diff --git a/google-cloud-logging/src/main/java/com/google/cloud/logging/LoggingImpl.java b/google-cloud-logging/src/main/java/com/google/cloud/logging/LoggingImpl.java
index cdfc86c7a8fd..0f427ec6d640 100644
--- a/google-cloud-logging/src/main/java/com/google/cloud/logging/LoggingImpl.java
+++ b/google-cloud-logging/src/main/java/com/google/cloud/logging/LoggingImpl.java
@@ -25,6 +25,7 @@
 import static com.google.cloud.logging.Logging.WriteOption.OptionType.LOG_NAME;
 import static com.google.cloud.logging.Logging.WriteOption.OptionType.RESOURCE;
 
+import com.google.api.gax.core.ApiFunction;
 import com.google.api.gax.core.ApiFuture;
 import com.google.api.gax.core.ApiFutures;
 import com.google.cloud.AsyncPage;
@@ -105,7 +106,7 @@ private static <V> V get(ApiFuture<V> future) {
 
   private static <I, O> ApiFuture<O> transform(ApiFuture<I> future,
       final Function<? super I, ? extends O> function) {
-    return ApiFutures.transform(future, new com.google.api.gax.core.Function<I, O>() {
+    return ApiFutures.transform(future, new ApiFunction<I, O>() {
       @Override
       public O apply(I i) {
         return function.apply(i);
diff --git a/google-cloud-logging/src/main/java/com/google/cloud/logging/spi/v2/GrpcLoggingRpc.java b/google-cloud-logging/src/main/java/com/google/cloud/logging/spi/v2/GrpcLoggingRpc.java
index 31f5c4ef2221..e7b8ddffb2ad 100644
--- a/google-cloud-logging/src/main/java/com/google/cloud/logging/spi/v2/GrpcLoggingRpc.java
+++ b/google-cloud-logging/src/main/java/com/google/cloud/logging/spi/v2/GrpcLoggingRpc.java
@@ -16,9 +16,9 @@
 
 package com.google.cloud.logging.spi.v2;
 
+import com.google.api.gax.core.ApiFunction;
 import com.google.api.gax.core.ApiFuture;
 import com.google.api.gax.core.ApiFutures;
-import com.google.api.gax.core.Function;
 import com.google.api.gax.grpc.ApiException;
 import com.google.api.gax.grpc.ChannelProvider;
 import com.google.api.gax.grpc.ExecutorProvider;
@@ -132,7 +132,7 @@ private static <V> ApiFuture<V> translate(
     return ApiFutures.catching(
         from,
         ApiException.class,
-        new Function<ApiException, V>() {
+        new ApiFunction<ApiException, V>() {
           @Override
           public V apply(ApiException exception) {
             if (returnNullOnSet.contains(exception.getStatusCode())) {
diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/deprecated/PubSubImpl.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/deprecated/PubSubImpl.java
index c74cd4012f5b..2a422c2a4c19 100644
--- a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/deprecated/PubSubImpl.java
+++ b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/deprecated/PubSubImpl.java
@@ -23,6 +23,7 @@
 import static com.google.common.base.MoreObjects.firstNonNull;
 import static com.google.common.base.Preconditions.checkArgument;
 
+import com.google.api.gax.core.ApiFunction;
 import com.google.api.gax.core.ApiFuture;
 import com.google.api.gax.core.ApiFutureCallback;
 import com.google.api.gax.core.ApiFutures;
@@ -203,7 +204,7 @@ private static <V> V get(ApiFuture<V> future) {
 
   private static <I, O> ApiFuture<O> transform(ApiFuture<I> future,
       final Function<? super I, ? extends O> function) {
-    return ApiFutures.transform(future, new com.google.api.gax.core.Function<I, O>() {
+    return ApiFutures.transform(future, new ApiFunction<I, O>() {
       @Override
       public O apply(I i) {
         return function.apply(i);
diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/deprecated/spi/v1/GrpcPubSubRpc.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/deprecated/spi/v1/GrpcPubSubRpc.java
index 1773659381ca..82c96da53b13 100644
--- a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/deprecated/spi/v1/GrpcPubSubRpc.java
+++ b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/deprecated/spi/v1/GrpcPubSubRpc.java
@@ -16,9 +16,9 @@
 
 package com.google.cloud.pubsub.deprecated.spi.v1;
 
