diff --git a/src/main/java/com/profiler/context/Annotation.java b/src/main/java/com/profiler/context/Annotation.java
new file mode 100644
index 000000000..64507bea4
--- /dev/null
+++ b/src/main/java/com/profiler/context/Annotation.java
@@ -0,0 +1,52 @@
+package com.profiler.context;
+
+public class Annotation {
+
+	protected final long timestamp;
+	protected final String value;
+	protected final EndPoint endPoint;
+
+	protected long processStart;
+	protected long processEnd;
+
+	/**
+	 * @param timestamp
+	 *            when was this annotation created? microseconds from epoch
+	 * @param value
+	 *            description of what happened at the timestamp could for
+	 *            example be "cache miss for key: x"
+	 * @param endPoint
+	 *            host this annotation was created on
+	 */
+	public Annotation(long timestamp, String value, EndPoint endPoint) {
+		this.timestamp = timestamp;
+		this.value = value;
+		this.endPoint = endPoint;
+	}
+
+	public long getTimestamp() {
+		return timestamp;
+	}
+
+	public void processStart() {
+		processStart = System.nanoTime();
+	}
+
+	public void processEnd() {
+		processEnd = System.nanoTime();
+	}
+
+	public String toString() {
+		StringBuilder sb = new StringBuilder();
+
+		sb.append("Annotation[");
+		sb.append("Timestamp=").append(timestamp);
+		sb.append("Value=").append(value);
+		sb.append("EndPoint=").append(endPoint);
+		sb.append("ProcessStart=").append(processStart);
+		sb.append("ProcessEnd=").append(processEnd);
+		sb.append("]");
+
+		return sb.toString();
+	}
+}
diff --git a/src/main/java/com/profiler/context/BinaryAnnotation.java b/src/main/java/com/profiler/context/BinaryAnnotation.java
new file mode 100644
index 000000000..20ee53397
--- /dev/null
+++ b/src/main/java/com/profiler/context/BinaryAnnotation.java
@@ -0,0 +1,19 @@
+package com.profiler.context;
+
+public class BinaryAnnotation extends Annotation {
+
+	protected final byte[] binaryValue;
+
+	/**
+	 * @param timestamp
+	 *            when was this annotation created? microseconds from epoch
+	 * @param value
+	 *            detailed description of what happened at the timestamp
+	 * @param host
+	 *            host this annotation was created on
+	 */
+	public BinaryAnnotation(long timestamp, byte[] value, EndPoint host) {
+		super(timestamp, null, host);
+		this.binaryValue = value;
+	}
+}
diff --git a/src/main/java/com/profiler/context/EndPoint.java b/src/main/java/com/profiler/context/EndPoint.java
new file mode 100644
index 000000000..818614f1c
--- /dev/null
+++ b/src/main/java/com/profiler/context/EndPoint.java
@@ -0,0 +1,22 @@
+package com.profiler.context;
+
+public class EndPoint {
+
+	public static final EndPoint NONE = null;
+
+	private final String protocol;
+	private final String ip;
+	private final int port;
+	private final String name;
+
+	public EndPoint(String protocol, String ip, int port, String name) {
+		this.protocol = protocol;
+		this.ip = ip;
+		this.port = port;
+		this.name = name;
+	}
+
+	public String toString() {
+		return "EndPoint[Protocol=" + protocol + ", IP=" + ip + ", Port=" + port + ", Name=" + name + "]";
+	}
+}
diff --git a/src/main/java/com/profiler/context/IDFactory.java b/src/main/java/com/profiler/context/IDFactory.java
new file mode 100644
index 000000000..f7e35f26f
--- /dev/null
+++ b/src/main/java/com/profiler/context/IDFactory.java
@@ -0,0 +1,11 @@
+package com.profiler.context;
+
+import java.util.UUID;
+
+public class IDFactory {
+
+	public static String newTraceID() {
+		UUID uuid = UUID.randomUUID();
+		return uuid.toString();
+	}
+}
diff --git a/src/main/java/com/profiler/context/RequestContext.java b/src/main/java/com/profiler/context/RequestContext.java
new file mode 100644
index 000000000..128c22821
--- /dev/null
+++ b/src/main/java/com/profiler/context/RequestContext.java
@@ -0,0 +1,24 @@
+package com.profiler.context;
+
+import com.profiler.util.NamedThreadLocal;
+
+public class RequestContext {
+
+	private static final ThreadLocal<Span> span = new NamedThreadLocal<Span>("Span");
+
+	public static Span getSpan(String traceID, int parentSpanID, String name, boolean debug) {
+		Span ctx = span.get();
+		if (ctx == null) {
+			ctx = new Span(traceID, parentSpanID, name, debug);
+			span.set(ctx);
+		}
+		return ctx;
+	}
+
+	/**
+	 * Calling from Span.flush()
+	 */
+	public static void removeCurrentContext() {
+		span.remove();
+	}
+}
diff --git a/src/main/java/com/profiler/context/Span.java b/src/main/java/com/profiler/context/Span.java
new file mode 100644
index 000000000..67c6248a3
--- /dev/null
+++ b/src/main/java/com/profiler/context/Span.java
@@ -0,0 +1,79 @@
+package com.profiler.context;
+
+import java.util.Comparator;
+import java.util.SortedSet;
+import java.util.TreeSet;
+
+/**
+ * A span represents one RPC request. A trace is made up of many spans.
+ * 
+ * @author netspider
+ * 
+ */
+public class Span {
+
+	private final String traceID;
+	private final int spanID;
+	private final int parentSpanID;
+	private final String name;
+	private final long createTime;
+	private final boolean debug;
+
+	private final SortedSet<Annotation> annotations = new TreeSet<Annotation>(new Comparator<Annotation>() {
+		@Override
+		public int compare(Annotation a1, Annotation a2) {
+			return (int) (a1.getTimestamp() - a2.getTimestamp());
+		}
+	});
+
+	public Span(String traceID, int parentSpanID, String name, boolean debug) {
+		if (traceID == null) {
+			this.traceID = traceID;
+		} else {
+			this.traceID = IDFactory.newTraceID();
+		}
+
+		if (parentSpanID < 0) {
+			this.spanID = 1;
+		} else {
+			this.spanID = ++parentSpanID;
+		}
+
+		this.parentSpanID = parentSpanID;
+		this.name = name;
+		this.createTime = System.nanoTime();
+		this.debug = debug;
+	}
+
+	public boolean addAnnotation(Annotation annotation) {
+		return annotations.add(annotation);
+	}
+
+	private void flush() {
+		System.out.println("TODO: flush collected data.");
+		RequestContext.removeCurrentContext();
+	}
+
+	public String getTraceID() {
+		return traceID;
+	}
+
+	public int getNextSpanID() {
+		return spanID + 1;
+	}
+
+	public String toString() {
+		StringBuilder sb = new StringBuilder();
+
+		sb.append("Span[");
+		sb.append("TraceID=").append(traceID);
+		sb.append(", SpanID=").append(spanID);
+		sb.append(", ParentSpanID=").append(parentSpanID);
+		sb.append(", CreateTime=").append(createTime);
+		sb.append(", Name=").append(name);
+		sb.append(", Annotations=").append(annotations);
+		sb.append("]");
+
+		return sb.toString();
+	}
+}