), fields));
         return this;
     }
diff --git a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/TraceSegment.java b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/TraceSegment.java
index d5c2edbcf..75e11cdcb 100644
--- a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/TraceSegment.java
+++ b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/TraceSegment.java
@@ -26,21 +26,21 @@ public class TraceSegment {
      * Every segment has its unique-global-id.
      */
     @Expose
-    @SerializedName(value="ts")
+    @SerializedName(value = "ts")
     private String traceSegmentId;
 
     /**
      * The start time of this trace segment.
      */
     @Expose
-    @SerializedName(value="st")
+    @SerializedName(value = "st")
     private long startTime;
 
     /**
      * The end time of this trace segment.
      */
     @Expose
-    @SerializedName(value="et")
+    @SerializedName(value = "et")
     private long endTime;
 
     /**
@@ -50,7 +50,7 @@ public class TraceSegment {
      * at this moment, we use this {@link #refs} to link them.
      */
     @Expose
-    @SerializedName(value="rs")
+    @SerializedName(value = "rs")
     private List<TraceSegmentRef> refs;
 
     /**
@@ -59,7 +59,7 @@ public class TraceSegment {
      * All active spans are hold and controlled by "skywalking-api" module.
      */
     @Expose
-    @SerializedName(value="ss")
+    @SerializedName(value = "ss")
     private List<Span> spans;
 
     /**
@@ -69,7 +69,7 @@ public class TraceSegment {
      * e.g. account_app, billing_app
      */
     @Expose
-    @SerializedName(value="ac")
+    @SerializedName(value = "ac")
     private String applicationCode;
 
     /**
@@ -86,9 +86,19 @@ public class TraceSegment {
      * multi {@link TraceSegment}s, only using {@link #refs} is not enough for analysis and ui.
      */
     @Expose
-    @SerializedName(value="gt")
+    @SerializedName(value = "gt")
     private DistributedTraceIds relatedGlobalTraces;
 
+    /**
+     * The <code>sampled</code> is a flag, which represent, when this {@link TraceSegment} finished, it need to be send
+     * to Collector.
+     *
+     * Its value depends on SamplingService. True, by default.
+     *
+     * This value is not serialized.
+     */
+    private boolean sampled;
+
     /**
      * Create a trace segment, by given segmentId.
      * This segmentId is generated by TraceSegmentRef, AKA, from tracer/agent module.
@@ -107,6 +117,7 @@ public class TraceSegment {
         this.spans = new LinkedList<Span>();
         this.relatedGlobalTraces = new DistributedTraceIds();
         this.relatedGlobalTraces.append(new NewDistributedTraceId());
+        this.sampled = true;
     }
 
     /**
@@ -118,7 +129,7 @@ public class TraceSegment {
         if (refs == null) {
             refs = new LinkedList<TraceSegmentRef>();
         }
-        if(!refs.contains(refSegment)){
+        if (!refs.contains(refSegment)) {
             refs.add(refSegment);
         }
     }
@@ -183,6 +194,14 @@ public class TraceSegment {
         return applicationCode;
     }
 
