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
new file mode 100644
index 0000000000000000000000000000000000000000..47c4b7d182bf3719848cd33a78ed9b1b8578d111
--- /dev/null
+++ b/skywalking-commons/skywalking-trace/src/main/java/com/a/eye/skywalking/trace/LogData.java
@@ -0,0 +1,18 @@
+package com.a.eye.skywalking.trace;
+
+import java.util.Map;
+
+/**
+ * It is a holder of one log record.
+ *
+ * Created by wusheng on 2017/2/17.
+ */
+public class LogData {
+    private final long time;
+    private final Map<String, ?> fields;
+
+    LogData(long time, Map<String, ?> fields) {
+        this.time = time;
+        this.fields = 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 4b7fcac2e01f6012c9b9389556a154ba2ddba220..2c81181c30a6ecea6b5b937e297fcd2c872b1eaa 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
@@ -1,5 +1,11 @@
 package com.a.eye.skywalking.trace;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
 /**
  * Span is a concept from OpenTracing Spec, also from Google Dapper Paper.
  * Traces in OpenTracing are defined implicitly by their Spans.
@@ -21,4 +27,151 @@ package com.a.eye.skywalking.trace;
  * Created by wusheng on 2017/2/17.
  */
 public class Span {
+    private int spanId;
+
+    private int parentSpanId;
+
+    /**
+     * The start time of this Span.
+     */
+    private long startTime;
+
+    /**
+     * The end time of this Span.
+     */
+    private long endTime;
+
+    /**
+     * The operation name ot this Span.
+     * If you want to know, how to set an operation name,
+     * {@see https://github.com/opentracing/specification/blob/master/specification.md#start-a-new-span}
+     */
+    private String operationName;
+
+    /**
+     * Tag is a concept from OpenTracing spec.
+     *
+     * {@see https://github.com/opentracing/specification/blob/master/specification.md#set-a-span-tag}
+     */
+    private final Map<String,Object> tags = new HashMap<String,Object>();
+
+    /**
+     * Log is a concept from OpenTracing spec.
+     *
+     * {@see https://github.com/opentracing/specification/blob/master/specification.md#log-structured-data}
+     */
+    private final List<LogData> logs = new ArrayList<LogData>();
+
+    /**
+     * Create a new span, by given span id and parent span id.
+     * This span must belong a {@link TraceSegment}, also is a part of Distributed Trace.
+     *
+     * @param spanId given by the creator, and must be unique id in the {@link TraceSegment}
+     * @param parentSpanId given by the creator, and must be an existed span id in the {@link TraceSegment}.
+     *                  Value -1 means no parent span if this {@link TraceSegment}.
+     * @param operationName {@link #operationName}
+     */
+    public Span(int spanId, int parentSpanId, String operationName){
+        this.spanId = spanId;
+        this.parentSpanId = parentSpanId;
+        this.startTime = System.currentTimeMillis();
+    }
+
+    /**
+     * Create a new span, by given span id and no parent span id.
+     * No parent span id means that, this Span is the first span of the {@link TraceSegment}
+     *
+     * @param spanId given by the creator, and must be unique id in the {@link TraceSegment}
+     * @param operationName {@link #operationName}
+     */
+    public Span(int spanId, String operationName){
+        this(spanId, -1, operationName);
+    }
+
+    /**
+     * Finish the active Span.
+     * When it is finished, it will be archived by the given {@link TraceSegment}, which owners it.
+     *
+     * @param owner of the Span.
+     */
+    public void finish(TraceSegment owner){
+        this.endTime = System.currentTimeMillis();
+        owner.archive(this);
+    }
+
+    /**
+     * Set a key:value tag on the Span.
+     */
+    public final Span setTag(String key, String value) {
+        tags.put(key, value);
+        return this;
+    }
+
+    public final Span setTag(String key, boolean value) {
+        tags.put(key, value);
+        return this;
+    }
+
+    public final Span setTag(String key, Number value) {
+        tags.put(key, value);
+        return this;
+    }
+
+    /**
+     * Get all tags from this span, but readonly.
+     *
+     * @return
+     */
+    public final Map<String,Object> getTags() {
+        return Collections.unmodifiableMap(tags);
+    }
+
+    /**
+     * This method is from opentracing-java.
+     * {@see https://github.com/opentracing/opentracing-java/blob/release-0.20.9/opentracing-api/src/main/java/io/opentracing/Span.java#L91}
+     *
+     * Log key:value pairs to the Span with the current walltime timestamp.
+     *
+     * <p><strong>CAUTIONARY NOTE:</strong> not all Tracer implementations support key:value log fields end-to-end.
+     * Caveat emptor.
+     *
+     * <p>A contrived example (using Guava, which is not required):
+     * <pre>{@code
+        span.log(
+            ImmutableMap.Builder<String, Object>()
+            .put("event", "soft error")
+            .put("type", "cache timeout")
+            .put("waited.millis", 1500)
+            .build());
+        }</pre>
+     *
+     * @param fields key:value log fields. Tracer implementations should support String, numeric, and boolean values;
+     *               some may also support arbitrary Objects.
+     * @return the Span, for chaining
+     * @see Span#log(String)
+     */
+    Span log(Map<String, ?> fields){
+        logs.add(new LogData(System.currentTimeMillis(), fields));
+        return this;
+    }
+
+    /**
+     * This method is from opentracing-java.
+     * {@see https://github.com/opentracing/opentracing-java/blob/release-0.20.9/opentracing-api/src/main/java/io/opentracing/Span.java#L120}
+     *
+     * Record an event at the current walltime timestamp.
+     *
+     * Shorthand for
+     *
+     * <pre>{@code
+        span.log(Collections.singletonMap("event", event));
+        }</pre>
+     *
+     * @param event the event value; often a stable identifier for a moment in the Span lifecycle
+     * @return the Span, for chaining
+     */
+    Span log(String event){
+        log(Collections.singletonMap("event", event));
+        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 bb671bfb16f7e06a362ad65cc9b95b90489ad921..7d164f2a904b83e93a8a45b2eebfb61c6432fd55 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
@@ -52,17 +52,18 @@ public class TraceSegment {
 
     /**
      * Create a trace segment, by given segmentId.
-     * This segmentId is generated by TraceSegmentRef, AKA tracer/agent module.
+     * This segmentId is generated by TraceSegmentRef, AKA, from tracer/agent module.
      *
      * @param segmentId {@link #traceSegmentId}
      */
     public TraceSegment(String segmentId) {
         this.traceSegmentId = segmentId;
         this.startTime = System.currentTimeMillis();
+        this.spans = new LinkedList<Span>();
     }
 
     /**
-     * Establish the link between this segment to his parents.
+     * Establish the link between this segment and its parents.
      * The first time, you {@link #ref(TraceSegmentRef)} to parent, it is affirmed as {@link #primaryRef}.
      * And others are affirmed as {@link #refs}.
      *
@@ -78,4 +79,21 @@ public class TraceSegment {
             refs.add(refSegment);
         }
     }
+
+    /**
+     * After {@link Span} is finished, as be controller by "skywalking-api" module,
+     * notify the {@link TraceSegment} to archive it.
+     *
+     * @param finishedSpan
+     */
+    void archive(Span finishedSpan){
+        spans.add(finishedSpan);
+    }
+
+    /**
+     * Finish this {@link TraceSegment}.
+     */
+    public void finish(){
+       this.endTime = System.currentTimeMillis();
+    }
 }