diff --git a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroup.java b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroup.java
index 3ad514d938..75722a494f 100644
--- a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroup.java
+++ b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroup.java
@@ -7,8 +7,7 @@
 
 package com.microsoft.azure;
 
-import com.microsoft.rest.ServiceCall;
-import com.microsoft.rest.ServiceCallback;
+import rx.Observable;
 
 /**
  * Represents a group of related tasks.
@@ -60,10 +59,9 @@ public interface TaskGroup<T, U extends TaskItem<T>> {
     /**
      * Executes the tasks in the group asynchronously.
      *
-     * @param callback the callback to call on failure or success
      * @return the handle to the REST call
      */
-    ServiceCall executeAsync(ServiceCallback<T> callback);
+    Observable<T> executeAsync();
 
     /**
      * Gets the result of execution of a task in the group.
diff --git a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroupBase.java b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroupBase.java
index 5078b8caa6..d670876e10 100644
--- a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroupBase.java
+++ b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroupBase.java
@@ -7,11 +7,11 @@
 
 package com.microsoft.azure;
 
-import com.microsoft.rest.ServiceCall;
-import com.microsoft.rest.ServiceCallback;
-import com.microsoft.rest.ServiceResponse;
+import rx.Observable;
+import rx.functions.Func1;
 
-import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.ArrayList;
+import java.util.List;
 
 /**
  * The base implementation of TaskGroup interface.
@@ -22,7 +22,6 @@
 public abstract class TaskGroupBase<T, U extends TaskItem<T>>
     implements TaskGroup<T, U> {
     private DAGraph<U, DAGNode<U>> dag;
-    private ParallelServiceCall parallelServiceCall;
 
     /**
      * Creates TaskGroupBase.
@@ -32,7 +31,6 @@ public abstract class TaskGroupBase<T, U extends TaskItem<T>>
      */
     public TaskGroupBase(String rootTaskItemId, U rootTaskItem) {
         this.dag = new DAGraph<>(new DAGNode<>(rootTaskItemId, rootTaskItem));
-        this.parallelServiceCall = new ParallelServiceCall();
     }
 
     @Override
@@ -68,9 +66,8 @@ public void execute() throws Exception {
     }
 
     @Override
-    public ServiceCall<T> executeAsync(final ServiceCallback<T> callback) {
-        executeReadyTasksAsync(callback);
-        return parallelServiceCall;
+    public Observable<T> executeAsync() {
+        return executeReadyTasksAsync();
     }
 
     @Override
@@ -81,92 +78,26 @@ public T taskResult(String taskId) {
     /**
      * Executes all runnable tasks, a task is runnable when all the tasks its depends
      * on are finished running.
-     *
-     * @param callback the callback
      */
-    private void executeReadyTasksAsync(final ServiceCallback<T> callback) {
+    private Observable<T> executeReadyTasksAsync() {
         DAGNode<U> nextNode = dag.getNext();
+        final List<Observable<T>> observables = new ArrayList<>();
         while (nextNode != null) {
-            ServiceCall serviceCall = nextNode.data().executeAsync(taskCallback(nextNode, callback));
-            this.parallelServiceCall.addCall(serviceCall);
+            final DAGNode<U> thisNode = nextNode;
+            observables.add(nextNode.data().executeAsync()
+                    .flatMap(new Func1<T, Observable<T>>() {
+                        @Override
+                        public Observable<T> call(T t) {
+                            dag().reportedCompleted(thisNode);
+                            if (dag().isRootNode(thisNode)) {
+                                return Observable.just(t);
+                            } else {
+                                return executeReadyTasksAsync();
+                            }
+                        }
+                    }));
             nextNode = dag.getNext();
         }
-    }
-
-    /**
-     * This method create and return a callback for the runnable task stored in the given node.
-     * This callback wraps the given callback.
-     *
-     * @param taskNode the node containing runnable task
-     * @param callback the callback to wrap
-     * @return the task callback
-     */
-    private ServiceCallback<T> taskCallback(final DAGNode<U> taskNode, final ServiceCallback<T> callback) {
-        final TaskGroupBase<T, U> self = this;
-        return new ServiceCallback<T>() {
-            @Override
-            public void failure(Throwable t) {
-                callback.failure(t);
-                parallelServiceCall.failure(t);
-            }
-
-            @Override
-            public void success(ServiceResponse<T> result) {
-                self.dag().reportedCompleted(taskNode);
-                if (self.dag().isRootNode(taskNode)) {
-                    if (callback != null) {
-                        callback.success(result);
-                    }
-                    parallelServiceCall.success(result);
-                } else {
-                    self.executeReadyTasksAsync(callback);
-                }
-            }
-        };
-    }
-
-    /**
-     * Type represents a set of REST calls running possibly in parallel.
-     */
-    private class ParallelServiceCall extends ServiceCall<T> {
-        private ConcurrentLinkedQueue<ServiceCall<?>> serviceCalls;
-
-        /**
-         * Creates a ParallelServiceCall.
-         */
-        ParallelServiceCall() {
-            super(null);
-            this.serviceCalls = new ConcurrentLinkedQueue<>();
-        }
-
-        /**
-         * Cancels all the service calls currently executing.
-         */
-        public void cancel() {
-            for (ServiceCall<?> call : this.serviceCalls) {
-                call.cancel(true);
-            }
-        }
-
-        /**
-         * @return true if the call has been canceled; false otherwise.
-         */
-        public boolean isCancelled() {
-            for (ServiceCall<?> call : this.serviceCalls) {
-                if (!call.isCancelled()) {
-                    return false;
-                }
-            }
-            return true;
-        }
-
-        /**
-         * Add a call to the list of parallel calls.
-         *
-         * @param call the call
-         */
-        private void addCall(ServiceCall<?> call) {
-            this.serviceCalls.add(call);
-        }
+        return Observable.merge(observables).last();
     }
 }
diff --git a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskItem.java b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskItem.java
index 8f0a3459a2..df9bf4b04a 100644
--- a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskItem.java
+++ b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskItem.java
@@ -7,8 +7,7 @@
 
