Refactor MeasurementDescriptor. (#396)

* Refactor MeasurementDescriptor.

* Remove Measure.Name class for now.

16 files changed, 439 insertions, 542 deletions

diff --git a/core/src/main/java/io/opencensus/stats/Measure.java b/core/src/main/java/io/opencensus/stats/Measure.java
new file mode 100644
index 00000000..3f637c95
--- /dev/null
+++ b/core/src/main/java/io/opencensus/stats/Measure.java
@@ -0,0 +1,119 @@
+/*
+ * Copyright 2016, Google Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.opencensus.stats;
+
+import com.google.auto.value.AutoValue;
+import io.opencensus.common.Function;
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * Measure.
+ */
+@Immutable
+public abstract class Measure {
+
+  /**
+   * Applies the given match function to the underlying data type.
+   */
+  public abstract <T> T match(Function<DoubleMeasure, T> p0, Function<LongMeasure, T> p1);
+
+  /**
+   * Name of measure, as a {@code String}.
+   */
+  public abstract String getName();
+
+  /**
+   * Detailed description of the measure, used in documentation.
+   */
+  public abstract String getDescription();
+
+  /**
+   * The units in which {@link Measure} values are measured.
+   *
+   * <p>The grammar for a unit is as follows:
+   *     Expression = Component { "." Component } { "/" Component } ;
+   *     Component = [ PREFIX ] UNIT [ Annotation ] | Annotation | "1" ;
+   *     Annotation = "{" NAME "}" ;
+   * For example, string “MBy{transmitted}/ms” stands for megabytes per milliseconds, and the
+   * annotation transmitted inside {} is just a comment of the unit.
+   */
+  public abstract String getUnit();
+
+  // Prevents this class from being subclassed anywhere else.
+  private Measure() {
+  }
+
+  @Immutable
+  @AutoValue
+  public abstract static class DoubleMeasure extends Measure {
+
+    DoubleMeasure() {
+    }
+
+    /**
+     * Constructs a new {@link DoubleMeasure}.
+     */
+    public static DoubleMeasure create(String name, String description, String unit) {
+      // TODO(dpo): ensure that measure names are unique, and consider if there should be any
+      // restricitons on name (e.g. size, characters).
+      return new AutoValue_Measure_DoubleMeasure(name, description, unit);
+    }
+
+    @Override
+    public <T> T match(Function<DoubleMeasure, T> p0, Function<LongMeasure, T> p1) {
+      return p0.apply(this);
+    }
+
+    @Override
+    public abstract String getName();
+
+    @Override
+    public abstract String getDescription();
+
+    @Override
+    public abstract String getUnit();
+  }
+
+  @Immutable
+  @AutoValue
+  // TODO: determine whether we want to support LongMeasure in V0.1
+  public abstract static class LongMeasure extends Measure {
+
+    LongMeasure() {
+    }
+
+    /**
+     * Constructs a new {@link LongMeasure}.
+     */
+    public static LongMeasure create(String name, String description, String unit) {
+      // TODO(dpo): ensure that measure names are unique, and consider if there should be any
+      // restricitons on name (e.g. size, characters).
+      return new AutoValue_Measure_LongMeasure(name, description, unit);
+    }
+
+    @Override
+    public <T> T match(Function<DoubleMeasure, T> p0, Function<LongMeasure, T> p1) {
+      return p1.apply(this);
+    }
+
+    @Override
+    public abstract String getName();
+
+    @Override
+    public abstract String getDescription();
+
+    @Override
+    public abstract String getUnit();
+  }
+}
diff --git a/core/src/main/java/io/opencensus/stats/MeasurementDescriptor.java b/core/src/main/java/io/opencensus/stats/MeasurementDescriptor.java
deleted file mode 100644
index 99668697..00000000
--- a/core/src/main/java/io/opencensus/stats/MeasurementDescriptor.java
+++ /dev/null
@@ -1,188 +0,0 @@
-/*
- * Copyright 2016, Google Inc.
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *     http://www.apache.org/licenses/LICENSE-2.0
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.opencensus.stats;
-
-import com.google.auto.value.AutoValue;
-import io.opencensus.internal.StringUtil;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import javax.annotation.concurrent.Immutable;
-
-/**
- * MeasurementDescriptor.
- *
- * <p>Note: MeasurementDescriptor names are {@link String}s with enforced restrictions.
- */
-@Immutable
-@AutoValue
-public abstract class MeasurementDescriptor {
-  public static final int MAX_LENGTH = StringUtil.MAX_LENGTH;
-
-  MeasurementDescriptor() {}
-
-  /**
-   * Constructs a new {@link MeasurementDescriptor}.
-   */
-  public static MeasurementDescriptor create(
-      String name, String description, MeasurementUnit unit) {
-    return create(Name.create(name), description, unit);
-  }
-
-  /**
-   * Constructs a new {@link MeasurementDescriptor}.
-   */
-  public static MeasurementDescriptor create(
-      Name name, String description, MeasurementUnit unit) {
-    return new AutoValue_MeasurementDescriptor(name, description, unit);
-  }
-
-  /**
-   * Name of measurement, e.g. rpc_latency, cpu. Must be unique.
-   */
-  public abstract MeasurementDescriptor.Name getMeasurementDescriptorName();
-
-  /**
-   * Name of measurement, as a {@code String}.
-   */
-  public final String getName() {
-    return getMeasurementDescriptorName().asString();
-  }
-
-  /**
-   * Detailed description of the measurement, used in documentation.
-   */
-  public abstract String getDescription();
-
-  /**
-   * The units in which {@link MeasurementDescriptor} values are measured.
-   */
-  public abstract MeasurementUnit getUnit();
-
-  /**
-   * Fundamental units of measurement.
-   */
-  public enum BasicUnit {
-    SCALAR,
-    BITS,
-    BYTES,
-    SECONDS,
-    CORES;
-  }
-
-  /**
-   * The name of a {@code MeasurementDescriptor}.
-   */
-  // This type should be used as the key when associating data with MeasurementDescriptors.
-  @Immutable
-  @AutoValue
-  public abstract static class Name {
-
-    Name() {}
-
-    /**
-     * Returns the name as a {@code String}.
-     *
-     * @return the name as a {@code String}.
-     */
-    public abstract String asString();
-
-    /**
-     * Creates a {@code MeasurementDescriptor.Name} from a {@code String}.
-     *
-     * @param name the name {@code String}.
-     * @return a {@code MeasurementDescriptor.Name} with the given name {@code String}.
-     */
-    public static Name create(String name) {
-      return new AutoValue_MeasurementDescriptor_Name(StringUtil.sanitize(name));
-    }
-  }
-
-  /**
-   * MeasurementUnit lets you build compound units of the form
-   * 10^n * (A * B * ...) / (X * Y * ...),
-   * where the elements in the numerator and denominator are all BasicUnits.  A
-   * MeasurementUnit must have at least one BasicUnit in its numerator.
-   *
-   * <p>To specify multiplication in the numerator or denominator, simply specify
-   * multiple numerator or denominator fields.  For example:
-   *
-   * <p>- byte-seconds (i.e. bytes * seconds):
-   *     numerator: BYTES
-   *     numerator: SECS
-   *
-   * <p>- events/sec^2 (i.e. rate of change of events/sec):
-   *     numerator: SCALAR
-   *     denominator: SECS
-   *     denominator: SECS
-   *
-   * <p>To specify multiples (in power of 10) of units, specify a non-zero power10
-   * value, for example:
-   *
-   * <p>- MB/s (i.e. megabytes / s):
-   *     power10: 6
-   *     numerator: BYTES
-   *     denominator: SECS
-   *
-   * <p>- nanoseconds
-   *     power10: -9
-   *     numerator: SECS
-   */
-  @Immutable
-  @AutoValue
-  public abstract static class MeasurementUnit {
-
-    MeasurementUnit() {}
-
-    /**
-     * Constructs a {@link MeasurementUnit}.
-     */
-    public static MeasurementUnit create(
-        int power10, List<BasicUnit> numerators, List<BasicUnit> denominators) {
-      return new AutoValue_MeasurementDescriptor_MeasurementUnit(
-          power10,
-          Collections.unmodifiableList(new ArrayList<BasicUnit>(numerators)),
-          Collections.unmodifiableList(new ArrayList<BasicUnit>(denominators)));
-    }
-
-    /**
-     * Constructs a {@link MeasurementUnit} without the optional {@code denominators}.
-     */
-    public static MeasurementUnit create(int power10, List<BasicUnit> numerators) {
-      return new AutoValue_MeasurementDescriptor_MeasurementUnit(
-          power10, numerators, Collections.<BasicUnit>emptyList());
-    }
-
-    /**
-     * Unit multiplier (i.e. 10^power10).
-     */
-    public abstract int getPower10();
-
-    /**
-     * Unit Numerators.
-     *
-     * <p>Note: The returned list is unmodifiable and attempts to update it will throw an
-     * UnsupportedOperationException.
-     */
-    public abstract List<BasicUnit> getNumerators();
-
-    /**
-     * Unit Denominators.
-     *
-     * <p>Note: The returned list is unmodifiable and attempts to update it will throw an
-     * UnsupportedOperationException.
-     */
-    public abstract List<BasicUnit> getDenominators();
-  }
-}
diff --git a/core/src/main/java/io/opencensus/stats/MeasurementMap.java b/core/src/main/java/io/opencensus/stats/MeasurementMap.java
index a961bf17..6694a933 100644
--- a/core/src/main/java/io/opencensus/stats/MeasurementMap.java
+++ b/core/src/main/java/io/opencensus/stats/MeasurementMap.java
@@ -18,34 +18,34 @@ import java.util.Iterator;
 import java.util.NoSuchElementException;
 