+import com.google.api.gax.core.ApiFunction;
 import com.google.api.gax.core.ApiFuture;
 import com.google.api.gax.core.ApiFutures;
-import com.google.api.gax.core.Function;
 import com.google.api.gax.grpc.ApiException;
 import com.google.api.gax.grpc.ChannelProvider;
 import com.google.api.gax.grpc.ExecutorProvider;
@@ -135,7 +135,7 @@ private static <V> ApiFuture<V> translate(
     return ApiFutures.<V, ApiException>catching(
         from,
         ApiException.class,
-        new Function<ApiException, V>() {
+        new ApiFunction<ApiException, V>() {
           @Override
           public V apply(ApiException exception) {
             if (returnNullOnSet.contains(exception.getStatusCode().value())) {
diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/SubscriberClient.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/SubscriberClient.java
index 3a0883e85b7f..6f7f802fcbc6 100644
--- a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/SubscriberClient.java
+++ b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/SubscriberClient.java
@@ -897,8 +897,8 @@ public final UnaryCallable<PullRequest, PullResponse> pullCallable() {
    *
    * <pre><code>
    * try (SubscriberClient subscriberClient = SubscriberClient.create()) {
-   *   RpcStreamObserver&lt;StreamingPullResponse&gt; responseObserver =
-   *       new RpcStreamObserver&lt;StreamingPullResponse&gt;() {
+   *   ApiStreamObserver&lt;StreamingPullResponse&gt; responseObserver =
+   *       new ApiStreamObserver&lt;StreamingPullResponse&gt;() {
    *         {@literal @}Override
    *         public void onNext(StreamingPullResponse response) {
    *           // Do something when receive a response
@@ -914,7 +914,7 @@ public final UnaryCallable<PullRequest, PullResponse> pullCallable() {
    *           // Do something when complete.
    *         }
    *       };
-   *   RpcStreamObserver&lt;StreamingRecognizeRequest&gt; requestObserver =
+   *   ApiStreamObserver&lt;StreamingRecognizeRequest&gt; requestObserver =
    *       subscriberClient.streamingPullCallable().bidiStreamingCall(responseObserver)});
    *
    *   SubscriptionName subscription = SubscriptionName.create("[PROJECT]", "[SUBSCRIPTION]");
diff --git a/google-cloud-pubsub/src/test/java/com/google/cloud/pubsub/spi/v1/SubscriberClientTest.java b/google-cloud-pubsub/src/test/java/com/google/cloud/pubsub/spi/v1/SubscriberClientTest.java
index 265168dabb65..36f9901abc62 100644
--- a/google-cloud-pubsub/src/test/java/com/google/cloud/pubsub/spi/v1/SubscriberClientTest.java
+++ b/google-cloud-pubsub/src/test/java/com/google/cloud/pubsub/spi/v1/SubscriberClientTest.java
@@ -17,7 +17,7 @@
 
 import static com.google.cloud.pubsub.spi.v1.PagedResponseWrappers.ListSubscriptionsPagedResponse;
 
-import com.google.api.gax.core.RpcStreamObserver;
+import com.google.api.gax.core.ApiStreamObserver;
 import com.google.api.gax.grpc.ApiException;
 import com.google.api.gax.grpc.StreamingCallable;
 import com.google.api.gax.testing.MockGrpcService;
@@ -406,7 +406,7 @@ public void streamingPullTest() throws Exception {
 
     StreamingCallable<StreamingPullRequest, StreamingPullResponse> callable =
         client.streamingPullCallable();
-    RpcStreamObserver<StreamingPullRequest> requestObserver =
+    ApiStreamObserver<StreamingPullRequest> requestObserver =
         callable.bidiStreamingCall(responseObserver);
 
     requestObserver.onNext(request);
@@ -434,7 +434,7 @@ public void streamingPullExceptionTest() throws Exception {
 
