examples(tracing): add multi exporter example (#537)

* docs: add multi exporter example

* chore: add script and update readme

examples/basic-tracer-node/README.md

@@ -57,6 +57,17 @@ Click on the trace to view its details.
 
 <p align="center"><img src="./images/jaeger-ui-detail.png?raw=true"/></p>
 
+### Export to multiple exporters
+
+ - Run the sample
+
+   ```sh
+   $ # from this directory
+   $ npm run multi_exporter
+   ```
+
+   This will export the spans data simultaneously on `Zipkin` and `Jaeger` backend. This is handy if transitioning from one vendor/OSS project to another for the tracing backend. You might want to export to both during the transitional phase.
+
 ## Useful links
 - For more information on OpenTelemetry, visit: <https://opentelemetry.io/>
 - For more information on tracing, visit: <https://github.com/open-telemetry/opentelemetry-js/tree/master/packages/opentelemetry-tracing>

examples/basic-tracer-node/multi_exporter.js

@@ -0,0 +1,55 @@
+const opentelemetry = require('@opentelemetry/core');
+const { BasicTracer, BatchSpanProcessor, SimpleSpanProcessor } = require('@opentelemetry/tracing');
+const { JaegerExporter } = require('@opentelemetry/exporter-jaeger');
+const { ZipkinExporter } = require('@opentelemetry/exporter-zipkin');
+
+const tracer = new BasicTracer();
+
+const zipkinExporter = new ZipkinExporter({serviceName: 'basic-service'});
+const jaegerExporter = new JaegerExporter({
+  serviceName: 'basic-service',
+  // The default flush interval is 5 seconds.
+  flushInterval: 2000
+})
+
+// It is recommended to use this BatchSpanProcessor for better performance
+// and optimization, especially in production.
+tracer.addSpanProcessor(new BatchSpanProcessor(zipkinExporter, {
+  bufferSize: 10 // This is added for example, default size is 100.
+}));
+
+// It is recommended to use SimpleSpanProcessor in case of Jaeger exporter as
+// it's internal client already handles the spans with batching logic.
+tracer.addSpanProcessor(new SimpleSpanProcessor(jaegerExporter));
+
+// Initialize the OpenTelemetry APIs to use the BasicTracer bindings
+opentelemetry.initGlobalTracer(tracer);
+
+// Create a span. A span must be closed.
+const span = opentelemetry.getTracer().startSpan('main');
+for (let i = 0; i < 10; i++) {
+  doWork(span);
+}
+// Be sure to end the span.
+span.end();
+
+// flush and close the connection.
+zipkinExporter.shutdown();
+jaegerExporter.shutdown();
+
+function doWork(parent) {
+  // Start another span. In this example, the main method already started a
+  // span, so that'll be the parent span, and this will be a child span.
+  const span = opentelemetry.getTracer().startSpan('doWork', {
+    parent: parent
+  });
+
+  // simulate some random work.
+  for (let i = 0; i <= Math.floor(Math.random() * 40000000); i++) { }
+
+  // Set attributes to the span.
+  span.setAttribute('key', 'value');
+
+  // Annotate our span to capture metadata about our operation
+  span.addEvent('invoking doWork').end();
+}

examples/basic-tracer-node/package.json

@@ -6,7 +6,8 @@
   "main": "index.js",
   "scripts": {
     "zipkin:basic": "cross-env EXPORTER=zipkin node ./index.js",
-    "jaeger:basic": "cross-env EXPORTER=jaeger node ./index.js"
+    "jaeger:basic": "cross-env EXPORTER=jaeger node ./index.js",
+    "multi_exporter": "node ./multi_exporter.js"
   },
   "repository": {
     "type": "git",