 /**
- * A map from {@link MeasurementDescriptor}'s to measured values.
+ * A map from {@link Measure}'s to measured values.
  */
 public final class MeasurementMap implements Iterable<MeasurementValue> {
   /**
-   * Constructs a {@link MeasurementMap} from the given {@link MeasurementDescriptor}
+   * Constructs a {@link MeasurementMap} from the given {@link Measure}
    * and associated value.
    */
-  public static MeasurementMap of(MeasurementDescriptor measurement, double value) {
-    return builder().put(measurement, value).build();
+  public static MeasurementMap of(Measure measure, double value) {
+    return builder().put(measure, value).build();
   }
 
   /**
-   * Constructs a {@link MeasurementMap} from the given {@link MeasurementDescriptor}'s
+   * Constructs a {@link MeasurementMap} from the given {@link Measure}'s
    * and associated values.
    */
-  public static MeasurementMap of(MeasurementDescriptor measurement1, double value1,
-      MeasurementDescriptor measurement2, double value2) {
-    return builder().put(measurement1, value1).put(measurement2, value2).build();
+  public static MeasurementMap of(Measure measure1, double value1,
+      Measure measure2, double value2) {
+    return builder().put(measure1, value1).put(measure2, value2).build();
   }
 
   /**
-   * Constructs a {@link MeasurementMap} from the given {@link MeasurementDescriptor}'s
+   * Constructs a {@link MeasurementMap} from the given {@link Measure}'s
    * and associated values.
    */
-  public static MeasurementMap of(MeasurementDescriptor measurement1, double value1,
-      MeasurementDescriptor measurement2, double value2,
-      MeasurementDescriptor measurement3, double value3) {
-    return builder().put(measurement1, value1).put(measurement2, value2).put(measurement3, value3)
+  public static MeasurementMap of(Measure measure1, double value1,
+      Measure measure2, double value2,
+      Measure measure3, double value3) {
+    return builder().put(measure1, value1).put(measure2, value2).put(measure3, value3)
         .build();
   }
 
@@ -57,14 +57,14 @@ public final class MeasurementMap implements Iterable<MeasurementValue> {
   }
 
   /**
-   * Returns the number of measurements in this {@link MeasurementMap}.
+   * Returns the number of measures in this {@link MeasurementMap}.
    */
   public int size() {
-    return measurements.size();
+    return measures.size();
   }
 
   /**
-   * Returns an {@link Iterator} over the measurement/value mappings in this {@link MeasurementMap}.
+   * Returns an {@link Iterator} over the measure/value mappings in this {@link MeasurementMap}.
    * The {@code Iterator} does not support {@link Iterator#remove()}.
    */
   @Override
@@ -72,10 +72,10 @@ public final class MeasurementMap implements Iterable<MeasurementValue> {
     return new MeasurementMapIterator();
   }
 
-  private final ArrayList<MeasurementValue> measurements;
+  private final ArrayList<MeasurementValue> measures;
 
-  private MeasurementMap(ArrayList<MeasurementValue> measurements) {
-    this.measurements = measurements;
+  private MeasurementMap(ArrayList<MeasurementValue> measures) {
+    this.measures = measures;
   }
 
   /**
@@ -83,45 +83,45 @@ public final class MeasurementMap implements Iterable<MeasurementValue> {
    */
   public static class Builder {
     /**
-     * Associates the {@link MeasurementDescriptor} with the given value. Subsequent updates to the
-     * same {@link MeasurementDescriptor} are ignored.
+     * Associates the {@link Measure} with the given value. Subsequent updates to the
+     * same {@link Measure} are ignored.
      *
-     * @param measurement the {@link MeasurementDescriptor}
-     * @param value the value to be associated with {@code measurement}
+     * @param measure the {@link Measure}
+     * @param value the value to be associated with {@code measure}
      * @return this
      */
-    public Builder put(MeasurementDescriptor measurement, double value) {
-      measurements.add(MeasurementValue.create(measurement, value));
+    public Builder put(Measure measure, double value) {
+      measures.add(MeasurementValue.create(measure, value));
       return this;
     }
 
     /**
-     * Constructs a {@link MeasurementMap} from the current measurements.
+     * Constructs a {@link MeasurementMap} from the current measures.
      */
     public MeasurementMap build() {
-      // Note: this makes adding measurements quadratic but is fastest for the sizes of
+      // Note: this makes adding measures quadratic but is fastest for the sizes of
       // MeasurementMaps that we should see. We may want to go to a strategy of sort/eliminate
       // for larger MeasurementMaps.
-      for (int i = 0; i < measurements.size(); i++) {
-        MeasurementDescriptor.Name current =
-            measurements.get(i).getMeasurement().getMeasurementDescriptorName();
-        for (int j = i + 1; j < measurements.size(); j++) {
-          if (current.equals(measurements.get(j).getMeasurement().getMeasurementDescriptorName())) {
-            measurements.remove(j);
+      for (int i = 0; i < measures.size(); i++) {
+        String current =
+            measures.get(i).getMeasurement().getName();
+        for (int j = i + 1; j < measures.size(); j++) {
+          if (current.equals(measures.get(j).getMeasurement().getName())) {
+            measures.remove(j);
             j--;
           }
         }
       }
-      return new MeasurementMap(measurements);
+      return new MeasurementMap(measures);
     }
 
-    private final ArrayList<MeasurementValue> measurements = new ArrayList<MeasurementValue>();
+    private final ArrayList<MeasurementValue> measures = new ArrayList<MeasurementValue>();
 
     private Builder() {
     }
   }
 
-  // Provides an unmodifiable Iterator over this instance's measurements.
+  // Provides an unmodifiable Iterator over this instance's measures.
   private final class MeasurementMapIterator implements Iterator<MeasurementValue> {
     @Override
     public boolean hasNext() {
@@ -130,10 +130,10 @@ public final class MeasurementMap implements Iterable<MeasurementValue> {
 
     @Override
     public MeasurementValue next() {
-      if (position >= measurements.size()) {
+      if (position >= measures.size()) {
         throw new NoSuchElementException();
       }
-      return measurements.get(position++);
+      return measures.get(position++);
     }
 
     @Override
@@ -141,7 +141,7 @@ public final class MeasurementMap implements Iterable<MeasurementValue> {
       throw new UnsupportedOperationException();
     }
 
-    private final int length = measurements.size();
+    private final int length = measures.size();
     private int position = 0;
   }
 }
diff --git a/core/src/main/java/io/opencensus/stats/MeasurementValue.java b/core/src/main/java/io/opencensus/stats/MeasurementValue.java
index 6c9cc3a6..efee6f39 100644
--- a/core/src/main/java/io/opencensus/stats/MeasurementValue.java
+++ b/core/src/main/java/io/opencensus/stats/MeasurementValue.java
@@ -21,14 +21,14 @@ public class MeasurementValue {
   /**
    * Constructs a measured value.
    */
-  public static MeasurementValue create(MeasurementDescriptor name, double value) {
+  public static MeasurementValue create(Measure name, double value) {
     return new MeasurementValue(name, value);
   }
 
   /**
-   * Extracts the measured {@link MeasurementDescriptor}.
+   * Extracts the measured {@link Measure}.
    */
-  public MeasurementDescriptor getMeasurement() {
+  public Measure getMeasurement() {
     return name;
   }
 