+    public boolean isSampled() {
+        return sampled;
+    }
+
+    public void setSampled(boolean sampled) {
+        this.sampled = sampled;
+    }
+
     @Override
     public String toString() {
         return "TraceSegment{" +
diff --git a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/AbstractTag.java b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/AbstractTag.java
index 9ffeea26e..e023ac274 100644
--- a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/AbstractTag.java
+++ b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/AbstractTag.java
@@ -7,7 +7,7 @@ import com.a.eye.skywalking.trace.Span;
  * All span's tags inherit from {@link AbstractTag},
  * which provide an easy way to
  *      {@link Span#setTag(String, String)} ,
- *      {@link Span#setTag(String, Number)} ,
+ *      {@link Span#setTag(String, Integer)}
  *      {@link Span#setTag(String, boolean)} ,
  *
  * Created by wusheng on 2017/2/17.
diff --git a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/BooleanTag.java b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/BooleanTag.java
index 9f3a780f2..20c83af35 100644
--- a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/BooleanTag.java
+++ b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/BooleanTag.java
@@ -30,13 +30,11 @@ public class BooleanTag extends AbstractTag<Boolean> {
      */
     @Override
     public Boolean get(Span span) {
-        Object tagValue = span.getTag(super.key);
+        Boolean tagValue = span.getBoolTag(super.key);
         if (tagValue == null) {
             return defaultValue;
-        } else if (tagValue instanceof Boolean) {
-            return (Boolean) tagValue;
         } else {
-            return Boolean.valueOf(tagValue.toString());
+            return tagValue;
         }
     }
 }
diff --git a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/IntTag.java b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/IntTag.java
index 8af1fec9a..cc6b36b2e 100644
--- a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/IntTag.java
+++ b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/IntTag.java
@@ -26,13 +26,11 @@ public class IntTag extends AbstractTag<Integer> {
      */
     @Override
     public Integer get(Span span) {
-        Object tagValue = span.getTag(super.key);
+        Integer tagValue = span.getIntTag(super.key);
         if (tagValue == null) {
             return null;
-        } else if(tagValue instanceof Integer){
-            return (Integer)tagValue;
-        }else {
-            return Integer.valueOf(tagValue.toString());
+        } else {
+            return tagValue;
         }
     }
 }
diff --git a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/ShortTag.java b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/ShortTag.java
index ebd93a607..b7e8f6585 100644
--- a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/ShortTag.java
+++ b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/ShortTag.java
@@ -14,7 +14,7 @@ public class ShortTag extends AbstractTag<Short> {
 
     @Override
     public void set(Span span, Short tagValue) {
-        span.setTag(super.key, tagValue);
+        span.setTag(super.key, (int)tagValue.shortValue());
     }
 
     /**
@@ -25,12 +25,10 @@ public class ShortTag extends AbstractTag<Short> {
      * @return tag value
      */
     @Override public Short get(Span span) {
-        Object tagValue = span.getTag(super.key);
+        Integer tagValue = span.getIntTag(super.key);
         if (tagValue == null) {
             return null;
-        } else if(tagValue instanceof Short){
-            return (Short)tagValue;
-        }else {
+        } else {
             return Short.valueOf(tagValue.toString());
         }
     }
diff --git a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/StringTag.java b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/StringTag.java
index 229521287..e76825c9c 100644
--- a/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/StringTag.java
+++ b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/tag/StringTag.java
@@ -19,6 +19,6 @@ public class StringTag extends AbstractTag<String> {
     }
 
     @Override public String get(Span span) {
-        return (String)span.getTag(super.key);
+        return span.getStrTag(super.key);
     }
 }
diff --git a/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/LogDataTestCase.java b/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/LogDataTestCase.java
index 316c278ac..f2f616d22 100644
--- a/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/LogDataTestCase.java
+++ b/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/LogDataTestCase.java
@@ -11,7 +11,7 @@ import org.junit.Test;
 public class LogDataTestCase {
     @Test
     public void testHoldValue(){
-        Map<String, ?> fields = new HashMap<String, String>();
+        Map<String, String> fields = new HashMap<String, String>();
         LogData logData = new LogData(123L, fields);
 
         Assert.assertEquals(123, logData.getTime());
diff --git a/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/tag/TagsTest.java b/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/tag/TagsTest.java
index 3bb2b4d55..7cb908ffc 100644
--- a/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/tag/TagsTest.java
+++ b/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/tag/TagsTest.java
@@ -12,13 +12,13 @@ public class TagsTest {
     public void testLayer(){
         Span span = new Span(1, "/test");
         Tags.SPAN_LAYER.asDB(span);
-        Assert.assertEquals("db", span.getTag("span.layer"));
+        Assert.assertEquals("db", span.getStrTag("span.layer"));
 
