diff --git a/src/main/java/altk/comm/engine/Broadcast.java b/src/main/java/altk/comm/engine/Broadcast.java
index ed97912..85a614c 100644
--- a/src/main/java/altk/comm/engine/Broadcast.java
+++ b/src/main/java/altk/comm/engine/Broadcast.java
@@ -889,8 +889,8 @@ public abstract class Broadcast
 		statusBf.append("<job_summary completed='" + getCompletedJobCount() +
 		        "' ready='" + getPendingJobCount() + "'");
 		statusBf.append(" active='" + getActiveJobCount() + "'");
-		statusBf.append("></job_summary>");
-		statusBf.append("<daily_pause>" + daily_pause + "</daily_pause>\n");
+		statusBf.append("></job_summary>\n");
+		statusBf.append("<daily_pause>" + daily_pause + "</daily_pause>");
 		statusBf.append("<daily_resume>" + daily_resume + "</daily_resume>\n");
 		statusBf.append(additionalStatusXML());
 		statusBf.append("</" + topLevelTag + ">");
@@ -1440,11 +1440,12 @@ public abstract class Broadcast
 		}
 	}
 
+	@SuppressWarnings("unchecked")
 	public JSONObject getConfigJSON() {
-    	Map<Object, Object> dataMap = new HashMap<Object, Object>();
+    	JSONObject dataMap = new JSONObject();
     	dataMap.put(CommEngine.DAILY_PAUSE_KEY, daily_pause);
     	dataMap.put(CommEngine.DAILY_RESUME_KEY, daily_resume);
-		return new JSONObject(dataMap);
+		return dataMap;
 	}
 
 }
diff --git a/src/main/java/altk/comm/engine/CommEngine.java b/src/main/java/altk/comm/engine/CommEngine.java
index 43cc163..6cb061f 100644
--- a/src/main/java/altk/comm/engine/CommEngine.java
+++ b/src/main/java/altk/comm/engine/CommEngine.java
@@ -7,6 +7,7 @@ import java.io.IOException;
 import java.io.PrintWriter;
 import java.time.LocalTime;
 import java.time.format.DateTimeFormatter;
+import java.util.Date;
 import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -14,6 +15,8 @@ import java.util.Map;
 import java.util.Properties;
 import java.util.Vector;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
@@ -23,7 +26,6 @@ import javax.servlet.http.HttpServletResponse;
 
 import org.apache.log4j.Logger;
 import org.apache.log4j.PropertyConfigurator;
-import org.json.simple.JSONArray;
 import org.json.simple.JSONObject;
 import org.json.simple.parser.JSONParser;
 
@@ -102,8 +104,6 @@ public abstract class CommEngine extends HttpServlet
 		{
 			while (!threadShouldStop)
 			{
-		    	long startTime = System.currentTimeMillis();;
-
 		    	String timeOfDay = LocalTime.now().format(DateTimeFormatter.ofPattern("HH:mm"));
 		    	// Check for pause
 				for (Broadcast broadcast : broadcasts.values())
@@ -123,9 +123,8 @@ public abstract class CommEngine extends HttpServlet
 					else if (timeOfDay.equals(daily_resume)) broadcast.resume("clock", null);
 				}
 
-				// Wakes up every 1/2 minute to provide minute resolution
 				long currentTime = System.currentTimeMillis();
-				long sleepTime = startTime + 30*1000 - currentTime;
+				long sleepTime = 60000 + 30000 - currentTime % 60000;
 				if (sleepTime > 0)
 				{
 					try 
@@ -251,11 +250,7 @@ public abstract class CommEngine extends HttpServlet
             notInService = true;
             return;
         }
-        
-        // Set up periodic purge of stale broadcasts, based on deadBroadcastViewingMinutes
-        String periodStr = config.getProperty("dead_broadcast_viewing_period", Long.toString(DEAD_BROADCAST_VIEWING_PERIOD_DEFAULT));
-        deadBroadcastViewingMinutes = Long.parseLong(periodStr);
-        
+	        
         String timeOfDay, timeOfDayStr, key;
         key = DAILY_RESUME_KEY;
         timeOfDayStr = config.getProperty(key , "");
@@ -283,7 +278,18 @@ public abstract class CommEngine extends HttpServlet
         dailyClock = new DailyClock();
         dailyClock.start();
         
-        initChild();
+        try
+        {
+	        // Set up periodic purge of stale broadcasts, based on deadBroadcastViewingMinutes
+	        String periodStr = config.getProperty("dead_broadcast_viewing_period", Long.toString(DEAD_BROADCAST_VIEWING_PERIOD_DEFAULT));
+	        deadBroadcastViewingMinutes = Long.parseLong(periodStr);
+	
+	        initChild();
+        }
+        catch (Exception e)
+        {
+        	throw new ServletException(e.getMessage(), e);
+        }
     }
         
 	public int getPauseThreshold() 
@@ -463,29 +469,40 @@ public abstract class CommEngine extends HttpServlet
     	out.print(configuration);
     }
     