@@ -39,10 +39,10 @@ public class MeasurementValue {
     return value;
   }
 
-  private final MeasurementDescriptor name;
+  private final Measure name;
   private final double value;
 
-  private MeasurementValue(MeasurementDescriptor name, double value) {
+  private MeasurementValue(Measure name, double value) {
     this.name = name;
     this.value = value;
   }
diff --git a/core/src/main/java/io/opencensus/stats/RpcMeasurementConstants.java b/core/src/main/java/io/opencensus/stats/RpcMeasurementConstants.java
index c015e17c..415529a1 100644
--- a/core/src/main/java/io/opencensus/stats/RpcMeasurementConstants.java
+++ b/core/src/main/java/io/opencensus/stats/RpcMeasurementConstants.java
@@ -13,14 +13,10 @@
 
 package io.opencensus.stats;
 
-import io.opencensus.stats.MeasurementDescriptor.BasicUnit;
-import io.opencensus.stats.MeasurementDescriptor.MeasurementUnit;
-import java.util.Arrays;
-import java.util.List;
-
 /**
  * Constants for collecting rpc stats.
  */
+// TODO(songya): change *_COUNT constants to LongMeasure if it's supported in v0.1.
 public final class RpcMeasurementConstants {
 
   // Rpc tag keys.
@@ -28,125 +24,125 @@ public final class RpcMeasurementConstants {
   public static final TagKey RPC_CLIENT_METHOD = TagKey.create("method");
   public static final TagKey RPC_SERVER_METHOD = TagKey.create("method");
 
-  // Constants used to define the following MeasurementDescriptors.
-  private static final List<BasicUnit> bytes = Arrays.asList(BasicUnit.BYTES);
-  private static final List<BasicUnit> scalar = Arrays.asList(BasicUnit.SCALAR);
-  private static final List<BasicUnit> seconds = Arrays.asList(BasicUnit.SECONDS);
+  // Constants used to define the following Measures.
+  private static final String BYTE = "By";
+  private static final String COUNT = "1";
+  private static final String MILLISECOND = "ms";
 
-  // RPC client {@link MeasurementDescriptor}s.
-  public static final MeasurementDescriptor RPC_CLIENT_ERROR_COUNT =
-      MeasurementDescriptor.create(
+  // RPC client Measures.
+  public static final Measure RPC_CLIENT_ERROR_COUNT =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/error_count",
           "RPC Errors",
-          MeasurementUnit.create(0, scalar));
-  public static final MeasurementDescriptor RPC_CLIENT_REQUEST_BYTES =
-      MeasurementDescriptor.create(
+          COUNT);
+  public static final Measure RPC_CLIENT_REQUEST_BYTES =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/request_bytes",
           "Request bytes",
-          MeasurementUnit.create(0, bytes));
-  public static final MeasurementDescriptor RPC_CLIENT_RESPONSE_BYTES =
-      MeasurementDescriptor.create(
+          BYTE);
+  public static final Measure RPC_CLIENT_RESPONSE_BYTES =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/response_bytes",
           "Response bytes",
-          MeasurementUnit.create(0, bytes));
-  public static final MeasurementDescriptor RPC_CLIENT_ROUNDTRIP_LATENCY =
-      MeasurementDescriptor.create(
+          BYTE);
+  public static final Measure RPC_CLIENT_ROUNDTRIP_LATENCY =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/roundtrip_latency",
           "RPC roundtrip latency msec",
-          MeasurementUnit.create(-3, seconds));
-  public static final MeasurementDescriptor RPC_CLIENT_SERVER_ELAPSED_TIME =
-      MeasurementDescriptor.create(
+          MILLISECOND);
+  public static final Measure RPC_CLIENT_SERVER_ELAPSED_TIME =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/server_elapsed_time",
           "Server elapsed time in msecs",
-          MeasurementUnit.create(-3, seconds));
-  public static final MeasurementDescriptor RPC_CLIENT_UNCOMPRESSED_REQUEST_BYTES =
-      MeasurementDescriptor.create(
+          MILLISECOND);
+  public static final Measure RPC_CLIENT_UNCOMPRESSED_REQUEST_BYTES =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/uncompressed_request_bytes",
           "Uncompressed Request bytes",
-          MeasurementUnit.create(0, bytes));
-  public static final MeasurementDescriptor RPC_CLIENT_UNCOMPRESSED_RESPONSE_BYTES =
-      MeasurementDescriptor.create(
+          BYTE);
+  public static final Measure RPC_CLIENT_UNCOMPRESSED_RESPONSE_BYTES =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/uncompressed_response_bytes",
           "Uncompressed Response bytes",
-          MeasurementUnit.create(0, bytes));
-  public static final MeasurementDescriptor RPC_CLIENT_STARTED_COUNT =
-      MeasurementDescriptor.create(
+          BYTE);
+  public static final Measure RPC_CLIENT_STARTED_COUNT =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/started_count",
           "Number of client RPCs (streams) started",
-          MeasurementUnit.create(0, scalar));
-  public static final MeasurementDescriptor RPC_CLIENT_FINISHED_COUNT =
-      MeasurementDescriptor.create(
+          COUNT);
+  public static final Measure RPC_CLIENT_FINISHED_COUNT =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/finished_count",
           "Number of client RPCs (streams) finished",
-          MeasurementUnit.create(0, scalar));
-  public static final MeasurementDescriptor RPC_CLIENT_REQUEST_COUNT =
-      MeasurementDescriptor.create(
+          COUNT);
+  public static final Measure RPC_CLIENT_REQUEST_COUNT =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/request_count",
           "Number of client RPC request messages",
-          MeasurementUnit.create(0, scalar));
-  public static final MeasurementDescriptor RPC_CLIENT_RESPONSE_COUNT =
-      MeasurementDescriptor.create(
+          COUNT);
+  public static final Measure RPC_CLIENT_RESPONSE_COUNT =
+      Measure.DoubleMeasure.create(
           "grpc.io/client/response_count",
           "Number of client RPC response messages",
-          MeasurementUnit.create(0, scalar));
+          COUNT);
 
 
-  // RPC server {@link MeasurementDescriptor}s.
-  public static final MeasurementDescriptor RPC_SERVER_ERROR_COUNT =
-      MeasurementDescriptor.create(
+  // RPC server Measures.
+  public static final Measure RPC_SERVER_ERROR_COUNT =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/error_count",
           "RPC Errors",
-          MeasurementUnit.create(0, scalar));
-  public static final MeasurementDescriptor RPC_SERVER_REQUEST_BYTES =
-      MeasurementDescriptor.create(
+          COUNT);
+  public static final Measure RPC_SERVER_REQUEST_BYTES =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/request_bytes",
           "Request bytes",
-          MeasurementUnit.create(0, bytes));
-  public static final MeasurementDescriptor RPC_SERVER_RESPONSE_BYTES =
-      MeasurementDescriptor.create(
+          BYTE);
+  public static final Measure RPC_SERVER_RESPONSE_BYTES =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/response_bytes",
           "Response bytes",
-          MeasurementUnit.create(0, bytes));
-  public static final MeasurementDescriptor RPC_SERVER_SERVER_ELAPSED_TIME =
-      MeasurementDescriptor.create(
+          BYTE);
+  public static final Measure RPC_SERVER_SERVER_ELAPSED_TIME =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/server_elapsed_time",
           "Server elapsed time in msecs",
-          MeasurementUnit.create(-3, seconds));
-  public static final MeasurementDescriptor RPC_SERVER_SERVER_LATENCY =
-      MeasurementDescriptor.create(
+          MILLISECOND);
+  public static final Measure RPC_SERVER_SERVER_LATENCY =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/server_latency",
           "Latency in msecs",
-          MeasurementUnit.create(-3, seconds));
-  public static final MeasurementDescriptor RPC_SERVER_UNCOMPRESSED_REQUEST_BYTES =
-      MeasurementDescriptor.create(
+          MILLISECOND);
+  public static final Measure RPC_SERVER_UNCOMPRESSED_REQUEST_BYTES =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/uncompressed_request_bytes",
           "Uncompressed Request bytes",
-          MeasurementUnit.create(0, bytes));
-  public static final MeasurementDescriptor RPC_SERVER_UNCOMPRESSED_RESPONSE_BYTES =
-      MeasurementDescriptor.create(
+          BYTE);
+  public static final Measure RPC_SERVER_UNCOMPRESSED_RESPONSE_BYTES =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/uncompressed_response_bytes",
           "Uncompressed Response bytes",
-          MeasurementUnit.create(0, bytes));
-  public static final MeasurementDescriptor RPC_SERVER_STARTED_COUNT =
-      MeasurementDescriptor.create(
+          BYTE);
+  public static final Measure RPC_SERVER_STARTED_COUNT =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/started_count",
           "Number of server RPCs (streams) started",
-          MeasurementUnit.create(0, scalar));
-  public static final MeasurementDescriptor RPC_SERVER_FINISHED_COUNT =
-      MeasurementDescriptor.create(
+          COUNT);
+  public static final Measure RPC_SERVER_FINISHED_COUNT =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/finished_count",
           "Number of server RPCs (streams) finished",
-          MeasurementUnit.create(0, scalar));
-  public static final MeasurementDescriptor RPC_SERVER_REQUEST_COUNT =
-      MeasurementDescriptor.create(
+          COUNT);
+  public static final Measure RPC_SERVER_REQUEST_COUNT =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/request_count",
           "Number of server RPC request messages",
-          MeasurementUnit.create(0, scalar));
-  public static final MeasurementDescriptor RPC_SERVER_RESPONSE_COUNT =
-      MeasurementDescriptor.create(
+          COUNT);
+  public static final Measure RPC_SERVER_RESPONSE_COUNT =
+      Measure.DoubleMeasure.create(
           "grpc.io/server/response_count",
           "Number of server RPC response messages",
-          MeasurementUnit.create(0, scalar));
+          COUNT);
 
