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diff --git a/api/src/main/java/io/opencensus/trace/AttributeValue.java b/api/src/main/java/io/opencensus/trace/AttributeValue.java
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+++ b/api/src/main/java/io/opencensus/trace/AttributeValue.java
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+/*
+ * Copyright 2016-17, OpenCensus Authors
+ *
+ * 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.trace;
+
+import com.google.auto.value.AutoValue;
+import io.opencensus.common.Function;
+import io.opencensus.internal.Utils;
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * A class that represents all the possible values for an attribute. An attribute can have 3 types
+ * of values: {@code String}, {@code Boolean} or {@code Long}.
+ *
+ * @since 0.5
+ */
+@Immutable
+public abstract class AttributeValue {
+  /**
+   * Returns an {@code AttributeValue} with a string value.
+   *
+   * @param stringValue The new value.
+   * @return an {@code AttributeValue} with a string value.
+   * @throws NullPointerException if {@code stringValue} is {@code null}.
+   * @since 0.5
+   */
+  public static AttributeValue stringAttributeValue(String stringValue) {
+    return AttributeValueString.create(stringValue);
+  }
+
+  /**
+   * Returns an {@code AttributeValue} with a boolean value.
+   *
+   * @param booleanValue The new value.
+   * @return an {@code AttributeValue} with a boolean value.
+   * @since 0.5
+   */
+  public static AttributeValue booleanAttributeValue(boolean booleanValue) {
+    return AttributeValueBoolean.create(booleanValue);
+  }
+
+  /**
+   * Returns an {@code AttributeValue} with a long value.
+   *
+   * @param longValue The new value.
+   * @return an {@code AttributeValue} with a long value.
+   * @since 0.5
+   */
+  public static AttributeValue longAttributeValue(long longValue) {
+    return AttributeValueLong.create(longValue);
+  }
+
+  /**
+   * Returns an {@code AttributeValue} with a double value.
+   *
+   * @param doubleValue The new value.
+   * @return an {@code AttributeValue} with a double value.
+   * @since 0.17
+   */
+  public static AttributeValue doubleAttributeValue(double doubleValue) {
+    return AttributeValueDouble.create(doubleValue);
+  }
+
+  AttributeValue() {}
+
+  /**
+   * Applies a function to the underlying value. The function that is called depends on the value's
+   * type, which can be {@code String}, {@code Long}, or {@code Boolean}.
+   *
+   * @param stringFunction the function that should be applied if the value has type {@code String}.
+   * @param longFunction the function that should be applied if the value has type {@code Long}.
+   * @param booleanFunction the function that should be applied if the value has type {@code
+   *     Boolean}.
+   * @param defaultFunction the function that should be applied if the value has a type that was
+   *     added after this {@code match} method was added to the API. See {@link
+   *     io.opencensus.common.Functions} for some common functions for handling unknown types.
+   * @return the result of the function applied to the underlying value.
+   * @since 0.5
+   * @deprecated in favor of {@link #match(Function, Function, Function, Function, Function)}.
+   */
+  @Deprecated
+  public abstract <T> T match(
+      Function<? super String, T> stringFunction,
+      Function<? super Boolean, T> booleanFunction,
+      Function<? super Long, T> longFunction,
+      Function<Object, T> defaultFunction);
+
+  /**
+   * Applies a function to the underlying value. The function that is called depends on the value's
+   * type, which can be {@code String}, {@code Long}, or {@code Boolean}.
+   *
+   * @param stringFunction the function that should be applied if the value has type {@code String}.
+   * @param longFunction the function that should be applied if the value has type {@code Long}.
+   * @param booleanFunction the function that should be applied if the value has type {@code
+   *     Boolean}.
+   * @param doubleFunction the function that should be applied if the value has type {@code Double}.
+   * @param defaultFunction the function that should be applied if the value has a type that was
+   *     added after this {@code match} method was added to the API. See {@link
+   *     io.opencensus.common.Functions} for some common functions for handling unknown types.
+   * @return the result of the function applied to the underlying value.
