feat: add OpenTracing example

examples/opentracing-shim/README.md

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+# Overview
+
+OpenTelemetry Opentracing shim allows user to report to OpenTelemetry with existing OpenTracing instrumentation.
+
+This is a simple example that demonstrates how existing OpenTracing instrumentation can be integrated with OpenTelemetry.
+
+The example shows key aspects of tracing such as
+
+- Root Span (on client)
+- Child Span from a remote parent (on server)
+- Span Tag
+- Span Log
+
+## Installation
+```sh
+# from this directory
+$ npm install
+```
+
+## Run the Application
+
+### Zipkin
+- Setup [Zipkin Tracing UI](https://zipkin.io/pages/quickstart.html)
+
+- Run the server
+```sh
+# from this directory
+$ npm run zipkin:server
+```
+
+- Run the client
+```sh
+# from this directory
+$ npm run zipkin:client
+```
+
+- Check trace
+
+  `zipkin:client` should output the `traceId` in the terminal.
+
+  Go to Zipkin with your browser [http://localhost:9411/zipkin/traces/(your-trace-id)]() (e.g http://localhost:9411/zipkin/traces/4815c3d576d930189725f1f1d1bdfcc6)
+
+
+<p align="center"><img src="./images/zipkin-ui.png?raw=true"/></p>
+
+### Jaeger
+- Setup [Jaeger Tracing UI](https://www.jaegertracing.io/docs/latest/getting-started/#all-in-one)
+
+- Run the server
+```sh
+# from this directory
+$ npm run jaeger:server
+```
+
+- Run the client
+```sh
+# from this directory
+$ npm run jaeger:client
+```
+
+- Check trace
+
+  `jaeger:client` should output the `traceId` in the terminal.
+
+  Go to Jaeger with your browser [http://localhost:16686/trace/(your-trace-id)]() (e.g http://localhost:16686/trace/4815c3d576d930189725f1f1d1bdfcc6)
+
+<p align="center"><img src="images/jaeger-ui.png?raw=true"/></p>
+
+## Useful links
+- For more information on OpenTelemetry, visit: <https://opentelemetry.io/>
+- For more information on OpenTelemetry for Node.js, visit: <https://github.com/open-telemetry/opentelemetry-js/tree/master/packages/opentelemetry-node>
+- For more information on OpenTracing, visit: <https://opentracing.io/>
+
+## LICENSE
+
+Apache License 2.0

examples/opentracing-shim/client.js

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+"use strict";
+
+const http = require("http");
+const opentracing = require("opentracing");
+require("./tracer").init("http_client_service");
+
+const tracer = opentracing.globalTracer();
+
+makeRequest();
+
+async function makeRequest() {
+  const span = tracer.startSpan("make_request");
+
+  const headers = {};
+  tracer.inject(span, opentracing.FORMAT_HTTP_HEADERS, headers);
+
+  http
+    .get(
+      {
+        host: "localhost",
+        port: 3000,
+        path: "/",
+        headers
+      },
+      resp => {
+        let data = "";
+
+        resp.on("data", chunk => {
+          data += chunk;
+        });
+
+        resp.on("end", async () => {
+          console.log(JSON.parse(data));
+          span.finish();
+
+          console.log("Sleeping 5 seconds before shutdown to ensure all records are flushed.");
+          setTimeout(() => { console.log('Completed.'); }, 5000);
+          process.exit(0);
+        });
+      }
+    )
+    .on("error", err => {
+      console.log("Error: " + err.message);
+    });
+}