   // Visible for testing.
   RpcMeasurementConstants() {
diff --git a/core/src/main/java/io/opencensus/stats/ViewDescriptor.java b/core/src/main/java/io/opencensus/stats/ViewDescriptor.java
index bef15cc5..22859ce6 100644
--- a/core/src/main/java/io/opencensus/stats/ViewDescriptor.java
+++ b/core/src/main/java/io/opencensus/stats/ViewDescriptor.java
@@ -46,10 +46,10 @@ public abstract class ViewDescriptor {
   /**
    * Measurement type of this view.
    */
-  public abstract MeasurementDescriptor getMeasurementDescriptor();
+  public abstract Measure getMeasure();
 
   /**
-   * Tag keys to match with the associated {@link MeasurementDescriptor}. If no keys are specified,
+   * Tag keys to match with the associated {@link Measure}. If no keys are specified,
    * then all stats are recorded. Keys must be unique.
    *
    * <p>Note: The returned list is unmodifiable, attempts to update it will throw an
@@ -104,13 +104,13 @@ public abstract class ViewDescriptor {
     public static DistributionViewDescriptor create(
         String name,
         String description,
-        MeasurementDescriptor measurementDescriptor,
+        Measure measure,
         DistributionAggregationDescriptor distributionAggregationDescriptor,
         List<TagKey> tagKeys) {
       return create(
           Name.create(name),
           description,
-          measurementDescriptor,
+          measure,
           distributionAggregationDescriptor,
           tagKeys);
     }
@@ -121,13 +121,13 @@ public abstract class ViewDescriptor {
     public static DistributionViewDescriptor create(
         Name name,
         String description,
-        MeasurementDescriptor measurementDescriptor,
+        Measure measure,
         DistributionAggregationDescriptor distributionAggregationDescriptor,
         List<TagKey> tagKeys) {
       return new AutoValue_ViewDescriptor_DistributionViewDescriptor(
           name,
           description,
-          measurementDescriptor,
+          measure,
           Collections.unmodifiableList(new ArrayList<TagKey>(tagKeys)),
           distributionAggregationDescriptor);
     }
@@ -158,13 +158,13 @@ public abstract class ViewDescriptor {
     public static IntervalViewDescriptor create(
         String name,
         String description,
-        MeasurementDescriptor measurementDescriptor,
+        Measure measure,
         IntervalAggregationDescriptor intervalAggregationDescriptor,
         List<TagKey> tagKeys) {
       return create(
           Name.create(name),
           description,
-          measurementDescriptor,
+          measure,
           intervalAggregationDescriptor,
           tagKeys);
     }
@@ -175,13 +175,13 @@ public abstract class ViewDescriptor {
     public static IntervalViewDescriptor create(
         Name name,
         String description,
-        MeasurementDescriptor measurementDescriptor,
+        Measure measure,
         IntervalAggregationDescriptor intervalAggregationDescriptor,
         List<TagKey> tagKeys) {
       return new AutoValue_ViewDescriptor_IntervalViewDescriptor(
           name,
           description,
-          measurementDescriptor,
+          measure,
           Collections.unmodifiableList(new ArrayList<TagKey>(tagKeys)),
           intervalAggregationDescriptor);
     }
diff --git a/core/src/test/java/io/opencensus/stats/MeasureTest.java b/core/src/test/java/io/opencensus/stats/MeasureTest.java
new file mode 100644
index 00000000..aff4c873
--- /dev/null
+++ b/core/src/test/java/io/opencensus/stats/MeasureTest.java
@@ -0,0 +1,116 @@
+/*
+ * Copyright 2016, Google Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.opencensus.stats;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.testing.EqualsTester;
+import io.opencensus.internal.StringUtil;
+import java.util.Arrays;
+import org.junit.Ignore;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Tests for {@link Measure}
+ */
+@RunWith(JUnit4.class)
+public final class MeasureTest {
+
+  @Ignore  // TODO: determine whether there are any restrictions on measure names.
+  @Test
+  public void testNameMaxLength() {
+    char[] name = new char[StringUtil.MAX_LENGTH];
+    char[] truncName = new char[StringUtil.MAX_LENGTH + 10];
+    Arrays.fill(name, 'n');
+    Arrays.fill(truncName, 'n');
+    assertThat(makeSimpleMeasure(new String(name)).getName())
+        .isEqualTo(makeSimpleMeasure(new String(truncName)).getName());
+  }
+
+  @Ignore  // TODO: determine whether there are any restrictions on measure names.
+  @Test
+  public void testNameBadChar() {
+    assertThat(makeSimpleMeasure("\2ab\3cd").getName())
+        .isEqualTo(StringUtil.UNPRINTABLE_CHAR_SUBSTITUTE + "ab"
+            + StringUtil.UNPRINTABLE_CHAR_SUBSTITUTE + "cd");
+  }
+
+  @Test
+  public void testDoubleMeasureComponents() {
+    Measure measurement = Measure.DoubleMeasure.create(
+        "Foo",
+        "The description of Foo",
+        "Mbit/s");
+    assertThat(measurement.getName()).isEqualTo("Foo");
+    assertThat(measurement.getDescription()).isEqualTo("The description of Foo");
+    assertThat(measurement.getUnit()).isEqualTo("Mbit/s");
+  }
+
+  @Test
+  public void testLongMeasureComponents() {
+    Measure measurement = Measure.LongMeasure.create(
+        "Bar",
+        "The description of Bar",
+        "1");
+    assertThat(measurement.getName()).isEqualTo("Bar");
+    assertThat(measurement.getDescription()).isEqualTo("The description of Bar");
+    assertThat(measurement.getUnit()).isEqualTo("1");
+  }
+
+  @Test
+  public void testDoubleMeasureEquals() {
+    new EqualsTester()
+        .addEqualityGroup(
+            Measure.DoubleMeasure.create(
+                "name",
+                "description",
+                "bit/s"),
+            Measure.DoubleMeasure.create(
+                "name",
+                "description",
+                "bit/s"))
+        .addEqualityGroup(
+            Measure.DoubleMeasure.create(
+                "name",
+                "description 2",
+                "bit/s"))
+        .testEquals();
+  }
+
+  @Test
+  public void testLongMeasureEquals() {
+    new EqualsTester()
+        .addEqualityGroup(
+            Measure.LongMeasure.create(
+                "name",
+                "description",
+                "bit/s"),
+            Measure.LongMeasure.create(
+                "name",
+                "description",
+                "bit/s"))
+        .addEqualityGroup(
+            Measure.LongMeasure.create(
+                "name",
+                "description 2",
+                "bit/s"))
+        .testEquals();
+  }
+
+  private static final Measure makeSimpleMeasure(String name) {
+    return Measure.DoubleMeasure.create(name, name + " description", "1");
+  }
+}
diff --git a/core/src/test/java/io/opencensus/stats/MeasurementDescriptorTest.java b/core/src/test/java/io/opencensus/stats/MeasurementDescriptorTest.java
deleted file mode 100644
index 47b6bc57..00000000
--- a/core/src/test/java/io/opencensus/stats/MeasurementDescriptorTest.java
+++ /dev/null
@@ -1,126 +0,0 @@
-/*
- * Copyright 2016, Google Inc.