 package com.microsoft.azure;
 
-import com.microsoft.rest.ServiceCall;
-import com.microsoft.rest.ServiceCallback;
+import rx.Observable;
 
 /**
  * Type representing a task in a task group {@link TaskGroup}.
@@ -35,8 +34,7 @@ public interface TaskItem<U> {
      * <p>
      * once executed the result will be available through result getter
      *
-     * @param callback callback to call on success or failure
      * @return the handle of the REST call
      */
-    ServiceCall executeAsync(ServiceCallback<U> callback);
+    Observable<U> executeAsync();
 }
diff --git a/build-tools/src/main/resources/checkstyle.xml b/build-tools/src/main/resources/checkstyle.xml
index b7f9348982..d382291b82 100644
--- a/build-tools/src/main/resources/checkstyle.xml
+++ b/build-tools/src/main/resources/checkstyle.xml
@@ -79,11 +79,6 @@
         <property name="eachLine" value="true"/>
     </module>
 
-    <module name="RegexpSingleline">
-        <property name="format" value="\s+$"/>
-        <property name="message" value="Line has trailing spaces."/>
-    </module>
-
     <module name="TreeWalker">
         <!-- Checks for Javadoc comments.                     -->
         <!-- See http://checkstyle.sf.net/config_javadoc.html -->
diff --git a/client-runtime/pom.xml b/client-runtime/pom.xml
index e63a421434..d904227d91 100644
--- a/client-runtime/pom.xml
+++ b/client-runtime/pom.xml
@@ -79,6 +79,10 @@
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-lang3</artifactId>
     </dependency>
+    <dependency>
+      <groupId>io.reactivex</groupId>
+      <artifactId>rxjava</artifactId>
+    </dependency>
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
diff --git a/client-runtime/src/main/java/com/microsoft/rest/ServiceCall.java b/client-runtime/src/main/java/com/microsoft/rest/ServiceCall.java
index c0cb3b62eb..1baf40cbd9 100644
--- a/client-runtime/src/main/java/com/microsoft/rest/ServiceCall.java
+++ b/client-runtime/src/main/java/com/microsoft/rest/ServiceCall.java
@@ -10,6 +10,9 @@
 import com.google.common.util.concurrent.AbstractFuture;
 
 import retrofit2.Call;
+import rx.Observable;
+import rx.Scheduler;
+import rx.functions.Func1;
 
 /**
  * An instance of this class provides access to the underlying REST call invocation.
@@ -72,6 +75,31 @@ public boolean isCancelled() {
         return call.isCanceled();
     }
 
+    /**
+     * Get an RxJava Observable object for the response.
+     *
+     * @return the Observable
+     */
+    public Observable<T> observable() {
+        return Observable.from(this)
+                .map(new Func1<ServiceResponse<T>, T>() {
+                    @Override
+                    public T call(ServiceResponse<T> tServiceResponse) {
+                        return tServiceResponse.getBody();
+                    }
+                });
+    }
+
+    /**
+     * Get an RxJava Observable object for the response bound on a scheduler.
+     *
+     * @param scheduler the scheduler to bind to
+     * @return the Observable
+     */
+    public Observable<T> observable(Scheduler scheduler) {
+        return observable().subscribeOn(scheduler);
+    }
+
     /**
      * Invoke this method to report completed, allowing
      * {@link AbstractFuture#get()} to be unblocked.
diff --git a/pom.xml b/pom.xml
index aa77260c58..082e2e5bfe 100644
--- a/pom.xml
+++ b/pom.xml
@@ -121,6 +121,11 @@
         <artifactId>adal</artifactId>
         <version>1.1.11</version>
       </dependency>
+      <dependency>
+        <groupId>io.reactivex</groupId>
+        <artifactId>rxjava</artifactId>
+        <version>1.1.8</version>
+      </dependency>
       <dependency>
         <groupId>junit</groupId>
         <artifactId>junit</artifactId>