         Tags.SPAN_LAYER.asRPCFramework(span);
-        Assert.assertEquals("rpc", span.getTag("span.layer"));
+        Assert.assertEquals("rpc", span.getStrTag("span.layer"));
 
         Tags.SPAN_LAYER.asHttp(span);
-        Assert.assertEquals("http", span.getTag("span.layer"));
+        Assert.assertEquals("http", span.getStrTag("span.layer"));
     }
 
     @Test
diff --git a/skywalking-sniffer/skywalking-agent/dependency-reduced-pom.xml b/skywalking-sniffer/skywalking-agent/dependency-reduced-pom.xml
index 014bb63e4..0d5b89395 100644
--- a/skywalking-sniffer/skywalking-agent/dependency-reduced-pom.xml
+++ b/skywalking-sniffer/skywalking-agent/dependency-reduced-pom.xml
@@ -36,23 +36,20 @@
                   </manifestEntries>
                 </transformer>
               </transformers>
+              <artifactSet>
+                <excludes>
+                  <exclude>com.lmax:*</exclude>
+                  <exclude>org.apache.httpcomponents:*</exclude>
+                  <exclude>commons-logging:*</exclude>
+                  <exclude>commons-codec:*</exclude>
+                  <exclude>*:gson</exclude>
+                </excludes>
+              </artifactSet>
               <relocations>
                 <relocation>
                   <pattern>${shade.net.bytebuddy.source}</pattern>
                   <shadedPattern>${shade.net.bytebuddy.target}</shadedPattern>
                 </relocation>
-                <relocation>
-                  <pattern>${shade.com.lmax.disruptor.source}</pattern>
-                  <shadedPattern>${shade.com.lmax.disruptor.target}</shadedPattern>
-                </relocation>
-                <relocation>
-                  <pattern>${shade.com.google.source}</pattern>
-                  <shadedPattern>${shade.com.google.target}</shadedPattern>
-                </relocation>
-                <relocation>
-                  <pattern>${shade.org.apache.source}</pattern>
-                  <shadedPattern>${shade.org.apache.target}</shadedPattern>
-                </relocation>
               </relocations>
             </configuration>
           </execution>
@@ -61,6 +58,12 @@
     </plugins>
   </build>
   <dependencies>
+    <dependency>
+      <groupId>com.google.code.gson</groupId>
+      <artifactId>gson</artifactId>
+      <version>2.8.0</version>
+      <scope>compile</scope>
+    </dependency>
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
@@ -120,17 +123,11 @@
     </repository>
   </distributionManagement>
   <properties>
-    <shade.org.apache.source>org.apache</shade.org.apache.source>
-    <shade.package>com.a.eye.skywalking.dependencies</shade.package>
-    <shade.com.google.source>com.google</shade.com.google.source>
     <shade.net.bytebuddy.target>${shade.package}.${shade.net.bytebuddy.source}</shade.net.bytebuddy.target>
-    <shade.com.lmax.disruptor.target>${shade.package}.${shade.com.lmax.disruptor.source}</shade.com.lmax.disruptor.target>
+    <shade.package>com.a.eye.skywalking.dependencies</shade.package>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <shade.net.bytebuddy.source>net.bytebuddy</shade.net.bytebuddy.source>
-    <shade.com.google.target>${shade.package}.${shade.com.google.source}</shade.com.google.target>
-    <shade.org.apache.target>${shade.package}.${shade.org.apache.source}</shade.org.apache.target>
     <premain.class>com.a.eye.skywalking.agent.SkyWalkingAgent</premain.class>
-    <shade.com.lmax.disruptor.source>com.lmax.disruptor</shade.com.lmax.disruptor.source>
   </properties>
 </project>
 
diff --git a/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/conf/Config.java b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/conf/Config.java
index d13ad75e3..402b4be81 100644
--- a/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/conf/Config.java
+++ b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/conf/Config.java
@@ -8,6 +8,8 @@ public class Config {
         public static boolean IS_PREMAIN_MODE = false;
 
         public static String PATH = "";
+
+        public static int SAMPLING_RATE = 10000;
     }
 
     public static class Collector{
diff --git a/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/context/ContextCarrier.java b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/context/ContextCarrier.java
index 684922194..9c653518b 100644
--- a/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/context/ContextCarrier.java
+++ b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/context/ContextCarrier.java
@@ -42,6 +42,11 @@ public class ContextCarrier implements Serializable {
      */
     private List<DistributedTraceId> distributedTraceIds;
 
