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 47c4b7d18..250bc2516 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
@@ -15,4 +15,12 @@ public class LogData {
         this.time = time;
         this.fields = fields;
     }
+
+    public long getTime() {
+        return time;
+    }
+
+    public Map<String, ?> getFields() {
+        return fields;
+    }
 }
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 35018c9fb..8db7f1e6f 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
@@ -202,4 +202,24 @@ public class Span {
     public int getSpanId() {
         return spanId;
     }
+
+    public int getParentSpanId() {
+        return parentSpanId;
+    }
+
+    public long getStartTime() {
+        return startTime;
+    }
+
+    public long getEndTime() {
+        return endTime;
+    }
+
+    public String getOperationName() {
+        return operationName;
+    }
+
+    public List<LogData> getLogs() {
+        return Collections.unmodifiableList(logs);
+    }
 }
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 428cd760f..9ffeea26e 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
@@ -22,10 +22,6 @@ public abstract class AbstractTag<T> {
         this.key = tagKey;
     }
 
-    public String getKey() {
-        return key;
-    }
-
     protected abstract void set(Span span, T tagValue);
 
     public abstract T get(Span span);
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 62004a7f0..229521287 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
@@ -14,7 +14,7 @@ public class StringTag extends AbstractTag<String> {
     }
 
     @Override
-    protected void set(Span span, String tagValue) {
+    public void set(Span span, String tagValue) {
         span.setTag(key, tagValue);
     }
 
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
new file mode 100644
index 000000000..316c278ac
--- /dev/null
+++ b/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/LogDataTestCase.java
@@ -0,0 +1,20 @@
+package com.a.eye.skywalking.trace;
+
+import java.util.HashMap;
+import java.util.Map;
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Created by wusheng on 2017/2/18.
+ */
+public class LogDataTestCase {
+    @Test
+    public void testHoldValue(){
+        Map<String, ?> fields = new HashMap<String, String>();
+        LogData logData = new LogData(123L, fields);
+
+        Assert.assertEquals(123, logData.getTime());
+        Assert.assertEquals(fields, logData.getFields());
+    }
+}
diff --git a/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/SpanTestCase.java b/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/SpanTestCase.java
new file mode 100644
index 000000000..d57cf2d22
--- /dev/null
+++ b/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/SpanTestCase.java
@@ -0,0 +1,85 @@
+package com.a.eye.skywalking.trace;
+
+import com.a.eye.skywalking.trace.tag.Tags;
+import java.util.Collections;
+import java.util.Map;
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Created by wusheng on 2017/2/18.
+ */
+public class SpanTestCase {
+    @Test
+    public void testConstructors() {
+        Span span1 = new Span(0, "serviceA");
+        Span span2 = new Span(2, span1, "serviceA");
+
+        Assert.assertEquals(-1, span1.getParentSpanId());
+        Assert.assertEquals(0, span2.getParentSpanId());
+        Assert.assertTrue(span1.getStartTime() > 0);
+        Assert.assertTrue(span2.getStartTime() > 0);
+    }
+
+    @Test
+    public void testFinish() {
+        TraceSegment owner = new TraceSegment("trace_1");
+
+        Span span1 = new Span(0, "serviceA");
+
+        Assert.assertTrue(span1.getEndTime() == 0);
+
+        span1.finish(owner);
+        Assert.assertEquals(span1, owner.getSpans().get(0));
+        Assert.assertTrue(span1.getEndTime() > 0);
+    }
+
+    @Test
+    public void testSetTag() {
+        Span span1 = new Span(0, "serviceA");
+        Tags.SPAN_KIND.set(span1, "client");
+        Tags.COMPONENT.set(span1, "Spring");
+        Tags.PEER_HOST_IPV4.set(span1, ipToInt("127.0.0.1"));
+        Tags.ERROR.set(span1, true);
+        Tags.HTTP_STATUS.set(span1, 302);
+        Tags.HTTP_URL.set(span1, "http://127.0.0.1/serviceA");
+        Tags.DB_URL.set(span1, "jdbc:127.0.0.1:user");
+        Tags.DB_SQL.set(span1, "select * from users");
+
+        Map<String, Object> tags = span1.getTags();
+        Assert.assertEquals(8, tags.size());
+        Assert.assertEquals("client", Tags.SPAN_KIND.get(span1));
+        Assert.assertEquals("127.0.0.1", intToIp(Tags.PEER_HOST_IPV4.get(span1)));
+        Assert.assertTrue(Tags.ERROR.get(span1));
+    }
+
+    private int ipToInt(String ipAddress) {
+        int result = 0;
+        String[] ipAddressInArray = ipAddress.split("\\.");
+
+        for (int i = 3; i >= 0; i--) {
+
+            int ip = Integer.parseInt(ipAddressInArray[3 - i]);
+
+            //left shifting 24,16,8,0 and bitwise OR
+            //1. 192 << 24
+            //1. 168 << 16
+            //1. 1   << 8
+            //1. 2   << 0
+            result |= ip << (i * 8);
+        }
+        return result;
+    }
+
+    private static String intToIp(int longIp) {
+        StringBuffer sb = new StringBuffer("");
+        sb.append(String.valueOf((longIp >>> 24)));
+        sb.append(".");
+        sb.append(String.valueOf((longIp & 0x00FFFFFF) >>> 16));
+        sb.append(".");
+        sb.append(String.valueOf((longIp & 0x0000FFFF) >>> 8));
+        sb.append(".");
+        sb.append(String.valueOf((longIp & 0x000000FF)));
+        return sb.toString();
+    }
+}
diff --git a/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/TraceSegmentTestCase.java b/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/TraceSegmentTestCase.java
index e6b253de0..401c9f380 100644
--- a/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/TraceSegmentTestCase.java
+++ b/skywalking-commons/skywalking-trace/src/test/java/com/a/eye/skywalking/trace/TraceSegmentTestCase.java
@@ -37,6 +37,9 @@ public class TraceSegmentTestCase {
         Assert.assertEquals(ref1, segment.getPrimaryRef());
         Assert.assertEquals(ref2, segment.getRefs().get(0));
         Assert.assertEquals(ref3, segment.getRefs().get(1));
+
+        Assert.assertEquals("parent_trace_0", segment.getPrimaryRef().getTraceSegmentId());
+        Assert.assertEquals(1, segment.getPrimaryRef().getSpanId());
     }
 
     @Test