examples/opentracing-shim/package.json

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+{
+  "name": "opentracing-shim",
+  "private": true,
+  "version": "0.2.0",
+  "description": "Example of using @opentelemetry/shim-opentracing in Node.js",
+  "main": "index.js",
+  "scripts": {
+    "zipkin:client": "cross-env EXPORTER=zipkin node ./client.js",
+    "zipkin:server": "cross-env EXPORTER=zipkin node ./server.js",
+    "jaeger:client": "cross-env EXPORTER=jaeger node ./client.js",
+    "jaeger:server": "cross-env EXPORTER=jaeger node ./server.js"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+ssh://git@github.com/open-telemetry/opentelemetry-js.git"
+  },
+  "keywords": [
+    "opentelemetry",
+    "http",
+    "tracing",
+    "opentracing"
+  ],
+  "engines": {
+    "node": ">=8"
+  },
+  "author": "OpenTelemetry Authors",
+  "license": "Apache-2.0",
+  "bugs": {
+    "url": "https://github.com/open-telemetry/opentelemetry-js/issues"
+  },
+  "dependencies": {
+    "@opentelemetry/exporter-jaeger": "^0.2.0",
+    "@opentelemetry/exporter-zipkin": "^0.2.0",
+    "@opentelemetry/node": "^0.2.0",
+    "@opentelemetry/shim-opentracing": "^0.2.0",
+    "opentracing": "^0.14.4"
+  },
+  "homepage": "https://github.com/open-telemetry/opentelemetry-js#readme",
+  "devDependencies": {
+    "cross-env": "^6.0.0"
+  }
+}

examples/opentracing-shim/server.js

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+"use strict";
+
+const http = require("http");
+const opentracing = require("opentracing");
+const utils = require("./utils");
+require("./tracer").init("http_server_service");
+
+const tracer = opentracing.globalTracer();
+
+startServer(3000);
+
+function startServer(port) {
+  const server = http.createServer(handleRequest);
+
+  server.listen(port, err => {
+    if (err) throw err;
+
+    console.log(`Server is listening on ${port}`);
+  });
+}
+
+async function handleRequest(req, res) {
+  const parentSpan = tracer.extract(
+    opentracing.FORMAT_HTTP_HEADERS,
+    req.headers
+  );
+
+  const span = tracer.startSpan("handle_request", {
+    childOf: parentSpan
+  });
+
+  span.setTag("custom", "tag value");
+  span.setTag("alpha", "1000");
+
+  await doSomething(span);
+
+  res.writeHead(200, { "Content-Type": "application/json" });
+  res.write(JSON.stringify({ status: "OK", traceId: span.context().toTraceId() }));
+
+  res.end();
+  span.finish();
+}
+
+async function doSomething(parentSpan) {
+  const span = tracer.startSpan("do_something", { childOf: parentSpan });
+
+  span.setTag("alpha", "200");
+  span.setTag("beta", "50");
+  span.log({ state: "waiting" });
+
+  // deliberately sleeping to mock some action.
+  await utils.sleep(1000);
+
+  span.finish();
+}

examples/opentracing-shim/tracer.js

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+"use strict";
+
+const { NodeTracer } = require("@opentelemetry/node");
+const { SimpleSpanProcessor } = require("@opentelemetry/tracing");
+const { JaegerExporter } = require("@opentelemetry/exporter-jaeger");
+const { ZipkinExporter } = require("@opentelemetry/exporter-zipkin");
+const { TracerShim } = require("@opentelemetry/shim-opentracing");
+
+const opentracing = require("opentracing");
+
+function init(serviceName) {
+  let exporter;
+  if (process.env.EXPORTER.toLowerCase().startsWith("z")) {
+    exporter = new ZipkinExporter({ serviceName });
+  } else {
+    exporter = new JaegerExporter({ serviceName, flushInterval: 100 });
+  }
+
+  const tracer = new NodeTracer();
+
+  tracer.addSpanProcessor(new SimpleSpanProcessor(exporter));
+
+  opentracing.initGlobalTracer(new TracerShim(tracer));
+}
+
+exports.init = init;

examples/opentracing-shim/utils.js

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+"use strict";
+
+async function sleep(ms) {
+  return new Promise(resolve => setTimeout(resolve, ms));
+}
+
+exports.sleep = sleep;