-    private JSONObject getConfigJSON()
+	@SuppressWarnings("unchecked")
+	private JSONObject getConfigJSON()
     {
-    	Map<Object, Object> dataMap = new HashMap<Object, Object>();
+    	JSONObject config = new JSONObject();
     	
     	// engine configuration
-    	Map<Object, Object> EngineMap = new HashMap<Object, Object>();
-    	dataMap.put("engine", EngineMap);
-    	EngineMap.put(DAILY_PAUSE_KEY, daily_pause);
-    	EngineMap.put(DAILY_RESUME_KEY, daily_resume);
+    	JSONObject EngineConfig = new JSONObject();
+    	config.put("engine", EngineConfig);
+    	EngineConfig.put(DAILY_PAUSE_KEY, daily_pause);
+    	EngineConfig.put(DAILY_RESUME_KEY, daily_resume);
     	
     	// broadcast configuration
-		Map<Object, Object> broadcastsMap = new HashMap<Object, Object>();
+    	JSONObject broadcastsConfig = new JSONObject();
     	synchronized (broadcasts) {
     		for (String broadcastId : broadcasts.keySet())
     		{
     			Broadcast broadcast = broadcasts.get(broadcastId);
     			if (broadcast.getState().isFinal) continue;
-				JSONObject configJSON = broadcast.getConfigJSON();
-    			broadcastsMap.put(broadcastId, configJSON);
+    			broadcastsConfig.put(broadcastId, broadcast.getConfigJSON());
     		}
     	}
-    	if (broadcastsMap.size() > 0) dataMap.put("broadcasts", broadcastsMap);
-    	return new JSONObject(dataMap);
+    	if (broadcastsConfig.size() > 0) config.put("broadcasts", broadcastsConfig);
+    	
+    	childAddConfig(config);
+    	
+    	return config;
+    }
+    
+    /**
+     * Derived class may add to configMap
+     * @param configMap
+     */
+    protected void childAddConfig(JSONObject config)
+    {
     }
 
 	private void cancelBroadcast(HttpServletRequest request, PrintWriter out)
@@ -538,7 +555,13 @@ public abstract class CommEngine extends HttpServlet
     protected static String checkTimeOfDay(String timeOfDay) {
     	timeOfDay = timeOfDay.trim();
     	if (timeOfDay.length() == 0) return timeOfDay;
-    	if (timeOfDay.length() != 5) return null;
+    	// pattern hh:mm
+    	Pattern pattern = Pattern.compile("^(\\d\\d):[0-5]\\d$");
+    	Matcher matcher = pattern.matcher(timeOfDay);
+    	if (!matcher.find()) return null;
+    	// Check hour in range
+    	String hh = matcher.group(1);
+    	if (Integer.parseInt(hh) > 23) return null;
     	return timeOfDay;
     }
     
@@ -548,7 +571,8 @@ public abstract class CommEngine extends HttpServlet
      * @param out
      */
     protected void configure(HttpServletRequest request, PrintWriter out) {
-    	JSONObject currConfig = getConfigJSON();
+    	// save original configuration for roll back in case of error
+    	JSONObject origConfigJSON = getConfigJSON();
     	
     	String jsonString = request.getParameter("data");
     	try {
@@ -558,9 +582,9 @@ public abstract class CommEngine extends HttpServlet
 		} catch (Exception e) {
 			myLogger.error(e);
 			out.write("Error - " + e.getMessage());
-			// restore to original confiuration
+			// restore current confiuration
 			try {
-				configure(currConfig);
+		    	configure(origConfigJSON);
 			} catch (Exception e1) {
 				out.write("\nInternal error in restoring original configuration: " + e1.getMessage());
 			}
@@ -601,9 +625,19 @@ public abstract class CommEngine extends HttpServlet
             	broadcast.configure(broadcastConfig);
             }
         }
+        // derived class
+        configureChild(configuration);
     }
 
     /**
+     * Derived class updates itself from given configuration.
+     * @param configuration
+     */
+    protected void configureChild(JSONObject configuration)
+    {
+	}
+
+	/**
      * <CallEngine_status>
      *   status of each broadcast
      *   <calls><total>ttt</total><connected>nnn</connected>
@@ -656,6 +690,7 @@ public abstract class CommEngine extends HttpServlet
                 out.write(broadcast.mkStatusReport() + "\n");
             }
             out.write("<job_summary completed='" + getCompletedJobCount() + "' pending='" + getPendingJobCount() + "' active='" + getActiveJobCount() + "'/>\n");
+            out.write("<engine_clock><daily_pause>" + daily_pause + "</daily_pause><daily_resume>" + daily_resume + "</daily_resume></engine_clock>\n");
             out.write("</" + tag + ">");
         }
     }