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *     http://www.apache.org/licenses/LICENSE-2.0
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.opencensus.stats;
-
-import static com.google.common.truth.Truth.assertThat;
-
-import com.google.common.testing.EqualsTester;
-import io.opencensus.internal.StringUtil;
-import io.opencensus.stats.MeasurementDescriptor.BasicUnit;
-import io.opencensus.stats.MeasurementDescriptor.MeasurementUnit;
-import java.util.Arrays;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
-
-/**
- * Tests for {@link MeasurementDescriptor}
- */
-@RunWith(JUnit4.class)
-public final class MeasurementDescriptorTest {
-  @Test
-  public void testNameMaxLength() {
-    char[] name = new char[MeasurementDescriptor.MAX_LENGTH];
-    char[] truncName = new char[MeasurementDescriptor.MAX_LENGTH + 10];
-    Arrays.fill(name, 'n');
-    Arrays.fill(truncName, 'n');
-    assertThat(makeSimpleDescriptor(new String(name)).getName())
-        .isEqualTo(makeSimpleDescriptor(new String(truncName)).getName());
-  }
-
-  @Test
-  public void testNameBadChar() {
-    assertThat(makeSimpleDescriptor("\2ab\3cd").getName())
-        .isEqualTo(StringUtil.UNPRINTABLE_CHAR_SUBSTITUTE + "ab"
-                 + StringUtil.UNPRINTABLE_CHAR_SUBSTITUTE + "cd");
-  }
-
-  @Test
-  public void testComponents() {
-    MeasurementDescriptor measurement = MeasurementDescriptor.create(
-        "Foo",
-        "The description of Foo",
-        MeasurementUnit.create(
-            6, Arrays.asList(BasicUnit.BITS), Arrays.asList(BasicUnit.SECONDS)));
-    assertThat(measurement.getName()).isEqualTo("Foo");
-    assertThat(measurement.getMeasurementDescriptorName())
-        .isEqualTo(MeasurementDescriptor.Name.create("Foo"));
-    assertThat(measurement.getDescription()).isEqualTo("The description of Foo");
-    assertThat(measurement.getUnit().getPower10()).isEqualTo(6);
-    assertThat(measurement.getUnit().getNumerators()).hasSize(1);
-    assertThat(measurement.getUnit().getNumerators().get(0)).isEqualTo(BasicUnit.BITS);
-    assertThat(measurement.getUnit().getDenominators()).hasSize(1);
-    assertThat(measurement.getUnit().getDenominators().get(0)).isEqualTo(BasicUnit.SECONDS);
-  }
-
-  @Test
-  public void testMeasurementDescriptorNameSanitization() {
-    assertThat(MeasurementDescriptor.Name.create("md\1").asString())
-        .isEqualTo("md" + StringUtil.UNPRINTABLE_CHAR_SUBSTITUTE);
-  }
-
-  @Test
-  public void testMeasurementDescriptorNameEquals() {
-    new EqualsTester()
-        .addEqualityGroup(
-            MeasurementDescriptor.Name.create("md1"), MeasurementDescriptor.Name.create("md1"))
-        .addEqualityGroup(MeasurementDescriptor.Name.create("md2"))
-        .testEquals();
-  }
-
-  @Test
-  public void testMeasurementUnitEquals() {
-    new EqualsTester()
-        .addEqualityGroup(
-            MeasurementUnit.create(
-                1, Arrays.asList(BasicUnit.BYTES), Arrays.asList(BasicUnit.SECONDS)),
-            MeasurementUnit.create(
-                1, Arrays.asList(BasicUnit.BYTES), Arrays.asList(BasicUnit.SECONDS)))
-        .addEqualityGroup(
-            MeasurementUnit.create(
-                2, Arrays.asList(BasicUnit.BYTES), Arrays.asList(BasicUnit.SECONDS)))
-        .addEqualityGroup(MeasurementUnit.create(1, Arrays.asList(BasicUnit.BYTES)))
-        .testEquals();
-  }
-
-  @Test
-  public void testMeasurementDescriptorEquals() {
-    new EqualsTester()
-        .addEqualityGroup(
-            MeasurementDescriptor.create(
-                "name",
-                "description",
-                MeasurementUnit.create(
-                    1, Arrays.asList(BasicUnit.BITS), Arrays.asList(BasicUnit.SECONDS))),
-            MeasurementDescriptor.create(
-                MeasurementDescriptor.Name.create("name"),
-                "description",
-                MeasurementUnit.create(
-                    1, Arrays.asList(BasicUnit.BITS), Arrays.asList(BasicUnit.SECONDS))))
-        .addEqualityGroup(
-            MeasurementDescriptor.create(
-                "name",
-                "description 2",
-                MeasurementUnit.create(
-                    1, Arrays.asList(BasicUnit.BYTES), Arrays.asList(BasicUnit.SECONDS))))
-        .testEquals();
-  }
-
-  private static final MeasurementDescriptor makeSimpleDescriptor(String name) {
-    return MeasurementDescriptor.create(
-        name,
-        name + " description",
-        MeasurementUnit.create(1, Arrays.asList(BasicUnit.SCALAR)));
-  }
-}
diff --git a/core/src/test/java/io/opencensus/stats/MeasurementMapTest.java b/core/src/test/java/io/opencensus/stats/MeasurementMapTest.java
index 0f9f52f1..ad5af9ba 100644
--- a/core/src/test/java/io/opencensus/stats/MeasurementMapTest.java
+++ b/core/src/test/java/io/opencensus/stats/MeasurementMapTest.java
@@ -16,10 +16,7 @@ package io.opencensus.stats;
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.collect.ImmutableList;
-import io.opencensus.stats.MeasurementDescriptor.BasicUnit;
-import io.opencensus.stats.MeasurementDescriptor.MeasurementUnit;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Iterator;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -68,14 +65,14 @@ public class MeasurementMapTest {
     ArrayList<MeasurementValue> expected = new ArrayList<MeasurementValue>(10);
     MeasurementMap.Builder builder = MeasurementMap.builder();
     for (int i = 1; i <= 10; i++) {
-      expected.add(MeasurementValue.create(makeSimpleMeasurement("m" + i), i * 11.1));
-      builder.put(makeSimpleMeasurement("m" + i), i * 11.1);
+      expected.add(MeasurementValue.create(makeSimpleMeasure("m" + i), i * 11.1));
+      builder.put(makeSimpleMeasure("m" + i), i * 11.1);
       assertEquals(expected, builder.build());
     }
   }
 
   @Test
-  public void testDuplicateMeasurementDescriptors() {
+  public void testDuplicateMeasures() {
     assertEquals(MeasurementMap.of(M1, 1.0, M1, 1.0), MeasurementMap.of(M1, 1.0));
     assertEquals(MeasurementMap.of(M1, 1.0, M1, 2.0), MeasurementMap.of(M1, 1.0));
     assertEquals(MeasurementMap.of(M1, 1.0, M1, 2.0, M1, 3.0), MeasurementMap.of(M1, 1.0));
@@ -87,20 +84,18 @@ public class MeasurementMapTest {
   public void testSize() {
     MeasurementMap.Builder builder = MeasurementMap.builder();
     for (int i = 1; i <= 10; i++) {
-      builder.put(makeSimpleMeasurement("m" + i), i * 11.1);
+      builder.put(makeSimpleMeasure("m" + i), i * 11.1);
       assertThat(builder.build()).hasSize(i);
     }
   }
 
-  private static final MeasurementUnit simpleMeasurementUnit =
-      MeasurementUnit.create(1, Arrays.asList(BasicUnit.SCALAR));
-  private static final MeasurementDescriptor M1 = makeSimpleMeasurement("m1");
-  private static final MeasurementDescriptor M2 = makeSimpleMeasurement("m2");
-  private static final MeasurementDescriptor M3 = makeSimpleMeasurement("m3");
+  private static final Measure M1 = makeSimpleMeasure("m1");
+  private static final Measure M2 = makeSimpleMeasure("m2");
+  private static final Measure M3 = makeSimpleMeasure("m3");
 