+    /**
+     * {@link TraceSegment#sampled}
+     */
+    private boolean sampled;
+
     /**
      * Serialize this {@link ContextCarrier} to a {@link String},
      * with '|' split.
@@ -54,7 +59,8 @@ public class ContextCarrier implements Serializable {
             this.getSpanId() + "",
             this.getApplicationCode(),
             this.getPeerHost(),
-            this.serializeDistributedTraceIds());
+            this.serializeDistributedTraceIds(),
+            this.isSampled() ? "1" : "0");
     }
 
     /**
@@ -64,14 +70,15 @@ public class ContextCarrier implements Serializable {
      */
     public ContextCarrier deserialize(String text) {
         if (text != null) {
-            String[] parts = text.split("\\|", 5);
-            if (parts.length == 5) {
+            String[] parts = text.split("\\|", 6);
+            if (parts.length == 6) {
                 try {
                     setSpanId(Integer.parseInt(parts[1]));
                     setTraceSegmentId(parts[0]);
                     setApplicationCode(parts[2]);
                     setPeerHost(parts[3]);
                     setDistributedTraceIds(deserializeDistributedTraceIds(parts[4]));
+                    setSampled("1".equals(parts[5]));
                 } catch (NumberFormatException e) {
 
                 }
@@ -129,6 +136,14 @@ public class ContextCarrier implements Serializable {
         return distributedTraceIds;
     }
 
+    public boolean isSampled() {
+        return sampled;
+    }
+
+    public void setSampled(boolean sampled) {
+        this.sampled = sampled;
+    }
+
     public void setDistributedTraceIds(List<DistributedTraceId> distributedTraceIds) {
         this.distributedTraceIds = distributedTraceIds;
     }
diff --git a/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/context/TracerContext.java b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/context/TracerContext.java
index 6229bd10e..a2a6c5b26 100644
--- a/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/context/TracerContext.java
+++ b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/context/TracerContext.java
@@ -1,6 +1,8 @@
 package com.a.eye.skywalking.api.context;
 
+import com.a.eye.skywalking.api.boot.ServiceManager;
 import com.a.eye.skywalking.api.conf.Config;
+import com.a.eye.skywalking.api.sampling.SamplingService;
 import com.a.eye.skywalking.trace.Span;
 import com.a.eye.skywalking.trace.TraceSegment;
 import com.a.eye.skywalking.trace.TraceSegmentRef;
@@ -35,6 +37,7 @@ public final class TracerContext {
      */
     TracerContext() {
         this.segment = new TraceSegment(Config.Agent.APPLICATION_CODE);
+        ServiceManager.INSTANCE.findService(SamplingService.class).trySampling(this.segment);
         this.spanIdGenerator = 0;
     }
 
@@ -126,6 +129,7 @@ public final class TracerContext {
         carrier.setApplicationCode(Config.Agent.APPLICATION_CODE);
         carrier.setPeerHost(Tags.PEER_HOST.get(activeSpan()));
         carrier.setDistributedTraceIds(this.segment.getRelatedGlobalTraces());
+        carrier.setSampled(this.segment.isSampled());
     }
 
