wamblee.org Git - xmlrouter/blob - impl/src/main/java/org/wamblee/xmlrouter/impl/RobustDestination.java

   1 package org.wamblee.xmlrouter.impl;
   2
   3 import java.util.ArrayList;
   4 import java.util.Collection;
   5 import java.util.Collections;
   6 import java.util.logging.Level;
   7 import java.util.logging.Logger;
   8
   9 import javax.xml.transform.dom.DOMSource;
  10
  11 import org.wamblee.xml.XMLDocument;
  12 import org.wamblee.xmlrouter.common.Id;
  13 import org.wamblee.xmlrouter.subscribe.Destination;
  14
  15 /**
  16  * Provides robustness for the use of externally provided destinations by
  17  * catching null return values and exceptions and providing usable default
  18  * return values.
  19  *
  20  * @author Erik Brakkee
  21  *
  22  */
  23 public class RobustDestination implements Destination {
  24
  25     private static final Logger LOGGER = Logger
  26         .getLogger(RobustDestination.class.getName());
  27
  28     private Id<Destination> id;
  29     private Destination destination;
  30
  31     public RobustDestination(Id<Destination> aId, Destination aDestination) {
  32         id = aId;
  33         destination = aDestination;
  34     }
  35
  36     @Override
  37     public String getName() {
  38         try {
  39             String res = destination.getName();
  40             if (res == null) {
  41                 logNameReturnedNull();
  42                 return Constants.UNKNOWN_DESTINATION_NAME.toString();
  43             }
  44             return res;
  45         } catch (Exception e) {
  46             logNameThrewException(e);
  47             return Constants.UNKNOWN_DESTINATION_NAME.toString();
  48         }
  49     }
  50
  51     @Override
  52     public Collection<String> chooseFromTargetTypes(
  53         Collection<String> aPossibleTargetTypes) {
  54         try {
  55             Collection<String> res = destination
  56                 .chooseFromTargetTypes(aPossibleTargetTypes);
  57             if (res == null) {
  58                 logChooseFromTargetTypesReturnedNull(aPossibleTargetTypes);
  59                 return Collections.EMPTY_LIST;
  60             }
  61             Collection<String> finalRes = new ArrayList<String>();
  62             for (String type : res) {
  63                 if (!aPossibleTargetTypes.contains(type)) {
  64                     logChooseFromTargetTypesReturnedInvalidType(
  65                         aPossibleTargetTypes, type);
  66                 } else {
  67                     finalRes.add(type);
  68                 }
  69             }
  70             return finalRes;
  71         } catch (Exception e) {
  72             logChooseFromTargetTypesThrewException(aPossibleTargetTypes, e);
  73             return Collections.EMPTY_LIST;
  74         }
  75     }
  76
  77     @Override
  78     public boolean receive(DOMSource aEvent) {
  79         try {
  80             return destination.receive(aEvent);
  81         } catch (Exception e) {
  82             logReceiveThrewException(aEvent, e);
  83             return false;
  84         }
  85     }
  86
  87     private void logNameThrewException(Exception aE) {
  88         LOGGER.log(Level.WARNING,
  89             "getName() threw exception for destination id " + id +
  90                 " returning name " + Constants.UNKNOWN_DESTINATION_NAME +
  91                 " instead", aE);
  92     }
  93
  94     private void logNameReturnedNull() {
  95         LOGGER.log(Level.WARNING,
  96             "getName() returned null for destination id " + id +
  97                 " returning name " + Constants.UNKNOWN_DESTINATION_NAME +
  98                 " instead");
  99     }
 100
 101     private void logChooseFromTargetTypesReturnedInvalidType(
 102         Collection<String> aPossibleTargetTypes, String aType) {
 103         LOGGER
 104             .log(
 105                 Level.WARNING,
 106                 "chooseFromTargetTypes() for destination {0} returned invalid type ''{1}'' which is not in the offered set of types {2}",
 107                 new Object[] { id, aType, aPossibleTargetTypes.toString() });
 108     }
 109
 110     private void logChooseFromTargetTypesReturnedNull(
 111         Collection<String> aPossibleTargetTypes) {
 112         LOGGER.log(Level.WARNING,
 113             "chooseFromTargetTypes() returned null for destination " + id);
 114     }
 115
 116     private void logChooseFromTargetTypesThrewException(
 117         Collection<String> aPossibleTargetTypes, Exception aE) {
 118         LOGGER
 119             .log(
 120                 Level.WARNING,
 121                 "chooseFromTargetTypes() threw exception for destination " + id,
 122                 aE);
 123     }
 124
 125     private void logReceiveThrewException(DOMSource aEvent, Exception aE) {
 126         LOGGER.log(Level.WARNING, "Receive threw exception for destination " +
 127             id + " for event " + new XMLDocument(aEvent).print(true), aE);
 128     }
 129
 130 }