-  private static final MeasurementDescriptor makeSimpleMeasurement(String measurement) {
-    return MeasurementDescriptor.create(
-        measurement, measurement + " description", simpleMeasurementUnit);
+  private static final Measure makeSimpleMeasure(String measure) {
+    return Measure.DoubleMeasure.create(
+        measure, measure + " description", "1");
   }
 
   private static void assertEquals(
@@ -110,8 +105,8 @@ public class MeasurementMapTest {
     while (e.hasNext() && a.hasNext()) {
       MeasurementValue expectedMeasurement = e.next();
       MeasurementValue actualMeasurement = a.next();
-      assertThat(expectedMeasurement.getMeasurement().getMeasurementDescriptorName())
-          .isEqualTo(actualMeasurement.getMeasurement().getMeasurementDescriptorName());
+      assertThat(expectedMeasurement.getMeasurement().getName())
+          .isEqualTo(actualMeasurement.getMeasurement().getName());
       assertThat(expectedMeasurement.getValue())
           .isWithin(0.00000001).of(actualMeasurement.getValue());
     }
diff --git a/core/src/test/java/io/opencensus/stats/ViewDescriptorTest.java b/core/src/test/java/io/opencensus/stats/ViewDescriptorTest.java
index c0ee7143..e8c5cd80 100644
--- a/core/src/test/java/io/opencensus/stats/ViewDescriptorTest.java
+++ b/core/src/test/java/io/opencensus/stats/ViewDescriptorTest.java
@@ -19,8 +19,6 @@ import static org.junit.Assert.assertTrue;
 import com.google.common.testing.EqualsTester;
 import io.opencensus.common.Duration;
 import io.opencensus.common.Function;
-import io.opencensus.stats.MeasurementDescriptor.BasicUnit;
-import io.opencensus.stats.MeasurementDescriptor.MeasurementUnit;
 import io.opencensus.stats.ViewDescriptor.DistributionViewDescriptor;
 import io.opencensus.stats.ViewDescriptor.IntervalViewDescriptor;
 import java.util.Arrays;
@@ -38,13 +36,13 @@ public final class ViewDescriptorTest {
   public void testDistributionViewDescriptor() {
     DistributionAggregationDescriptor dAggrDescriptor = DistributionAggregationDescriptor.create();
     final ViewDescriptor viewDescriptor = DistributionViewDescriptor.create(
-        name, description, measurementDescriptor, dAggrDescriptor, keys);
+        name, description, measure, dAggrDescriptor, keys);
 
     assertThat(viewDescriptor.getViewDescriptorName()).isEqualTo(name);
     assertThat(viewDescriptor.getName()).isEqualTo(name.asString());
     assertThat(viewDescriptor.getDescription()).isEqualTo(description);
-    assertThat(viewDescriptor.getMeasurementDescriptor().getMeasurementDescriptorName())
-        .isEqualTo(measurementDescriptor.getMeasurementDescriptorName());
+    assertThat(viewDescriptor.getMeasure().getName())
+        .isEqualTo(measure.getName());
     assertThat(viewDescriptor.getTagKeys()).hasSize(2);
     assertThat(viewDescriptor.getTagKeys().get(0).toString()).isEqualTo("foo");
     assertThat(viewDescriptor.getTagKeys().get(1).toString()).isEqualTo("bar");
@@ -66,13 +64,13 @@ public final class ViewDescriptorTest {
     IntervalAggregationDescriptor iAggrDescriptor = IntervalAggregationDescriptor.create(
         Arrays.asList(Duration.fromMillis(1), Duration.fromMillis(22), Duration.fromMillis(333)));
     final ViewDescriptor viewDescriptor = IntervalViewDescriptor.create(
-        name, description, measurementDescriptor, iAggrDescriptor, keys);
+        name, description, measure, iAggrDescriptor, keys);
 
     assertThat(viewDescriptor.getViewDescriptorName()).isEqualTo(name);
     assertThat(viewDescriptor.getName()).isEqualTo(name.asString());
     assertThat(viewDescriptor.getDescription()).isEqualTo(description);
-    assertThat(viewDescriptor.getMeasurementDescriptor().getMeasurementDescriptorName())
-        .isEqualTo(measurementDescriptor.getMeasurementDescriptorName());
+    assertThat(viewDescriptor.getMeasure().getName())
+        .isEqualTo(measure.getName());
     assertThat(viewDescriptor.getTagKeys()).hasSize(2);
     assertThat(viewDescriptor.getTagKeys().get(0).toString()).isEqualTo("foo");
     assertThat(viewDescriptor.getTagKeys().get(1).toString()).isEqualTo("bar");
@@ -97,20 +95,20 @@ public final class ViewDescriptorTest {
     new EqualsTester()
         .addEqualityGroup(
             DistributionViewDescriptor.create(
-                name, description, measurementDescriptor, dAggrDescriptor, keys),
+                name, description, measure, dAggrDescriptor, keys),
             DistributionViewDescriptor.create(
-                name, description, measurementDescriptor, dAggrDescriptor, keys))
+                name, description, measure, dAggrDescriptor, keys))
         .addEqualityGroup(
             DistributionViewDescriptor.create(
-                name, description + 2, measurementDescriptor, dAggrDescriptor, keys))
+                name, description + 2, measure, dAggrDescriptor, keys))
         .addEqualityGroup(
             IntervalViewDescriptor.create(
-                name, description, measurementDescriptor, iAggrDescriptor, keys),
+                name, description, measure, iAggrDescriptor, keys),
             IntervalViewDescriptor.create(
-                name, description, measurementDescriptor, iAggrDescriptor, keys))
+                name, description, measure, iAggrDescriptor, keys))
         .addEqualityGroup(
             IntervalViewDescriptor.create(
-                name, description + 2, measurementDescriptor, iAggrDescriptor, keys))
+                name, description + 2, measure, iAggrDescriptor, keys))
         .testEquals();
   }
 
@@ -119,7 +117,7 @@ public final class ViewDescriptorTest {
     DistributionViewDescriptor.create(
         (ViewDescriptor.Name) null,
         description,
-        measurementDescriptor,
+        measure,
         DistributionAggregationDescriptor.create(),
         keys);
   }
@@ -129,7 +127,7 @@ public final class ViewDescriptorTest {
     DistributionViewDescriptor.create(
         (String) null,
         description,
-        measurementDescriptor,
+        measure,
         DistributionAggregationDescriptor.create(),
         keys);
   }
@@ -139,7 +137,7 @@ public final class ViewDescriptorTest {
     IntervalViewDescriptor.create(
         (ViewDescriptor.Name) null,
         description,
-        measurementDescriptor,
+        measure,
         IntervalAggregationDescriptor.create(Arrays.asList(Duration.fromMillis(1))),
         keys);
   }
@@ -149,7 +147,7 @@ public final class ViewDescriptorTest {
     IntervalViewDescriptor.create(
         (String) null,
         description,
-        measurementDescriptor,
+        measure,
         IntervalAggregationDescriptor.create(Arrays.asList(Duration.fromMillis(1))),
         keys);
   }
@@ -175,9 +173,9 @@ public final class ViewDescriptorTest {
 