     /**
@@ -137,6 +141,7 @@ public final class TracerContext {
     public void extract(ContextCarrier carrier) {
         if(carrier.isValid()) {
             this.segment.ref(getRef(carrier));
+            ServiceManager.INSTANCE.findService(SamplingService.class).setSampleWhenExtract(this.segment, carrier);
             this.segment.relatedGlobalTraces(carrier.getDistributedTraceIds());
         }
     }
diff --git a/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/queue/TraceSegmentProcessQueue.java b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/queue/TraceSegmentProcessQueue.java
index 9d25f94ff..94ceac768 100644
--- a/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/queue/TraceSegmentProcessQueue.java
+++ b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/queue/TraceSegmentProcessQueue.java
@@ -43,9 +43,14 @@ public class TraceSegmentProcessQueue extends StatusBootService implements Trace
         disruptor.start();
     }
 
+    /**
+     * Append the given traceSegment to the queue, wait for sending to Collector.
+     *
+     * @param traceSegment finished {@link TraceSegment}
+     */
     @Override
     public void afterFinished(TraceSegment traceSegment) {
-        if (isStarted()) {
+        if (isStarted() && traceSegment.isSampled()) {
             long sequence = this.buffer.next();  // Grab the next sequence
             try {
                 TraceSegmentHolder data = this.buffer.get(sequence);
diff --git a/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/sampling/IllegalSamplingRateException.java b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/sampling/IllegalSamplingRateException.java
new file mode 100644
index 000000000..bb89d7a86
--- /dev/null
+++ b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/sampling/IllegalSamplingRateException.java
@@ -0,0 +1,12 @@
+package com.a.eye.skywalking.api.sampling;
+
+/**
+ * Use <code>IllegalSamplingRateException</code>, only if the rate can not be supported.
+ *
+ * @author wusheng
+ */
+public class IllegalSamplingRateException extends Exception {
+    IllegalSamplingRateException(String message) {
+        super(message);
+    }
+}
diff --git a/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/sampling/SamplingService.java b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/sampling/SamplingService.java
new file mode 100644
index 000000000..6967c203d
--- /dev/null
+++ b/skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/api/sampling/SamplingService.java
@@ -0,0 +1,67 @@
+package com.a.eye.skywalking.api.sampling;
+
+import com.a.eye.skywalking.api.boot.BootService;
+import com.a.eye.skywalking.api.conf.Config;
+import com.a.eye.skywalking.api.context.ContextCarrier;
+import com.a.eye.skywalking.logging.ILog;
+import com.a.eye.skywalking.logging.LogManager;
+import com.a.eye.skywalking.trace.TraceSegment;
+
+/**
+ * The <code>SamplingService</code> take charge of how to sample the {@link TraceSegment}. Every {@link TraceSegment}s
+ * have been traced, but, considering CPU cost of serialization/deserialization, and network bandwidth, the agent do NOT
+ * send all of them to collector, if SAMPLING is on.
+ *
+ * By default, SAMPLING is off, and {@link Config.Agent#SAMPLING_RATE} == 1000.
+ *
+ * @author wusheng
+ */
+public class SamplingService implements BootService {
+    private static ILog logger = LogManager.getLogger(SamplingService.class);
+
+    private volatile boolean on = false;
+    private volatile int rate = 0;
+    private volatile int rollingSeed = 0;
+
+    @Override
+    public void bootUp() throws Throwable {
+        if (Config.Agent.SAMPLING_RATE == 10000) {
+            return;
+        }
+        if (Config.Agent.SAMPLING_RATE > 10000 || Config.Agent.SAMPLING_RATE < 1) {
+            throw new IllegalSamplingRateException("sampling rate should stay in (0, 10000].");
+        }
+        rate = 10000 / Config.Agent.SAMPLING_RATE;
+        on = true;
+
+        logger.debug("The trace sampling is on, and the sampling rate is: {}", rate);
+    }
+
+    public void trySampling(TraceSegment segment) {
+        if (on) {
+            if (rollingSeed++ != rate) {
+                segment.setSampled(false);
+            }
+        }
+    }
+
+    /**
+     * Set the {@link TraceSegment} to sampled, when {@link ContextCarrier} contains "isSampled" flag.
+     *
+     * A -> B, if TraceSegment is sampled in A, then the related TraceSegment in B must be sampled, no matter you
+     * sampling rate. And reset the {@link #rollingSeed}, in case of too many {@link TraceSegment}s, which started in
+     * this JVM, are sampled.
+     *
+     * @param segment the current TraceSegment.
+     * @param carrier
+     */
+    public void setSampleWhenExtract(TraceSegment segment, ContextCarrier carrier) {
+        if(on) {
+            if (!segment.isSampled() && carrier.isSampled()) {
+                segment.setSampled(true);
+                this.rollingSeed = 0;
+            }
+        }
+    }
+
+}
diff --git a/skywalking-sniffer/skywalking-api/src/main/resources/META-INF/services/com.a.eye.skywalking.api.boot.BootService b/skywalking-sniffer/skywalking-api/src/main/resources/META-INF/services/com.a.eye.skywalking.api.boot.BootService
index c84f7acac..0a0bbb211 100644
--- a/skywalking-sniffer/skywalking-api/src/main/resources/META-INF/services/com.a.eye.skywalking.api.boot.BootService
+++ b/skywalking-sniffer/skywalking-api/src/main/resources/META-INF/services/com.a.eye.skywalking.api.boot.BootService
@@ -1,3 +1,4 @@
 com.a.eye.skywalking.api.queue.TraceSegmentProcessQueue
 com.a.eye.skywalking.api.context.ContextManager
 com.a.eye.skywalking.api.client.CollectorClientService
+com.a.eye.skywalking.api.sampling.SamplingService
diff --git a/skywalking-sniffer/skywalking-api/src/test/java/com/a/eye/skywalking/api/context/ContextCarrierTestCase.java b/skywalking-sniffer/skywalking-api/src/test/java/com/a/eye/skywalking/api/context/ContextCarrierTestCase.java
index 269911b79..6809afed6 100644
--- a/skywalking-sniffer/skywalking-api/src/test/java/com/a/eye/skywalking/api/context/ContextCarrierTestCase.java
+++ b/skywalking-sniffer/skywalking-api/src/test/java/com/a/eye/skywalking/api/context/ContextCarrierTestCase.java
@@ -18,17 +18,18 @@ public class ContextCarrierTestCase {
         carrier.setSpanId(100);
         carrier.setApplicationCode("REMOTE_APP");
         carrier.setPeerHost("10.2.3.16:8080");
+        carrier.setSampled(true);
         List<DistributedTraceId> ids = new LinkedList<DistributedTraceId>();
         ids.add(new PropagatedTraceId("Trace.global.id.123"));
         carrier.setDistributedTraceIds(ids);
 
