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HelloWorldServer.java
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HelloWorldServer.java
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/*
* Copyright 2019, OpenCensus Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.opencensus.examples.http.jetty.server;
import io.opencensus.contrib.http.servlet.OcHttpServletFilter;
import io.opencensus.contrib.http.util.HttpViews;
import io.opencensus.exporter.stats.prometheus.PrometheusStatsCollector;
import io.opencensus.exporter.trace.jaeger.JaegerTraceExporter;
import io.opencensus.exporter.trace.logging.LoggingTraceExporter;
import io.opencensus.trace.Tracing;
import io.opencensus.trace.config.TraceConfig;
import io.opencensus.trace.samplers.Samplers;
import io.prometheus.client.exporter.HTTPServer;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.util.EnumSet;
import javax.servlet.AsyncContext;
import javax.servlet.DispatcherType;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.WriteListener;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.handler.AbstractHandler;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;
/** Sample application that shows how to instrument jetty server. */
public class HelloWorldServer extends AbstractHandler {
private static final Logger logger = Logger.getLogger(HelloWorldServer.class.getName());
public static class HelloServlet extends HttpServlet {
private static String body = "<h1>Hello World Servlet Get</h1>";
private static final long serialVersionUID = 1L;
private void blockingGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String str = body.concat("<h3>blocking</h3>");
ByteBuffer content = ByteBuffer.wrap(str.getBytes(StandardCharsets.UTF_8));
PrintWriter pout = response.getWriter();
pout.print("<html><body>");
pout.print(str);
pout.print("</body></html>");
return;
}
private void asyncGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String str = body.concat("<h3>async</h3>");
ByteBuffer content = ByteBuffer.wrap(str.getBytes(StandardCharsets.UTF_8));
AsyncContext async = request.startAsync();
response.setContentType("text/html");
try {
Thread.sleep(100);
} catch (Exception e) {
logger.info("Error sleeping");
}
ServletOutputStream out = response.getOutputStream();
out.setWriteListener(
new WriteListener() {
@Override
public void onWritePossible() throws IOException {
while (out.isReady()) {
if (!content.hasRemaining()) {
response.setStatus(200);
async.complete();
return;
}
out.write(content.get());
}
}
@Override
public void onError(Throwable t) {
logger.info("Server onError callled");
getServletContext().log("Async Error", t);
async.complete();
}
});
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
if (request.getPathInfo().contains("async")) {
asyncGet(request, response);
} else {
blockingGet(request, response);
}
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// Read from request
StringBuilder buffer = new StringBuilder();
BufferedReader reader = request.getReader();
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
String data = buffer.toString();
PrintWriter pout = response.getWriter();
pout.print("<html><body>");
pout.print("<h3>Hello World Servlet Post</h3>");
pout.print("</body></html>");
return;
}
}
@Override
public void handle(
String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
response.setContentType("text/html;charset=utf-8");
response.setStatus(HttpServletResponse.SC_OK);
baseRequest.setHandled(true);
response.getWriter().println("<h1>Hello World. default handler.</h1>");
}
private static void initStatsExporter() throws IOException {
HttpViews.registerAllServerViews();
// Register Prometheus exporters and export metrics to a Prometheus HTTPServer.
// Refer to https://prometheus.io/ to run Prometheus Server.
PrometheusStatsCollector.createAndRegister();
HTTPServer prometheusServer = new HTTPServer(9090, true);
}
private static void initTracing() {
TraceConfig traceConfig = Tracing.getTraceConfig();
// default sampler is set to Samplers.alwaysSample() for demonstration. In production
// or in high QPS environment please use default sampler.
traceConfig.updateActiveTraceParams(
traceConfig.getActiveTraceParams().toBuilder().setSampler(Samplers.alwaysSample()).build());
// Register LoggingTraceExporter to see traces in logs.
LoggingTraceExporter.register();
// Register Jaeger Tracing. Refer to https://www.jaegertracing.io/docs/1.8/getting-started/ to
// run Jaeger
JaegerTraceExporter.createAndRegister("http://localhost:14268/api/traces", "helloworldserver");
}
/**
* HelloWorldServer starts a jetty server that responds to http request sent by {@link
* HelloWorldClient}. The server uses http servlet which is instrumented with opencensus to enable
* tracing and monitoring stats.
*/
public static void main(String[] args) throws Exception {
initTracing();
initStatsExporter();
Server server = new Server(8080);
ServletContextHandler contextHandler =
new ServletContextHandler(ServletContextHandler.SESSIONS);
contextHandler.setContextPath("/helloworld");
ServletHolder sh = new ServletHolder(new HelloServlet());
contextHandler.addServlet(sh, "/request/*");
// Enable tracing by adding OcHttpServleFilter for all path
contextHandler.addFilter(OcHttpServletFilter.class, "/*", EnumSet.of(DispatcherType.REQUEST));
// Uncomment following line to use B3Format for trace context propagation.
// contextHandler.setAttribute(
// OC_TRACE_PROPAGATOR, Tracing.getPropagationComponent().getB3Format());
// By default publicEndpoint parameter is set to false and incoming trace context is added as
// a parent.
// If the endpoint for http request is public then uncomment following line to set the
// publicEndpoint parameter to true. When set to true incoming trace context is added as a
// parent link instead of as a parent.
//
// contextHandler.setInitParameter(OC_PUBLIC_ENDPOINT, "true");
server.setHandler(contextHandler);
try {
server.start();
server.join();
} catch (Exception e) {
logger.error("Failed to start application", e);
}
}
}