   private final ViewDescriptor.Name name = ViewDescriptor.Name.create("test-view-name");
   private final String description = "test-view-name description";
-  private final MeasurementDescriptor measurementDescriptor = MeasurementDescriptor.create(
+  private final Measure measure = Measure.DoubleMeasure.create(
       "measurement",
       "measurement description",
-      MeasurementUnit.create(1, Arrays.asList(BasicUnit.SCALAR)));
+      "1");
   private final List<TagKey> keys = Arrays.asList(TagKey.create("foo"), TagKey.create("bar"));
 }
diff --git a/core/src/test/java/io/opencensus/stats/ViewTest.java b/core/src/test/java/io/opencensus/stats/ViewTest.java
index 1089af5d..6a42c01a 100644
--- a/core/src/test/java/io/opencensus/stats/ViewTest.java
+++ b/core/src/test/java/io/opencensus/stats/ViewTest.java
@@ -22,8 +22,6 @@ import io.opencensus.common.Function;
 import io.opencensus.common.Timestamp;
 import io.opencensus.stats.DistributionAggregation.Range;
 import io.opencensus.stats.IntervalAggregation.Interval;
-import io.opencensus.stats.MeasurementDescriptor.BasicUnit;
-import io.opencensus.stats.MeasurementDescriptor.MeasurementUnit;
 import io.opencensus.stats.View.DistributionView;
 import io.opencensus.stats.View.IntervalView;
 import io.opencensus.stats.ViewDescriptor.DistributionViewDescriptor;
@@ -46,7 +44,7 @@ public final class ViewTest {
         DistributionAggregationDescriptor.create(Arrays.asList(10.0, 20.0, 30.0, 40.0));
     final DistributionViewDescriptor viewDescriptor =
         DistributionViewDescriptor.create(
-            name, description, measurementDescriptor, aggregationDescriptor, tagKeys);
+            name, description, measure, aggregationDescriptor, tagKeys);
     final List<DistributionAggregation> aggregations = Arrays.asList(
         DistributionAggregation.create(5, 5.0, 15.0, Range.create(1.0, 5.0), tags1,
             Arrays.asList(1L, 1L, 1L, 1L, 1L)),
@@ -80,7 +78,7 @@ public final class ViewTest {
         IntervalAggregationDescriptor.create(Arrays.asList(Duration.fromMillis(111)));
     final IntervalViewDescriptor viewDescriptor =
         IntervalViewDescriptor.create(
-            name, description, measurementDescriptor, aggregationDescriptor, tagKeys);
+            name, description, measure, aggregationDescriptor, tagKeys);
     final List<IntervalAggregation> aggregations = Arrays.asList(
         IntervalAggregation.create(tags1, Arrays.asList(
             Interval.create(Duration.fromMillis(111), 10, 100))),
@@ -110,7 +108,7 @@ public final class ViewTest {
         DistributionViewDescriptor.create(
             name,
             description,
-            measurementDescriptor,
+            measure,
             DistributionAggregationDescriptor.create(Arrays.asList(10.0)),
             tagKeys);
     List<DistributionAggregation> dAggregations =
@@ -121,7 +119,7 @@ public final class ViewTest {
         IntervalViewDescriptor.create(
             name,
             description,
-            measurementDescriptor,
+            measure,
             IntervalAggregationDescriptor.create(Arrays.asList(Duration.fromMillis(111))),
             tagKeys);
     List<IntervalAggregation> iAggregations =
@@ -175,10 +173,10 @@ public final class ViewTest {
   // description
   private final String description = "test-view-descriptor description";
   // measurement descriptor
-  private final MeasurementDescriptor measurementDescriptor = MeasurementDescriptor.create(
+  private final Measure measure = Measure.DoubleMeasure.create(
       "measurement-descriptor",
       "measurement-descriptor description",
-      MeasurementUnit.create(1, Arrays.asList(BasicUnit.SCALAR)));
+      "1");
 
   private static final <T> boolean shallowListEquals(List<T> l1, List <T> l2) {
     if (l1.size() != l2.size()) {
diff --git a/core_impl/src/main/java/io/opencensus/stats/MeasurementDescriptorToViewMap.java b/core_impl/src/main/java/io/opencensus/stats/MeasureToViewMap.java
index 5b39ef97..128c1f52 100644
--- a/core_impl/src/main/java/io/opencensus/stats/MeasurementDescriptorToViewMap.java
+++ b/core_impl/src/main/java/io/opencensus/stats/MeasureToViewMap.java
@@ -28,18 +28,18 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.GuardedBy;
 
 /**
- * A class that stores a singleton map from {@link MeasurementDescriptor.Name}s to {@link
+ * A class that stores a singleton map from {@code MeasureName}s to {@link
  * MutableView}s.
  */
-final class MeasurementDescriptorToViewMap {
+final class MeasureToViewMap {
 
   /*
-   * A synchronized singleton map that stores the one-to-many mapping from MeasurementDescriptors
+   * A synchronized singleton map that stores the one-to-many mapping from Measures
    * to MutableViews.
    */
   @GuardedBy("this")
-  private final Multimap<MeasurementDescriptor.Name, MutableView> mutableMap =
-      HashMultimap.<MeasurementDescriptor.Name, MutableView>create();
+  private final Multimap<String, MutableView> mutableMap =
+      HashMultimap.<String, MutableView>create();
 
   @GuardedBy("this")
   private final Map<ViewDescriptor.Name, ViewDescriptor> registeredViews =
@@ -58,7 +58,7 @@ final class MeasurementDescriptorToViewMap {
       return null;
     }
     Collection<MutableView> views =
-        mutableMap.get(viewDescriptor.getMeasurementDescriptor().getMeasurementDescriptorName());
+        mutableMap.get(viewDescriptor.getMeasure().getName());
     for (MutableView view : views) {
       if (view.getViewDescriptor().getViewDescriptorName().equals(viewName)) {
         return view;
@@ -86,14 +86,14 @@ final class MeasurementDescriptorToViewMap {
             new CreateMutableDistributionViewFunction(clock),
             new CreateMutableIntervalViewFunction());
     mutableMap.put(
-        viewDescriptor.getMeasurementDescriptor().getMeasurementDescriptorName(), mutableView);
+        viewDescriptor.getMeasure().getName(), mutableView);
   }
 
   // Records stats with a set of tags.
   synchronized void record(StatsContextImpl tags, MeasurementMap stats) {
     for (MeasurementValue mv : stats) {
       Collection<MutableView> views =
-          mutableMap.get(mv.getMeasurement().getMeasurementDescriptorName());
+          mutableMap.get(mv.getMeasurement().getName());
       for (MutableView view : views) {
         view.record(tags, mv.getValue());
       }
diff --git a/core_impl/src/main/java/io/opencensus/stats/StatsManager.java b/core_impl/src/main/java/io/opencensus/stats/StatsManager.java
index 97b1c30d..7197826d 100644
--- a/core_impl/src/main/java/io/opencensus/stats/StatsManager.java
+++ b/core_impl/src/main/java/io/opencensus/stats/StatsManager.java
@@ -25,8 +25,8 @@ final class StatsManager {
   // clock used throughout the stats implementation
   private final Clock clock;
 
-  private final MeasurementDescriptorToViewMap measurementDescriptorToViewMap =
-      new MeasurementDescriptorToViewMap();
+  private final MeasureToViewMap measureToViewMap =
+      new MeasureToViewMap();
 
   StatsManager(EventQueue queue, Clock clock) {
     this.queue = queue;
@@ -40,11 +40,11 @@ final class StatsManager {
       throw new UnsupportedOperationException(
           "The prototype will only support distribution views.");
     }
-    measurementDescriptorToViewMap.registerView(viewDescriptor, clock);
+    measureToViewMap.registerView(viewDescriptor, clock);
   }
 
   View getView(ViewDescriptor.Name viewName) {
-    View view = measurementDescriptorToViewMap.getView(viewName, clock);
+    View view = measureToViewMap.getView(viewName, clock);
     if (view == null) {
       throw new IllegalArgumentException(
           "View for view descriptor " + viewName + " not found.");
@@ -71,7 +71,7 @@ final class StatsManager {
 
     @Override
     public void process() {
-      viewManager.measurementDescriptorToViewMap.record(tags, stats);
+      viewManager.measureToViewMap.record(tags, stats);
     }
   }
 }
diff --git a/core_impl/src/test/java/io/opencensus/stats/MeasurementDescriptorToViewMapTest.java b/core_impl/src/test/java/io/opencensus/stats/MeasureToViewMapTest.java
index 0f61803e..2d691e7f 100644
--- a/core_impl/src/test/java/io/opencensus/stats/MeasurementDescriptorToViewMapTest.java
+++ b/core_impl/src/test/java/io/opencensus/stats/MeasureToViewMapTest.java
@@ -18,8 +18,6 @@ import static org.junit.Assert.fail;
 
 import io.opencensus.common.Function;
 import io.opencensus.common.Timestamp;
-import io.opencensus.stats.MeasurementDescriptor.BasicUnit;
-import io.opencensus.stats.MeasurementDescriptor.MeasurementUnit;
 import io.opencensus.stats.View.DistributionView;
 import io.opencensus.stats.View.IntervalView;
 import io.opencensus.stats.ViewDescriptor.DistributionViewDescriptor;
@@ -29,15 +27,15 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
 
-/** Tests for {@link MeasurementDescriptorToViewMap}. */
+/** Tests for {@link MeasureToViewMap}. */
 @RunWith(JUnit4.class)
-public class MeasurementDescriptorToViewMapTest {
+public class MeasureToViewMapTest {
 
-  private static final MeasurementDescriptor MEASUREMENT_DESCRIPTOR =
-      MeasurementDescriptor.create(
+  private static final Measure MEASUREMENT_DESCRIPTOR =
+      Measure.DoubleMeasure.create(
           "my measurement",
           "measurement description",
-          MeasurementUnit.create(0, Arrays.asList(BasicUnit.BYTES)));
+          "By");
 
   private static final ViewDescriptor.Name VIEW_NAME = ViewDescriptor.Name.create("my view");
 