-        Assert.assertEquals("trace_id_A|100|REMOTE_APP|10.2.3.16:8080|Trace.global.id.123", carrier.serialize());
+        Assert.assertEquals("trace_id_A|100|REMOTE_APP|10.2.3.16:8080|Trace.global.id.123|1", carrier.serialize());
     }
 
     @Test
     public void testDeserialize(){
         ContextCarrier carrier = new ContextCarrier();
-        carrier.deserialize("trace_id_A|100|REMOTE_APP|10.2.3.16:8080|Trace.global.id.123,Trace.global.id.222");
+        carrier.deserialize("trace_id_A|100|REMOTE_APP|10.2.3.16:8080|Trace.global.id.123,Trace.global.id.222|1");
 
         Assert.assertEquals("trace_id_A", carrier.getTraceSegmentId());
         Assert.assertEquals(100, carrier.getSpanId());
@@ -36,6 +37,7 @@ public class ContextCarrierTestCase {
         Assert.assertEquals("10.2.3.16:8080", carrier.getPeerHost());
         Assert.assertEquals("Trace.global.id.123", carrier.getDistributedTraceIds().get(0).get());
         Assert.assertEquals("Trace.global.id.222", carrier.getDistributedTraceIds().get(1).get());
+        Assert.assertEquals(true, carrier.isSampled());
     }
 