     StreamingCallable<StreamingPullRequest, StreamingPullResponse> callable =
         client.streamingPullCallable();
-    RpcStreamObserver<StreamingPullRequest> requestObserver =
+    ApiStreamObserver<StreamingPullRequest> requestObserver =
         callable.bidiStreamingCall(responseObserver);
 
     requestObserver.onNext(request);
diff --git a/google-cloud-speech/src/main/java/com/google/cloud/speech/spi/v1beta1/SpeechClient.java b/google-cloud-speech/src/main/java/com/google/cloud/speech/spi/v1beta1/SpeechClient.java
index 1c66cf54bd27..6da697beaccb 100644
--- a/google-cloud-speech/src/main/java/com/google/cloud/speech/spi/v1beta1/SpeechClient.java
+++ b/google-cloud-speech/src/main/java/com/google/cloud/speech/spi/v1beta1/SpeechClient.java
@@ -453,8 +453,8 @@ public final UnaryCallable<AsyncRecognizeRequest, Operation> asyncRecognizeCalla
    *
    * <pre><code>
    * try (SpeechClient speechClient = SpeechClient.create()) {
-   *   RpcStreamObserver&lt;StreamingRecognizeResponse&gt; responseObserver =
-   *       new RpcStreamObserver&lt;StreamingRecognizeResponse&gt;() {
+   *   ApiStreamObserver&lt;StreamingRecognizeResponse&gt; responseObserver =
+   *       new ApiStreamObserver&lt;StreamingRecognizeResponse&gt;() {
    *         {@literal @}Override
    *         public void onNext(StreamingRecognizeResponse response) {
    *           // Do something when receive a response
@@ -470,7 +470,7 @@ public final UnaryCallable<AsyncRecognizeRequest, Operation> asyncRecognizeCalla
    *           // Do something when complete.
    *         }
    *       };
-   *   RpcStreamObserver&lt;StreamingRecognizeRequest&gt; requestObserver =
+   *   ApiStreamObserver&lt;StreamingRecognizeRequest&gt; requestObserver =
    *       speechClient.streamingRecognizeCallable().bidiStreamingCall(responseObserver)});
    *
    *   StreamingRecognizeRequest request = StreamingRecognizeRequest.newBuilder().build();
diff --git a/google-cloud-speech/src/test/java/com/google/cloud/speech/spi/v1beta1/SpeechClientTest.java b/google-cloud-speech/src/test/java/com/google/cloud/speech/spi/v1beta1/SpeechClientTest.java
index f455c4db6aff..d98938f1967b 100644
--- a/google-cloud-speech/src/test/java/com/google/cloud/speech/spi/v1beta1/SpeechClientTest.java
+++ b/google-cloud-speech/src/test/java/com/google/cloud/speech/spi/v1beta1/SpeechClientTest.java
@@ -15,7 +15,7 @@
  */
 package com.google.cloud.speech.spi.v1beta1;
 
-import com.google.api.gax.core.RpcStreamObserver;
+import com.google.api.gax.core.ApiStreamObserver;
 import com.google.api.gax.grpc.ApiException;
 import com.google.api.gax.grpc.StreamingCallable;
 import com.google.api.gax.testing.MockGrpcService;
@@ -191,7 +191,7 @@ public void streamingRecognizeTest() throws Exception {
 
     StreamingCallable<StreamingRecognizeRequest, StreamingRecognizeResponse> callable =
         client.streamingRecognizeCallable();
-    RpcStreamObserver<StreamingRecognizeRequest> requestObserver =
+    ApiStreamObserver<StreamingRecognizeRequest> requestObserver =
         callable.bidiStreamingCall(responseObserver);
 
     requestObserver.onNext(request);
@@ -213,7 +213,7 @@ public void streamingRecognizeExceptionTest() throws Exception {
 
     StreamingCallable<StreamingRecognizeRequest, StreamingRecognizeResponse> callable =
         client.streamingRecognizeCallable();
-    RpcStreamObserver<StreamingRecognizeRequest> requestObserver =
+    ApiStreamObserver<StreamingRecognizeRequest> requestObserver =
         callable.bidiStreamingCall(responseObserver);
 
     requestObserver.onNext(request);
diff --git a/pom.xml b/pom.xml
index 1fb6e12d0ac1..1d0e44083488 100644
--- a/pom.xml
+++ b/pom.xml
@@ -92,7 +92,7 @@
     <github.global.server>github</github.global.server>
     <google.auth.version>0.6.0</google.auth.version>
     <grpc.version>1.0.3</grpc.version>
-    <gax.version>0.5.0</gax.version>
+    <gax.version>0.6.0</gax.version>
     <generatedProto.version>0.1.5</generatedProto.version>
     <core.version>0.10.1-alpha-SNAPSHOT</core.version>
     <beta.version>0.10.1-beta-SNAPSHOT</beta.version>