@@ -51,12 +49,12 @@ public class MeasurementDescriptorToViewMapTest {
 
   @Test
   public void testRegisterAndGetDistributionView() {
-    MeasurementDescriptorToViewMap measurementDescriptorToViewMap =
-        new MeasurementDescriptorToViewMap();
+    MeasureToViewMap measureToViewMap =
+        new MeasureToViewMap();
     TestClock clock = TestClock.create(Timestamp.create(10, 20));
-    measurementDescriptorToViewMap.registerView(VIEW_DESCRIPTOR, clock);
+    measureToViewMap.registerView(VIEW_DESCRIPTOR, clock);
     clock.setTime(Timestamp.create(30, 40));
-    View actual = measurementDescriptorToViewMap.getView(VIEW_NAME, clock);
+    View actual = measureToViewMap.getView(VIEW_NAME, clock);
     actual.match(
         new Function<View.DistributionView, Void>() {
           @Override
diff --git a/core_impl/src/test/java/io/opencensus/stats/ViewManagerImplTest.java b/core_impl/src/test/java/io/opencensus/stats/ViewManagerImplTest.java
index c4d3f98d..f784d98c 100644
--- a/core_impl/src/test/java/io/opencensus/stats/ViewManagerImplTest.java
+++ b/core_impl/src/test/java/io/opencensus/stats/ViewManagerImplTest.java
@@ -19,8 +19,6 @@ import static io.opencensus.stats.StatsTestUtil.createContext;
 import io.opencensus.common.Duration;
 import io.opencensus.common.Timestamp;
 import io.opencensus.internal.SimpleEventQueue;
-import io.opencensus.stats.MeasurementDescriptor.BasicUnit;
-import io.opencensus.stats.MeasurementDescriptor.MeasurementUnit;
 import io.opencensus.stats.View.DistributionView;
 import io.opencensus.stats.ViewDescriptor.DistributionViewDescriptor;
 import io.opencensus.stats.ViewDescriptor.IntervalViewDescriptor;
@@ -45,19 +43,16 @@ public class ViewManagerImplTest {
   private static final TagValue VALUE = TagValue.create("VALUE");
   private static final TagValue VALUE_2 = TagValue.create("VALUE_2");
 
-  private static final MeasurementDescriptor.Name MEASUREMENT_NAME =
-      MeasurementDescriptor.Name.create("my measurement");
+  private static final String MEASUREMENT_NAME = "my measurement";
 
-  private static final MeasurementDescriptor.Name MEASUREMENT_NAME_2 =
-      MeasurementDescriptor.Name.create("my measurement 2");
+  private static final String MEASUREMENT_NAME_2 = "my measurement 2";
 
-  private static final MeasurementUnit MEASUREMENT_UNIT =
-      MeasurementUnit.create(-6, Arrays.asList(BasicUnit.SECONDS));
+  private static final String MEASUREMENT_UNIT = "us";
 
   private static final String MEASUREMENT_DESCRIPTION = "measurement description";
 
-  private static final MeasurementDescriptor MEASUREMENT_DESCRIPTOR =
-      MeasurementDescriptor.create(MEASUREMENT_NAME, MEASUREMENT_DESCRIPTION, MEASUREMENT_UNIT);
+  private static final Measure MEASUREMENT_DESCRIPTOR =
+      Measure.DoubleMeasure.create(MEASUREMENT_NAME, MEASUREMENT_DESCRIPTION, MEASUREMENT_UNIT);
 
   private static final ViewDescriptor.Name VIEW_NAME = ViewDescriptor.Name.create("my view");
   private static final ViewDescriptor.Name VIEW_NAME_2 = ViewDescriptor.Name.create("my view 2");
@@ -88,7 +83,7 @@ public class ViewManagerImplTest {
 
   private static DistributionViewDescriptor createDistributionViewDescriptor(
       ViewDescriptor.Name name,
-      MeasurementDescriptor measureDescr,
+      Measure measureDescr,
       DistributionAggregationDescriptor aggDescr,
       List<TagKey> keys) {
     return DistributionViewDescriptor.create(name, VIEW_DESCRIPTION, measureDescr, aggDescr, keys);
@@ -282,11 +277,11 @@ public class ViewManagerImplTest {
     viewManager.registerView(
         createDistributionViewDescriptor(
             VIEW_NAME,
-            MeasurementDescriptor.create(MEASUREMENT_NAME, "measurement", MEASUREMENT_UNIT),
+            Measure.DoubleMeasure.create(MEASUREMENT_NAME, "measurement", MEASUREMENT_UNIT),
             DISTRIBUTION_AGGREGATION_DESCRIPTOR,
             Arrays.asList(KEY)));
-    MeasurementDescriptor measure2 =
-        MeasurementDescriptor.create(MEASUREMENT_NAME_2, "measurement", MEASUREMENT_UNIT);
+    Measure measure2 =
+        Measure.DoubleMeasure.create(MEASUREMENT_NAME_2, "measurement", MEASUREMENT_UNIT);
     statsRecorder.record(createContext(factory, KEY, VALUE), MeasurementMap.of(measure2, 10.0));
     DistributionView view = (DistributionView) viewManager.getView(VIEW_NAME);
     assertThat(view.getDistributionAggregations()).isEmpty();
@@ -403,10 +398,10 @@ public class ViewManagerImplTest {
 
   @Test
   public void testMultipleViewsDifferentMeasures() {
-    MeasurementDescriptor measureDescr1 =
-        MeasurementDescriptor.create(MEASUREMENT_NAME, MEASUREMENT_DESCRIPTION, MEASUREMENT_UNIT);
-    MeasurementDescriptor measureDescr2 =
-        MeasurementDescriptor.create(MEASUREMENT_NAME_2, MEASUREMENT_DESCRIPTION, MEASUREMENT_UNIT);
+    Measure measureDescr1 =
+        Measure.DoubleMeasure.create(MEASUREMENT_NAME, MEASUREMENT_DESCRIPTION, MEASUREMENT_UNIT);
+    Measure measureDescr2 =
+        Measure.DoubleMeasure.create(MEASUREMENT_NAME_2, MEASUREMENT_DESCRIPTION, MEASUREMENT_UNIT);
     ViewDescriptor viewDescr1 =
         createDistributionViewDescriptor(
             VIEW_NAME, measureDescr1, DISTRIBUTION_AGGREGATION_DESCRIPTOR, Arrays.asList(KEY));
diff --git a/examples/src/main/java/io/opencensus/examples/stats/StatsRunner.java b/examples/src/main/java/io/opencensus/examples/stats/StatsRunner.java
index 86a4e3dc..2595b855 100644
--- a/examples/src/main/java/io/opencensus/examples/stats/StatsRunner.java
+++ b/examples/src/main/java/io/opencensus/examples/stats/StatsRunner.java
@@ -14,16 +14,13 @@
 package io.opencensus.examples.stats;
 
 import io.opencensus.common.NonThrowingCloseable;
-import io.opencensus.stats.MeasurementDescriptor;
-import io.opencensus.stats.MeasurementDescriptor.BasicUnit;
-import io.opencensus.stats.MeasurementDescriptor.MeasurementUnit;
+import io.opencensus.stats.Measure;
 import io.opencensus.stats.MeasurementMap;
 import io.opencensus.stats.Stats;
 import io.opencensus.stats.StatsContext;
 import io.opencensus.stats.StatsContextFactory;
 import io.opencensus.stats.TagKey;
 import io.opencensus.stats.TagValue;
-import java.util.Arrays;
 
 /** Simple program that uses Stats contexts. */
 public class StatsRunner {
@@ -37,12 +34,11 @@ public class StatsRunner {
   private static final TagValue V3 = TagValue.create("v3");
   private static final TagValue V4 = TagValue.create("v4");
 
-  private static final MeasurementUnit simpleMeasurementUnit =
-      MeasurementUnit.create(1, Arrays.asList(BasicUnit.SCALAR));
-  private static final MeasurementDescriptor M1 =
-      MeasurementDescriptor.create("m1", "1st test metric", simpleMeasurementUnit);
-  private static final MeasurementDescriptor M2 =
-      MeasurementDescriptor.create("m2", "2nd test metric", simpleMeasurementUnit);
+  private static final String UNIT = "1";
+  private static final Measure M1 =
+      Measure.DoubleMeasure.create("m1", "1st test metric", UNIT);
+  private static final Measure M2 =
+      Measure.DoubleMeasure.create("m2", "2nd test metric", UNIT);
 
   private static final StatsContextFactory factory = Stats.getStatsContextFactory();
   private static final StatsContext DEFAULT = factory.getDefault();