code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC licenses this file
  // to you 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 org.openqa.selenium.grid.router;
  
  import static org.openqa.selenium.remote.http.Route.combine;
  import static org.openqa.selenium.remote.http.Route.get;
  import static org.openqa.selenium.remote.http.Route.matching;
  
  import com.google.common.collect.ImmutableSet;
  import org.openqa.selenium.grid.distributor.Distributor;
  import org.openqa.selenium.grid.sessionmap.SessionMap;
  import org.openqa.selenium.grid.sessionqueue.NewSessionQueue;
  import org.openqa.selenium.internal.Require;
  import org.openqa.selenium.remote.http.HttpClient;
  import org.openqa.selenium.remote.http.HttpRequest;
  import org.openqa.selenium.remote.http.HttpResponse;
  import org.openqa.selenium.remote.http.Routable;
  import org.openqa.selenium.remote.tracing.SpanDecorator;
  import org.openqa.selenium.remote.tracing.Tracer;
  import org.openqa.selenium.status.HasReadyState;
  
  /** A simple router that is aware of the selenium-protocol. */
  public class Router implements HasReadyState, Routable {
  
    private final Routable routes;
    private final SessionMap sessions;
    private final Distributor distributor;
    private final NewSessionQueue queue;
  
    public Router(
        Tracer tracer,
        HttpClient.Factory clientFactory,
        SessionMap sessions,
        NewSessionQueue queue,
        Distributor distributor) {
      Require.nonNull("Tracer to use", tracer);
      Require.nonNull("HTTP client factory", clientFactory);
  
      this.sessions = Require.nonNull("Session map", sessions);
      this.queue = Require.nonNull("New Session Request Queue", queue);
      this.distributor = Require.nonNull("Distributor", distributor);
  
      HandleSession sessionHandler = new HandleSession(tracer, clientFactory, sessions);
  
      routes =
          combine(
              get("/status").to(() -> new GridStatusHandler(tracer, distributor)),
              sessions.with(new SpanDecorator(tracer, req -> "session_map")),
              queue.with(new SpanDecorator(tracer, req -> "session_queue")),
              distributor.with(new SpanDecorator(tracer, req -> "distributor")),
              matching(req -> req.getUri().startsWith("/session/")).to(() -> sessionHandler));
    }
  
    @Override
    public boolean isReady() {
      try {
        return ImmutableSet.of(distributor, sessions, queue).parallelStream()
            .map(HasReadyState::isReady)
            .reduce(true, Boolean::logicalAnd);
      } catch (RuntimeException e) {
        return false;
      }
    }
  
    @Override
    public boolean matches(HttpRequest req) {
      return routes.matches(req);
    }
  
    @Override
    public HttpResponse execute(HttpRequest req) {
      return routes.execute(req);
    }
  }
  