Added example module for zipkin trace exporter (#1383)

* Add example module for Zipkin

* Updated to include Zipkin example module

* Changed to use shutdown() on TracerSdkProvider

* Changed zipkin example module to use shutdown() on TracerSdkProvider

examples/settings.gradle

@@ -16,7 +16,8 @@ include ":opentelemetry-examples-grpc",
         ":opentelemetry-examples-http",
         ":opentelemetry-examples-jaeger",
         ":opentelemetry-examples-metrics",
-        ":opentelemetry-examples-sdk-usage"
+        ":opentelemetry-examples-sdk-usage",
+        ":opentelemetry-examples-zipkin"
 
 rootProject.children.each {
     it.projectDir = "$rootDir/" + it.name

examples/zipkin/README.md

@@ -0,0 +1,32 @@
+# Zipkin Example
+
+This is a simple example that demonstrates how to use the OpenTelemetry SDK 
+to instrument a simple application using Zipkin as trace exporter. 
+
+# How to run
+
+## Prerequisites
+* Java 1.8.231
+* Docker 19.03
+
+## 1 - Compile 
+```shell script
+../gradlew fatJar
+```
+## 2 - Run Zipkin
+
+```shell script
+docker run --rm -it --name zipkin \
+  -p 9411:9411 \
+  openzipkin/zipkin:2.21
+```
+
+## 3 - Start the Application
+```shell script
+java -cp build/libs/opentelemetry-examples-zipkin-all-0.1.0-SNAPSHOT.jar io.opentelemetry.example.ZipkinExample localhost 9411
+```
+## 4 - Open the Zipkin UI
+
+Navigate to http://localhost:9411/zipkin and click on search.
+
+[zipkin]:[https://zipkin.io/]

examples/zipkin/build.gradle

@@ -0,0 +1,12 @@
+plugins {
+    id 'java'
+}
+
+description = 'OpenTelemetry Examples for Zipkin Exporter'
+ext.moduleName = "io.opentelemetry.examples.zipkin"
+
+dependencies {
+    compile("io.opentelemetry:opentelemetry-api:${opentelemetryVersion}")
+    compile("io.opentelemetry:opentelemetry-sdk:${opentelemetryVersion}")
+    compile("io.opentelemetry:opentelemetry-exporters-zipkin:${opentelemetryVersion}")
+}

examples/zipkin/src/main/java/io/opentelemetry/example/ZipkinExample.java

@@ -0,0 +1,91 @@
+package io.opentelemetry.example;
+
+import io.opentelemetry.OpenTelemetry;
+import io.opentelemetry.exporters.zipkin.ZipkinSpanExporter;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.trace.export.SimpleSpanProcessor;
+import io.opentelemetry.trace.Span;
+import io.opentelemetry.trace.Tracer;
+
+public class ZipkinExample {
+
+  // Zipkin Hostname or ip and PORT
+  private String ip; // hostname or ip of the zipkin backend server
+  private int port; // port of the zipkin backend server
+
+  // Zipkin API Endpoints for uploading spans
+  private static final String ENDPOINT_V1_SPANS = "/api/v1/spans";
+  private static final String ENDPOINT_V2_SPANS = "/api/v2/spans";
+
+  // Name of the service
+  private static final String SERVICE_NAME = "myExampleService";
+
+  private Tracer tracer = OpenTelemetry.getTracer("io.opentelemetry.example.ZipkinExample");
+  private ZipkinSpanExporter zipkinExporter;
+
+  public ZipkinExample(String ip, int port) {
+    this.ip = ip;
+    this.port = port;
+  }
+
+  // This method adds SimpleSpanProcessor initialized with ZipkinSpanExporter to the
+  // TracerSdkProvider
+  public void setupZipkinExporter() {
+    String httpUrl = String.format("http://%s:%s", ip, port);
+    this.zipkinExporter =
+        ZipkinSpanExporter.newBuilder()
+            .setEndpoint(httpUrl + ENDPOINT_V2_SPANS)
+            .setServiceName(SERVICE_NAME)
+            .build();
+
+    // Set to process the spans by the Zipkin Exporter
+    OpenTelemetrySdk.getTracerProvider()
+        .addSpanProcessor(SimpleSpanProcessor.newBuilder(zipkinExporter).build());
+  }
+
+  // This method instruments doWork() method
+  public void myWonderfulUseCase() {
+    // Generate span
+    Span span = tracer.spanBuilder("Start my wonderful use case").startSpan();
+    // Add some Event to the span
+    span.addEvent("Event 0");
+    // execute my use case - here we simulate a wait
+    doWork();
+    // Add some Event to the span
+    span.addEvent("Event 1");
+    span.end();
+  }
+
+  public void doWork() {
+    try {
+      Thread.sleep(1000);
+    } catch (InterruptedException e) {
+    }
+  }
+
+  // graceful shutdown
+  public void shutdown() {
+    OpenTelemetrySdk.getTracerProvider().shutdown();
+  }
+
+  public static void main(String[] args) {
+    // Parsing the input
+    if (args.length < 2) {
+      System.out.println("Missing [hostname] [port]");
+      System.exit(1);
+    }
+
+    String ip = args[0];
+    int port = Integer.parseInt(args[1]);
+
+    // start example
+    ZipkinExample example = new ZipkinExample(ip, port);
+    example.setupZipkinExporter();
+    example.myWonderfulUseCase();
+
+    // shutdown example
+    example.shutdown();
+
+    System.out.println("Bye");
+  }
+}