java/src/main/com/google/apphosting/utils/config/BackendsXmlReader.java

   1 // Copyright 2011 Google Inc. All Rights Reserved.
   2 package com.google.apphosting.utils.config;
   3
   4 import org.mortbay.xml.XmlParser;
   5
   6 import java.io.InputStream;
   7 import java.util.EnumSet;
   8 import java.util.Iterator;
   9
  10 /**
  11  * Creates a {@link BackendsXml} instance from
  12  * <appdir>WEB-INF/backends.xml.  If you want to read the
  13  * configuration from a different file, subclass and override
  14  * {@link #getFilename()}.  If you want to read the configuration from
  15  * something that isn't a file, subclass and override
  16  * {@link #getInputStream()}.
  17  *
  18  */
  19 public class BackendsXmlReader extends AbstractConfigXmlReader<BackendsXml> {
  20
  21   private static final String FILENAME = "WEB-INF/backends.xml";
  22
  23   /**
  24    * Constructs the reader for {@code backends.xml} in a given application directory.
  25    * @param appDir the application directory
  26    */
  27   public BackendsXmlReader(String appDir) {
  28     super(appDir, false);
  29   }
  30
  31   /**
  32    * Parses the config file.
  33    * @return A {@link BackendsXml} object representing the parsed configuration.
  34    */
  35   public BackendsXml readBackendsXml() {
  36     return readConfigXml();
  37   }
  38
  39   @Override
  40   protected BackendsXml processXml(InputStream is) {
  41     BackendsXml backendsXml = new BackendsXml();
  42
  43     XmlParser.Node rootNode = getTopLevelNode(is);
  44     Iterator<?> backends = rootNode.iterator("backend");
  45     while (backends.hasNext()) {
  46       XmlParser.Node node = (XmlParser.Node) backends.next();
  47       backendsXml.addBackend(convertBackendNode(node));
  48     }
  49
  50     return backendsXml;
  51   }
  52
  53   @Override
  54   protected String getRelativeFilename() {
  55     return FILENAME;
  56   }
  57
  58   private BackendsXml.Entry convertBackendNode(XmlParser.Node node) {
  59     String name = trim(node.getAttribute("name"));
  60     Integer instances = null;
  61     String instanceClass = node.getString("class", false, true);
  62     Integer maxConcurrentRequests = null;
  63     EnumSet<BackendsXml.Option> options = EnumSet.noneOf(BackendsXml.Option.class);
  64     {
  65       XmlParser.Node subNode = node.get("instances");
  66       if (subNode != null) {
  67         instances = Integer.valueOf(getTextNode(subNode));
  68       }
  69     }
  70     {
  71       XmlParser.Node subNode = node.get("max-concurrent-requests");
  72       if (subNode != null) {
  73         maxConcurrentRequests = Integer.valueOf(getTextNode(subNode));
  74       }
  75     }
  76     {
  77       XmlParser.Node subNode = node.get("options");
  78       if (subNode != null) {
  79         XmlParser.Node failFastNode = subNode.get("fail-fast");
  80         if (failFastNode != null) {
  81           if (getBooleanValue(failFastNode)) {
  82             options.add(BackendsXml.Option.FAIL_FAST);
  83           }
  84         }
  85         XmlParser.Node dynamicNode = subNode.get("dynamic");
  86         if (dynamicNode != null) {
  87           if (getBooleanValue(dynamicNode)) {
  88             options.add(BackendsXml.Option.DYNAMIC);
  89           }
  90         }
  91         XmlParser.Node publicNode = subNode.get("public");
  92         if (publicNode != null) {
  93           if (getBooleanValue(publicNode)) {
  94             options.add(BackendsXml.Option.PUBLIC);
  95           }
  96         }
  97       }
  98     }
  99     return new BackendsXml.Entry(name, instances, instanceClass,
 100                                  maxConcurrentRequests, options, null);
 101   }
 102
 103   private boolean getBooleanValue(XmlParser.Node node) {
 104     String value = getTextNode(node);
 105     value = value.trim();
 106     return (value.equalsIgnoreCase("true") || value.equals("1"));
 107   }
 108
 109   private String getTextNode(XmlParser.Node node) {
 110     String value = (String) node.get(0);
 111     if (value == null) {
 112       value = "";
 113     }
 114     return value;
 115   }
 116
 117   private String trim(String attribute) {
 118     return attribute == null ? null : attribute.trim();
 119   }
 120 }