4 files changed, 119 insertions, 55 deletions
diff --git a/src/uk/org/ury/server/protocol/DecodeFailureException.java b/src/uk/org/ury/server/protocol/DecodeFailureException.java
new file mode 100644
index 0000000..faa2b1f
--- /dev/null
+++ b/src/uk/org/ury/server/protocol/DecodeFailureException.java
@@ -0,0 +1,31 @@
+/**
+ * 
+ */
+package uk.org.ury.server.protocol;
+
+/**
+ * Exception thrown when the protocol decoder fails.
+ * 
+ * @author  Matt Windsor
+ */
+
+public class DecodeFailureException extends Exception
+{
+  /**
+   * 
+   */
+  private static final long serialVersionUID = -3972492943653273528L;
+
+  
+  /**
+   * Construct a new DecodeFailureException with a reason.
+   * 
+   * @param reason  The reason for throwing the exception.
+   */
+  
+  public
+  DecodeFailureException (String reason)
+  {
+    super (reason);
+  }
+}
diff --git a/src/uk/org/ury/server/protocol/Directive.java b/src/uk/org/ury/server/protocol/Directive.java
index 0d7a162..ce1b8b9 100644
--- a/src/uk/org/ury/server/protocol/Directive.java
+++ b/src/uk/org/ury/server/protocol/Directive.java
@@ -11,59 +11,8 @@ package uk.org.ury.server.protocol;
 
 public enum Directive
   {
-    // ID           String representation  Singleton?
-    
-    /** Directive marking the start of an item block. */ 
-    ITEM_START      ("ITEM-START"        , false),
-    
-    /** Directive marking a property inside an item block. */  
-    ITEM_PROPERTY   ("PROP"              , false),
-    
-    /** Directive marking the end of an item block. */
-    ITEM_END        ("ITEM-END"          , false);
-    
-    
-    
-    private String strRep;        // String representation
-    private boolean isSingleton;  // Is a singleton?
-
-    
-    /**
-     * Construct a new Directive.
-     * 
-     * @param strRep  The string representation of the Directive.
-     * 
-     * @param isSingleton  If true, then the Directive accepts no 
-     *                     properties.  If false, then the Directive 
-     *                     must be provided with at least one.
-     */
-    
-    private
-    Directive (String strRep, boolean isSingleton)
-    {
-      this.strRep = strRep;
-      this.isSingleton = isSingleton;
-    }
-    
-    
-    /**
-     * @return  the string representation.
-     */
-    
-    public String
-    toString ()
-    {
-      return strRep;
-    }
-    
-    
-    /**
-     * @return  true if the directive has no properties.
-     */
-    
-    public Boolean
-    isSingleton ()
-    {
-      return isSingleton;
-    }
+    INFO,    // Information string (can usually be ignored)
+    ITEMS,   // Item 
+    STATUS,  // Status code (from the enum Status)
+    REASON;  // Error reason
   }
diff --git a/src/uk/org/ury/server/protocol/ProtocolUtils.java b/src/uk/org/ury/server/protocol/ProtocolUtils.java
new file mode 100644
index 0000000..e45bb22
--- /dev/null
+++ b/src/uk/org/ury/server/protocol/ProtocolUtils.java
@@ -0,0 +1,67 @@
+/**
+ * 
+ */
+package uk.org.ury.server.protocol;
+
+import java.util.Map;
+
+import org.json.simple.JSONObject;
+import org.json.simple.JSONValue;
+
+
+/**
+ * Utilities for converting between strings encoded in the response 
+ * protocol and collections of items.
+ * 
+ * @author  Matt Windsor
+ *
+ */
+
+public class ProtocolUtils
+{
+  /**
+   * Encode a key-value map into a protocol string.
+   * 
+   * The map can contain strings, lists and other maps.  Other 
+   * types may be accepted by the underlying encoding engine, 
+   * but the above types are the only ones explicitly accepted.
+   * 
+   * @param items  The key-value map of items, which should contain 
+   *               strings, lists and maps.  The keys of any map 
+   *               should be protocol directives.
+   *               
+   * @return       A string containing the encoded representation of 
+   *               the map.
+   */
+  
+  public static String
+  encode (Map<String, Object> items)
+  {
+    return JSONValue.toJSONString (items);
+  }
+  
+  
+  /**
+   * Decode a protocol string into a key-value map.
+   * 
+   * @param string  The string to decode.
+   * 
+   * @return        A key-value map mapping directives to strings,
+   *                lists and maps.
+   *                
+   * @throws        DecodeFailureException if the decoding engine 
+   *                returns something other than a map.
+   */
+  
+  public static Map<?, ?>
+  decode (String string) throws DecodeFailureException
+  {
+    Object result = JSONValue.parse (string);
+    
+    if (result instanceof JSONObject)
+      return (JSONObject) result;
+    else
+      throw new DecodeFailureException ("Result not a map.");
+  }
+  
+}
diff --git a/src/uk/org/ury/server/protocol/Status.java b/src/uk/org/ury/server/protocol/Status.java
new file mode 100644
index 0000000..c9d848d
--- /dev/null
+++ b/src/uk/org/ury/server/protocol/Status.java
@@ -0,0 +1,17 @@
+/**
+ * 
+ */
+package uk.org.ury.server.protocol;
+
+
+/**
+ * Statuses that can follow the STATUS directory.
+ * 
+ * @author  Matt Windsor
+ */
+
+public enum Status
+  {
+    OK,    // The request was processed OK; response should be valid
+    ERROR  // An error occurred; message provided as REASON directive
+  }