     @Test
@@ -62,6 +64,10 @@ public class ContextCarrierTestCase {
 
         carrier = new ContextCarrier();
         carrier.deserialize("trace_id|100|REMOTE_APP|10.2.3.16:8080|Trace.global.id.123,Trace.global.id.222");
+        Assert.assertFalse(carrier.isValid());
+
+        carrier = new ContextCarrier();
+        carrier.deserialize("trace_id|100|REMOTE_APP|10.2.3.16:8080|Trace.global.id.123,Trace.global.id.222|0");
         Assert.assertTrue(carrier.isValid());
     }
 }
diff --git a/skywalking-sniffer/skywalking-sdk-plugin/dubbo-plugin/src/test/java/com/a/eye/skywalking/plugin/dubbo/DubboInterceptorTest.java b/skywalking-sniffer/skywalking-sdk-plugin/dubbo-plugin/src/test/java/com/a/eye/skywalking/plugin/dubbo/DubboInterceptorTest.java
index 9f03be8bf..75026a8dd 100644
--- a/skywalking-sniffer/skywalking-sdk-plugin/dubbo-plugin/src/test/java/com/a/eye/skywalking/plugin/dubbo/DubboInterceptorTest.java
+++ b/skywalking-sniffer/skywalking-sdk-plugin/dubbo-plugin/src/test/java/com/a/eye/skywalking/plugin/dubbo/DubboInterceptorTest.java
@@ -155,7 +155,7 @@ public class DubboInterceptorTest {
     @Test
     public void testProviderWithAttachment() {
         when(rpcContext.isConsumerSide()).thenReturn(false);
-        when(rpcContext.getAttachment(DubboInterceptor.ATTACHMENT_NAME_OF_CONTEXT_DATA)).thenReturn("302017.1487666919810.624424584.17332.1.1|1|REMOTE_APP|127.0.0.1|Trace.globalId.123");
+        when(rpcContext.getAttachment(DubboInterceptor.ATTACHMENT_NAME_OF_CONTEXT_DATA)).thenReturn("302017.1487666919810.624424584.17332.1.1|1|REMOTE_APP|127.0.0.1|Trace.globalId.123|1");
 
         dubboInterceptor.beforeMethod(classInstanceContext, methodInvokeContext, methodInterceptResult);
         dubboInterceptor.afterMethod(classInstanceContext, methodInvokeContext, result);
@@ -168,7 +168,7 @@ public class DubboInterceptorTest {
         when(rpcContext.isConsumerSide()).thenReturn(false);
         when(BugFixActive.isActive()).thenReturn(true);
 
-        testParam.setTraceContext("302017.1487666919810.624424584.17332.1.1|1|REMOTE_APP|127.0.0.1|Trace.globalId.123");
+        testParam.setTraceContext("302017.1487666919810.624424584.17332.1.1|1|REMOTE_APP|127.0.0.1|Trace.globalId.123|1");
 
 
         dubboInterceptor.beforeMethod(classInstanceContext, methodInvokeContext, methodInterceptResult);
diff --git a/skywalking-sniffer/skywalking-sdk-plugin/motan-plugin/src/test/java/com/a/eye/skywalking/plugin/motan/MotanProviderInterceptorTest.java b/skywalking-sniffer/skywalking-sdk-plugin/motan-plugin/src/test/java/com/a/eye/skywalking/plugin/motan/MotanProviderInterceptorTest.java
index 140bc34f4..e1a75e3a9 100644
--- a/skywalking-sniffer/skywalking-sdk-plugin/motan-plugin/src/test/java/com/a/eye/skywalking/plugin/motan/MotanProviderInterceptorTest.java
+++ b/skywalking-sniffer/skywalking-sdk-plugin/motan-plugin/src/test/java/com/a/eye/skywalking/plugin/motan/MotanProviderInterceptorTest.java
@@ -94,7 +94,7 @@ public class MotanProviderInterceptorTest {
     @Test
     public void testInvokerWithRefSegment() {
         HashMap attachments = new HashMap();
-        attachments.put("SWTraceContext", "302017.1487666919810.624424584.17332.1.1|1|REMOTE_APP|127.0.0.1|Trace.globalId.123");
+        attachments.put("SWTraceContext", "302017.1487666919810.624424584.17332.1.1|1|REMOTE_APP|127.0.0.1|Trace.globalId.123|1");
         when(request.getAttachments()).thenReturn(attachments);
 
