Index: src/java/org/apache/commons/chain/CatalogFactory.java
===================================================================
RCS file: /home/cvs/jakarta-commons/chain/src/java/org/apache/commons/chain/CatalogFactory.java,v
retrieving revision 1.5
diff -u -d -b -w -u -r1.5 CatalogFactory.java
--- src/java/org/apache/commons/chain/CatalogFactory.java	30 Nov 2004 05:52:22 -0000	1.5
+++ src/java/org/apache/commons/chain/CatalogFactory.java	30 Dec 2004 19:48:33 -0000
@@ -20,18 +20,37 @@
 import java.util.Map;
 import org.apache.commons.chain.impl.CatalogFactoryBase;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 /**
  * <p>A {@link CatalogFactory} is a class used to store and retrieve
  * {@link Catalog}s.  The factory allows for a default {@link Catalog}
  * as well as {@link Catalog}s stored with a name key.  Follows the
  * Factory pattern (see GoF).</p>
  *
+ * <p>The base <code>CatalogFactory</code> implementation also implements 
+ * a resolution mechanism which allows lookup of a command based on a single string
+ * which encodes both the catalog and command names.</p>
+ *
  * @author Sean Schofield
  * @version $Revision: 1.5 $ $Date: 2004/11/30 05:52:22 $
  */
 
 public abstract class CatalogFactory {
 
+    /**
+     * <p>The <code>Log</code> instance for this class.</p>
+     */
+    private static final Log log = LogFactory.getLog(CatalogFactory.class);
+
+    /**
+     * <p>Values passed to the <code>getCommand(String)</code> method should 
+     * use ":" as the delimiter between the "catalog" name and the "command" name.
+     * </p>
+     */
+    public static final String DELIMITER = ":";
+
 
     // --------------------------------------------------------- Public Methods
 
@@ -80,7 +99,64 @@
      */
     public abstract Iterator getNames();
 
+    /**
+     * <p>Return a <code>Command</code> based on the given ID.</p>
+     * <p>At this time, the structure of the ID is relatively simple:  If the
+     * ID contains a colon (:) character, treat the segment of the ID
+     * up to (but not including) the colon as the name of a catalog, and the 
+     * segment following the colon as a command name within that catalog.  If the 
+     * given ID contains no colon, treat the ID as the name of a command in 
+     * the default catalog.</p>
+     * <p>To preserve the possibility of future extensions to this lookup mechanism,
+     * the colon character should be considered reserved, and should not be used in 
+     * command names.  <code>commandID</code> values which contain more than one delimiter
+     * will cause an <code>IllegalArgumentException</code> to be thrown. </p>
+     * 
+     * @param commandID the identifier of the command to return.
+     * @return the command located with commandID, or null if either the command name
+     * or the catalog name cannot be resolved.
+     * @throws IllegalArgumentException if the commandID contains more than one delimiter.
+     */
+    public Command getCommand(String commandID) throws IllegalArgumentException {
+
+        String commandName = commandID;
+        String catalogName = null;
+        Catalog catalog = null;
+
+        if (commandID != null) {
+            int splitPos = commandID.indexOf(DELIMITER);
+            if (splitPos != -1) {
+                catalogName = commandID.substring(0, splitPos);
+                commandName = commandID.substring(splitPos + 1);
+                if (commandName.indexOf(DELIMITER) != -1) {
+                    throw new IllegalArgumentException("ID [" + 
+                            commandID + 
+                            "] has too many delimiters (reserved for future use)");
+                }
+
+            }
+        }
+
+        if (catalogName != null) {
+            catalog = this.getCatalog(catalogName);
+
+            if (catalog == null) { 
+                log.warn("No catalog found for name: " + catalogName + ".");
+                return null;
+            }
+
+        } else {
+            catalog = this.getCatalog();
 
+            if (catalog == null) { 
+                log.warn("No default catalog found.");
+                return null;
+            }
+
+        }
+
+        return catalog.getCommand(commandName);
+    }
     // ------------------------------------------------------- Static Variables
 
 
Index: src/test/org/apache/commons/chain/impl/CatalogFactoryBaseTestCase.java
===================================================================
RCS file: /home/cvs/jakarta-commons/chain/src/test/org/apache/commons/chain/impl/CatalogFactoryBaseTestCase.java,v
retrieving revision 1.3
diff -u -d -b -w -u -r1.3 CatalogFactoryBaseTestCase.java
--- src/test/org/apache/commons/chain/impl/CatalogFactoryBaseTestCase.java	9 Dec 2004 05:23:14 -0000	1.3
+++ src/test/org/apache/commons/chain/impl/CatalogFactoryBaseTestCase.java	30 Dec 2004 19:48:33 -0000
@@ -131,6 +131,48 @@
 
     }
 
+    public void testCatalogIdentifier() {
+
+        Catalog defaultCatalog = new CatalogBase();
+        Command defaultFoo = new NonDelegatingCommand();
+        defaultCatalog.addCommand("foo", defaultFoo);
+        Command fallback = new NonDelegatingCommand();
+        defaultCatalog.addCommand("noSuchCatalog:fallback", fallback);
+
+        factory.setCatalog(defaultCatalog);
+
+        Catalog specificCatalog = new CatalogBase();
+        Command specificFoo = new NonDelegatingCommand();
+        specificCatalog.addCommand("foo", specificFoo);
+        factory.addCatalog("specific", specificCatalog);
+
+        Command command = factory.getCommand("foo");
+        assertSame(defaultFoo, command);
+        
+        command = factory.getCommand("specific:foo");
+        assertSame(specificFoo, command);
+
+        command = factory.getCommand("void");
+        assertNull(command);
+
+        command = factory.getCommand("foo:void");
+        assertNull(command);
+
+        command = factory.getCommand("specific:void");
+        assertNull(command);
+
+        command = factory.getCommand("noSuchCatalog:fallback");
+        assertNull(command);
+
+        try {
+            command = factory.getCommand("multiple:delimiters:reserved");
+            fail("A command ID with more than one delimiter should throw an IllegalArgumentException");
+        }
+        catch (IllegalArgumentException ex) {
+            // expected behavior
+        }
+        
+    }
 
     // ------------------------------------------------------- Support Methods