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.environment.webserver;
  
  import org.openqa.selenium.WebDriverException;
  import org.openqa.selenium.net.NetworkUtils;
  
  public interface AppServer {
  
    String getHostName();
  
    String getAlternateHostName();
  
    String whereIs(String relativeUrl);
  
    String whereElseIs(String relativeUrl);
  
    String whereIsSecure(String relativeUrl);
  
    String whereIsWithCredentials(String relativeUrl, String user, String password);
  
    String create(Page page);
  
    void start();
  
    void stop();
  
    static String detectHostname() {
      String hostnameFromProperty = System.getenv("HOSTNAME");
      return hostnameFromProperty == null ? "localhost" : hostnameFromProperty;
    }
  
    static String detectAlternateHostname() {
      String alternativeHostnameFromProperty = System.getenv("ALTERNATIVE_HOSTNAME");
      if (alternativeHostnameFromProperty != null) {
        return alternativeHostnameFromProperty;
      }
  
      NetworkUtils networkUtils = new NetworkUtils();
      try {
        return networkUtils.getNonLoopbackAddressOfThisMachine();
      } catch (WebDriverException e) {
        return networkUtils.getPrivateLocalAddress();
      }
    }
  }
  