Restructured the project creating a router directory for the router bundle implementa...

[xmlrouter] / router / impl / src / main / java / org / wamblee / xmlrouter / impl / RobustDestination.java

diff --git a/router/impl/src/main/java/org/wamblee/xmlrouter/impl/RobustDestination.java b/router/impl/src/main/java/org/wamblee/xmlrouter/impl/RobustDestination.java
new file mode 100644 (file)
index 0000000..3fc48d7
--- /dev/null
+++ b/router/impl/src/main/java/org/wamblee/xmlrouter/impl/RobustDestination.java
@@ -0,0 +1,145 @@
+/*
+ * Copyright 2005-2011 the original author or authors.
+ * 
+ * Licensed 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.wamblee.xmlrouter.impl;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import javax.xml.transform.dom.DOMSource;
+
+import org.wamblee.xml.XMLDocument;
+import org.wamblee.xmlrouter.common.Id;
+import org.wamblee.xmlrouter.subscribe.Destination;
+
+/**
+ * Provides robustness for the use of externally provided destinations by
+ * catching null return values and exceptions and providing usable default
+ * return values.
+ * 
+ * @author Erik Brakkee
+ * 
+ */
+public class RobustDestination implements Destination {
+
+    private static final Logger LOGGER = Logger
+        .getLogger(RobustDestination.class.getName());
+
+    private Id<Destination> id;
+    private Destination destination;
+
+    public RobustDestination(Id<Destination> aId, Destination aDestination) {
+        id = aId;
+        destination = aDestination;
+    }
+
+    @Override
+    public String getName() {
+        try {
+            String res = destination.getName();
+            if (res == null) {
+                logNameReturnedNull();
+                return Constants.UNKNOWN_DESTINATION_NAME.toString();
+            }
+            return res;
+        } catch (Exception e) {
+            logNameThrewException(e);
+            return Constants.UNKNOWN_DESTINATION_NAME.toString();
+        }
+    }
+
+    @Override
+    public Collection<String> chooseFromTargetTypes(
+        Collection<String> aPossibleTargetTypes) {
+        try {
+            Collection<String> res = destination
+                .chooseFromTargetTypes(aPossibleTargetTypes);
+            if (res == null) {
+                logChooseFromTargetTypesReturnedNull(aPossibleTargetTypes);
+                return Collections.EMPTY_LIST;
+            }
+            Collection<String> finalRes = new ArrayList<String>();
+            for (String type : res) {
+                if (!aPossibleTargetTypes.contains(type)) {
+                    logChooseFromTargetTypesReturnedInvalidType(
+                        aPossibleTargetTypes, type);
+                } else {
+                    finalRes.add(type);
+                }
+            }
+            return finalRes;
+        } catch (Exception e) {
+            logChooseFromTargetTypesThrewException(aPossibleTargetTypes, e);
+            return Collections.EMPTY_LIST;
+        }
+    }
+
+    @Override
+    public boolean receive(DOMSource aEvent) {
+        try {
+            return destination.receive(aEvent);
+        } catch (Exception e) {
+            logReceiveThrewException(aEvent, e);
+            return false;
+        }
+    }
+
+    private void logNameThrewException(Exception aE) {
+        LOGGER.log(Level.WARNING,
+            "getName() threw exception for destination id " + id +
+                " returning name " + Constants.UNKNOWN_DESTINATION_NAME +
+                " instead", aE);
+    }
+
+    private void logNameReturnedNull() {
+        LOGGER.log(Level.WARNING,
+            "getName() returned null for destination id " + id +
+                " returning name " + Constants.UNKNOWN_DESTINATION_NAME +
+                " instead");
+    }
+
+    private void logChooseFromTargetTypesReturnedInvalidType(
+        Collection<String> aPossibleTargetTypes, String aType) {
+        LOGGER
+            .log(
+                Level.WARNING,
+                "chooseFromTargetTypes() for destination {0} returned invalid type ''{1}'' which is not in the offered set of types {2}",
+                new Object[] { id, aType, aPossibleTargetTypes.toString() });
+    }
+
+    private void logChooseFromTargetTypesReturnedNull(
+        Collection<String> aPossibleTargetTypes) {
+        LOGGER.log(Level.WARNING,
+            "chooseFromTargetTypes() returned null for destination " + id);
+    }
+
+    private void logChooseFromTargetTypesThrewException(
+        Collection<String> aPossibleTargetTypes, Exception aE) {
+        LOGGER
+            .log(
+                Level.WARNING,
+                "chooseFromTargetTypes() threw exception for destination " + id,
+                aE);
+    }
+
+    private void logReceiveThrewException(DOMSource aEvent, Exception aE) {
+        LOGGER.log(Level.WARNING, "Receive threw exception for destination " +
+            id + " for event " + new XMLDocument(aEvent).print(true), aE);
+    }
+
+}