Address review comments

Author: vkedia

spanner/cloud-client/README.md

@@ -31,5 +31,11 @@ You can then run a given `ClassName` via:
 ### Running the tutorial
     mvn exec:java -Dexec.mainClass=com.example.spanner.SpannerSample -Dexec.args="<command> my-instance my-database"
 
+## Tracing sample
+TracingSample.java demonstrates how to export traces generated by client library to StackDriver and to /tracez page.
+
+### Running the tracing sample
+    mvn exec:java -Dexec.mainClass=com.example.spanner.TracingSample -Dexec.args="my-instance my-database"
+
 ## Test
     mvn verify -Dspanner.test.instance=<instance id> -Dspanner.sample.database=<new database id>  -Dspanner.quickstart.database=<existing database id>

spanner/cloud-client/pom.xml

@@ -46,6 +46,7 @@ limitations under the License.
     <maven.compiler.target>1.8</maven.compiler.target>
     <maven.compiler.source>1.8</maven.compiler.source>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <opencensus.version>0.11.0</opencensus.version>
   </properties>
 
   <dependencies>
@@ -73,27 +74,33 @@ limitations under the License.
     <dependency>
         <groupId>io.opencensus</groupId>
         <artifactId>opencensus-api</artifactId>
-        <version>0.11.0</version>
+        <version>${opencensus.version}</version>
     </dependency>
     <dependency>
         <groupId>io.opencensus</groupId>
         <artifactId>opencensus-impl</artifactId>
-        <version>0.11.0</version>
+        <version>${opencensus.version}</version>
+        <scope>runtime</scope>
     </dependency>
     <dependency>
         <groupId>io.opencensus</groupId>
         <artifactId>opencensus-contrib-zpages</artifactId>
-        <version>0.11.0</version>
+        <version>${opencensus.version}</version>
     </dependency>
     <dependency>
         <groupId>io.opencensus</groupId>
-        <artifactId>opencensus-exporter-trace-logging</artifactId>
-        <version>0.11.0</version>
+        <artifactId>opencensus-exporter-trace-stackdriver</artifactId>
+        <version>${opencensus.version}</version>
     </dependency>
     <dependency>
         <groupId>io.opencensus</groupId>
-        <artifactId>opencensus-exporter-trace-stackdriver</artifactId>
-        <version>0.11.0</version>
+        <artifactId>opencensus-exporter-stats-stackdriver</artifactId>
+        <version>${opencensus.version}</version>
+    </dependency>
+    <dependency>
+        <groupId>io.opencensus</groupId>
+        <artifactId>opencensus-contrib-grpc-metrics</artifactId>
+        <version>${opencensus.version}</version>
     </dependency>
 
     <!-- Test dependencies -->

spanner/cloud-client/src/main/java/com/example/spanner/TracingSample.java

@@ -10,12 +10,16 @@
 import com.google.cloud.spanner.Statement;
 
 import io.opencensus.common.Scope;
+import io.opencensus.contrib.grpc.metrics.RpcViews;
 import io.opencensus.contrib.zpages.ZPageHandlers;
+import io.opencensus.exporter.stats.stackdriver.StackdriverStatsExporter;
 import io.opencensus.exporter.trace.stackdriver.StackdriverExporter;
 import io.opencensus.trace.Tracing;
 import io.opencensus.trace.samplers.Samplers;
 
 public class TracingSample {
+  
+  private static final String SAMPLE_SPAN = "CloudSpannerSample";
 
   public static void main(String[] args) throws Exception {	
     if (args.length != 2) {
@@ -27,10 +31,14 @@ public static void main(String[] args) throws Exception {
 
     // Installs a handler for /tracez page.
     ZPageHandlers.startHttpServerAndRegisterAll(8080);
-    // Installs an exporter for stack driver.
+    // Installs an exporter for stack driver traces.
     StackdriverExporter.createAndRegister();
-    Tracing.getExportComponent().getSampledSpanStore().registerSpanNamesForCollection(Arrays.asList("CloudSpannerSample"));
+    Tracing.getExportComponent().getSampledSpanStore().registerSpanNamesForCollection(Arrays.asList(SAMPLE_SPAN));
 
+    // Installs an exporter for stack driver stats.
+    StackdriverStatsExporter.createAndRegister();
+    RpcViews.registerAllCumulativeViews();
+    
     // Name of your instance & database.
     String instanceId = args[0];
     String databaseId = args[1];
@@ -40,7 +48,7 @@ public static void main(String[] args) throws Exception {
           options.getProjectId(), instanceId, databaseId));
       // Queries the database
       try (Scope ss = Tracing.getTracer()
-          .spanBuilderWithExplicitParent("CloudSpannerSample", null)
+          .spanBuilderWithExplicitParent(SAMPLE_SPAN, null)
           .setSampler(Samplers.alwaysSample())
           .startScopedSpan()) {
         ResultSet resultSet = dbClient.singleUse().executeQuery(Statement.of("SELECT 1"));