+   * @since 0.17
+   */
+  @SuppressWarnings("InconsistentOverloads")
+  public abstract <T> T match(
+      Function<? super String, T> stringFunction,
+      Function<? super Boolean, T> booleanFunction,
+      Function<? super Long, T> longFunction,
+      Function<? super Double, T> doubleFunction,
+      Function<Object, T> defaultFunction);
+
+  @Immutable
+  @AutoValue
+  abstract static class AttributeValueString extends AttributeValue {
+
+    AttributeValueString() {}
+
+    static AttributeValue create(String stringValue) {
+      return new AutoValue_AttributeValue_AttributeValueString(
+          Utils.checkNotNull(stringValue, "stringValue"));
+    }
+
+    @Override
+    public final <T> T match(
+        Function<? super String, T> stringFunction,
+        Function<? super Boolean, T> booleanFunction,
+        Function<? super Long, T> longFunction,
+        Function<Object, T> defaultFunction) {
+      return stringFunction.apply(getStringValue());
+    }
+
+    @Override
+    public final <T> T match(
+        Function<? super String, T> stringFunction,
+        Function<? super Boolean, T> booleanFunction,
+        Function<? super Long, T> longFunction,
+        Function<? super Double, T> doubleFunction,
+        Function<Object, T> defaultFunction) {
+      return stringFunction.apply(getStringValue());
+    }
+
+    abstract String getStringValue();
+  }
+
+  @Immutable
+  @AutoValue
+  abstract static class AttributeValueBoolean extends AttributeValue {
+
+    AttributeValueBoolean() {}
+
+    static AttributeValue create(Boolean booleanValue) {
+      return new AutoValue_AttributeValue_AttributeValueBoolean(
+          Utils.checkNotNull(booleanValue, "booleanValue"));
+    }
+
+    @Override
+    public final <T> T match(
+        Function<? super String, T> stringFunction,
+        Function<? super Boolean, T> booleanFunction,
+        Function<? super Long, T> longFunction,
+        Function<Object, T> defaultFunction) {
+      return booleanFunction.apply(getBooleanValue());
+    }
+
+    @Override
+    public final <T> T match(
+        Function<? super String, T> stringFunction,
+        Function<? super Boolean, T> booleanFunction,
+        Function<? super Long, T> longFunction,
+        Function<? super Double, T> doubleFunction,
+        Function<Object, T> defaultFunction) {
+      return booleanFunction.apply(getBooleanValue());
+    }
+
+    abstract Boolean getBooleanValue();
+  }
+
+  @Immutable
+  @AutoValue
+  abstract static class AttributeValueLong extends AttributeValue {
+
+    AttributeValueLong() {}
+
+    static AttributeValue create(Long longValue) {
+      return new AutoValue_AttributeValue_AttributeValueLong(
+          Utils.checkNotNull(longValue, "longValue"));
+    }
+
+    @Override
+    public final <T> T match(
+        Function<? super String, T> stringFunction,
+        Function<? super Boolean, T> booleanFunction,
+        Function<? super Long, T> longFunction,
+        Function<Object, T> defaultFunction) {
+      return longFunction.apply(getLongValue());
+    }
+
+    @Override
+    public final <T> T match(
+        Function<? super String, T> stringFunction,
+        Function<? super Boolean, T> booleanFunction,
+        Function<? super Long, T> longFunction,
+        Function<? super Double, T> doubleFunction,
+        Function<Object, T> defaultFunction) {
+      return longFunction.apply(getLongValue());
+    }
+
+    abstract Long getLongValue();
+  }
+
+  @Immutable
+  @AutoValue
+  abstract static class AttributeValueDouble extends AttributeValue {
+
+    AttributeValueDouble() {}
+
+    static AttributeValue create(Double doubleValue) {
+      return new AutoValue_AttributeValue_AttributeValueDouble(
+          Utils.checkNotNull(doubleValue, "doubleValue"));
+    }
+
+    @Override
+    public final <T> T match(
+        Function<? super String, T> stringFunction,
+        Function<? super Boolean, T> booleanFunction,
+        Function<? super Long, T> longFunction,
+        Function<Object, T> defaultFunction) {
+      return defaultFunction.apply(getDoubleValue());
+    }
+
+    @Override
+    public final <T> T match(
+        Function<? super String, T> stringFunction,
+        Function<? super Boolean, T> booleanFunction,
+        Function<? super Long, T> longFunction,
+        Function<? super Double, T> doubleFunction,
+        Function<Object, T> defaultFunction) {
+      return doubleFunction.apply(getDoubleValue());
+    }
+
+    abstract Double getDoubleValue();
+  }
+}