java/src/main/com/google/appengine/tools/development/LocalApiProxyServletFilter.java

   1 // Copyright 2008 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.tools.development;
   4
   5 import com.google.apphosting.api.ApiProxy;
   6 import com.google.apphosting.utils.config.AppEngineWebXml;
   7 import com.google.apphosting.utils.config.AppEngineWebXmlReader;
   8 import com.google.apphosting.utils.config.WebModule;
   9
  10 import java.io.File;
  11 import java.io.IOException;
  12 import java.io.InputStream;
  13 import java.util.logging.Logger;
  14
  15 import javax.servlet.Filter;
  16 import javax.servlet.FilterChain;
  17 import javax.servlet.FilterConfig;
  18 import javax.servlet.ServletContext;
  19 import javax.servlet.ServletException;
  20 import javax.servlet.ServletRequest;
  21 import javax.servlet.ServletResponse;
  22 import javax.servlet.http.HttpServletRequest;
  23
  24 /**
  25  * This filter is not currently used.  It was originally written for
  26  * IBM so they could see how to use our API's from their own webserver.
  27  * We kept it around because we'd ultimately like to use this ourselves but
  28  * we don't currently have a way to ensure that this filter runs before any
  29  * other filters get initialized.
  30  *
  31  * {@code LocalApiProxyServletFilter} is a servlet {@link Filter} that
  32  * sets up {@link ApiProxy} for use with the stub API implementations.
  33  *
  34  * <p>There are two parts to this:<ul>
  35
  36  * <li>At initialization, this filter installs a {@link
  37  * ApiProxy.Delegate} instance that locates any API stub
  38  * implementations on the classpath and registers them for use by
  39  * future requests.  It also looks for an App Engine-specific
  40  * deployment descriptor ({@code WEB-INF/appengine-web.xml}) and
  41  * parses it to obtain some metadata about the application
  42  * (e.g. application identifier).</li>
  43  *
  44  * <li>Around each request, a {@link ApiProxy.Environment} instance is
  45  * installed into a {@link ThreadLocal} managed by {@link ApiProxy}.
  46  * This environment instance contains the application metadata that
  47  * was extracted earlier, and also provides access to the
  48  * authentication data maintained by the stub implementation of the
  49  * Users API.</li> </ul>
  50  *
  51  * N.B. Does not support Modules.
  52  *
  53  */
  54 @Deprecated
  55 public class LocalApiProxyServletFilter implements Filter {
  56   private static final Logger logger = Logger.getLogger(LocalApiProxyServletFilter.class.getName());
  57   private static final String AE_WEB_XML = "/WEB-INF/appengine-web.xml";
  58
  59   private AppEngineWebXml appEngineWebXml;
  60
  61   /**
  62    * Register a custom {@link ApiProxy.Delegate instance}.
  63    */
  64   @Override
  65   public void init(FilterConfig config) {
  66     logger.info("Filter initialization invoked -- registering ApiProxy delegate.");
  67     ApiProxyLocalFactory factory = new ApiProxyLocalFactory();
  68     ApiProxy.setDelegate(factory.create(getLocalServerEnvironment(config)));
  69
  70     logger.info("Parsing custom deployment descriptor (" + AE_WEB_XML + ").");
  71     ServletAppEngineWebXmlReader reader =
  72         new ServletAppEngineWebXmlReader(config.getServletContext());
  73     appEngineWebXml = reader.readAppEngineWebXml();
  74     logger.info("Application identifier is: " + appEngineWebXml.getAppId());
  75   }
  76
  77   private LocalServerEnvironment getLocalServerEnvironment(final FilterConfig config) {
  78     return new LocalServerEnvironment() {
  79
  80       @Override
  81       public File getAppDir() {
  82         return new File(".");
  83       }
  84
  85       @Override
  86       public String getAddress() {
  87         throw new UnsupportedOperationException();
  88       }
  89
  90       @Override
  91       public int getPort() {
  92         throw new UnsupportedOperationException();
  93       }
  94
  95       @Override
  96       public String getHostName() {
  97         throw new UnsupportedOperationException();
  98       }
  99
 100       @Override
 101       public void waitForServerToStart() { }
 102
 103       @Override
 104       public boolean simulateProductionLatencies() {
 105         return true;
 106       }
 107
 108       @Override
 109       public boolean enforceApiDeadlines() {
 110         return false;
 111       }
 112     };
 113   }
 114
 115   /**
 116    * Remove the custom {@link ApiProxy.Delegate} instance.
 117    */
 118   @Override
 119   public void destroy() {
 120     logger.info("Filter destruction invoked -- removing delegate.");
 121     ApiProxy.setDelegate(null);
 122   }
 123
 124   /**
 125    * Wrap the request with calls to the environment-management method
 126    * on {@link ApiProxy}.
 127    */
 128   @Override
 129   public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
 130       throws IOException, ServletException {
 131     HttpServletRequest httpRequest = (HttpServletRequest) request;
 132
 133     logger.fine("Filter received a request, setting environment ThreadLocal.");
 134     ApiProxy.setEnvironmentForCurrentThread(new LocalHttpRequestEnvironment(
 135         appEngineWebXml.getAppId(), WebModule.getModuleName(appEngineWebXml),
 136         appEngineWebXml.getMajorVersionId(), LocalEnvironment.MAIN_INSTANCE,
 137         request.getLocalPort(), httpRequest, null, null));
 138     try {
 139       chain.doFilter(request, response);
 140     } finally {
 141       logger.fine("Request has completed.  Removing environment ThreadLocal.");
 142       ApiProxy.clearEnvironmentForCurrentThread();
 143     }
 144   }
 145
 146   /**
 147    * {@code ServletAppEngineWebXmlReader} is a specialization of
 148    * {@link AppEngineWebXmlReader} that reads the custom deployment
 149    * descriptor ({@code WEB-INF/appengine-web.xml}) from a {@link
 150    * ServletContext} rather than looking for an actual file on the
 151    * filesystem.
 152    */
 153   private static class ServletAppEngineWebXmlReader extends AppEngineWebXmlReader {
 154     private final ServletContext context;
 155
 156     public ServletAppEngineWebXmlReader(ServletContext context) {
 157       super("");
 158       this.context = context;
 159     }
 160
 161     @Override
 162     protected InputStream getInputStream() {
 163       return context.getResourceAsStream(AE_WEB_XML);
 164     }
 165   }
 166 }