         invokeInterceptor.beforeMethod(instanceContext, interceptorContext, null);
diff --git a/skywalking-sniffer/skywalking-sdk-plugin/tomcat-7.x-8.x-plugin/src/test/java/com/a/eye/skywalking/plugin/tomcat78x/TomcatInterceptorTest.java b/skywalking-sniffer/skywalking-sdk-plugin/tomcat-7.x-8.x-plugin/src/test/java/com/a/eye/skywalking/plugin/tomcat78x/TomcatInterceptorTest.java
index 6d2b4e38a..76f01259d 100644
--- a/skywalking-sniffer/skywalking-sdk-plugin/tomcat-7.x-8.x-plugin/src/test/java/com/a/eye/skywalking/plugin/tomcat78x/TomcatInterceptorTest.java
+++ b/skywalking-sniffer/skywalking-sdk-plugin/tomcat-7.x-8.x-plugin/src/test/java/com/a/eye/skywalking/plugin/tomcat78x/TomcatInterceptorTest.java
@@ -81,7 +81,7 @@ public class TomcatInterceptorTest {
 
     @Test
     public void testWithSerializedContextData() {
-        when(request.getHeader(TomcatInterceptor.HEADER_NAME_OF_CONTEXT_DATA)).thenReturn("302017.1487666919810.624424584.17332.1.1|1|REMOTE_APP|127.0.0.1|Trace.globalId.123");
+        when(request.getHeader(TomcatInterceptor.HEADER_NAME_OF_CONTEXT_DATA)).thenReturn("302017.1487666919810.624424584.17332.1.1|1|REMOTE_APP|127.0.0.1|Trace.globalId.123|1");
 
         tomcatInterceptor.beforeMethod(classInstanceContext, methodInvokeContext, methodInterceptResult);
         tomcatInterceptor.afterMethod(classInstanceContext, methodInvokeContext, null);
diff --git a/skywalking-sniffer/skywalking-toolkit-activation/skywalking-toolkit-opentracing-activation/src/main/java/com/a/eye/skywalking/toolkit/activation/opentracing/span/interceptor/SpanSetTagInterceptor.java b/skywalking-sniffer/skywalking-toolkit-activation/skywalking-toolkit-opentracing-activation/src/main/java/com/a/eye/skywalking/toolkit/activation/opentracing/span/interceptor/SpanSetTagInterceptor.java
index 028ea37c6..e3a6e7ba9 100644
--- a/skywalking-sniffer/skywalking-toolkit-activation/skywalking-toolkit-opentracing-activation/src/main/java/com/a/eye/skywalking/toolkit/activation/opentracing/span/interceptor/SpanSetTagInterceptor.java
+++ b/skywalking-sniffer/skywalking-toolkit-activation/skywalking-toolkit-opentracing-activation/src/main/java/com/a/eye/skywalking/toolkit/activation/opentracing/span/interceptor/SpanSetTagInterceptor.java
@@ -24,8 +24,10 @@ public class SpanSetTagInterceptor implements InstanceMethodsAroundInterceptor {
             ContextManager.activeSpan().setTag(key, (String)value);
         else if (value instanceof Boolean)
             ContextManager.activeSpan().setTag(key, (Boolean)value);
-        else if (value instanceof Number)
-            ContextManager.activeSpan().setTag(key, (Number)value);
+        else if (value instanceof Integer)
+            ContextManager.activeSpan().setTag(key, (Integer)value);
+        else
+            ContextManager.activeSpan().setTag(key, value.toString());
     }
 
     @Override