short snippet of doc multiserver mode. also added check for unique en…

…gine.name during startup.

symmetric/symmetric-assemble/src/docbook/advanced-topics.xml

@@ -998,5 +998,25 @@ Enter key password for <sym>
             basic authentication is setup with the standard configuration in the WEB.xml file. 
         </para>
     </section>
-
+    <section id="multi-server">
+        <title>Multi-Server Mode</title>
+        <para>
+            SymmetricDS supports running multiple SymmetricDS instances that leverage the same web server in the same
+            process.  This mode can be turned on in the <code>web/WEB-INF/web.xml</code> file.  By default, <code>multiServerMode</code>
+            is turned off. 
+        </para>
+            <programlisting>
+<![CDATA[    <context-param>
+        <param-name>multiServerMode</param-name>
+        <param-value>true</param-value>
+    </context-param>
+]]></programlisting>
+        <para>
+            When <code>multiServerMode</code> is turned on, SymmetricDS will initialize itself with an instance of 
+            a node for each properties file found in the <code>engines</code> directory.  Each node will inherit 
+            common properties from <code>conf/symmetric.properties</code>.   Each properties file must specify the 
+            minimum required properties to define a single node.  In addition, the properties file is required to also specify
+            a property, <code>engine.name</code>, that provides a unique name for the node's engine.  
+        </para>        
+    </section>    
 </chapter>

symmetric/symmetric-core/src/main/java/org/jumpmind/symmetric/SymmetricEngineHolder.java

@@ -31,15 +31,15 @@
 
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.lang.StringUtils;
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
 import org.jumpmind.symmetric.common.Constants;
 import org.jumpmind.symmetric.common.ParameterConstants;
+import org.jumpmind.symmetric.common.logging.ILog;
+import org.jumpmind.symmetric.common.logging.LogFactory;
 import org.jumpmind.symmetric.service.IRegistrationService;
 
 public class SymmetricEngineHolder {
 
-    final Log log = LogFactory.getLog(getClass());
+    final ILog log = LogFactory.getLog(getClass());
 
     private Map<String, ISymmetricEngine> engines = new HashMap<String, ISymmetricEngine>();
 
@@ -109,11 +109,15 @@ protected ISymmetricEngine create(String propertiesFile) {
             }
             engine = new StandaloneSymmetricEngine(null, propertiesFile);
             if (engine != null) {
-                engines.put(engine.getEngineName(), engine);
+                if (!engines.containsKey(engine.getEngineName())) {
+                    engines.put(engine.getEngineName(), engine);
+                } else {
+                    log.error("SymmetricEngineDuplicateName", engine.getEngineName());
+                }
             }
             return engine;
         } catch (Exception e) {
-            log.error(e, e);
+            log.error(e);
             return null;
         }
     }

symmetric/symmetric-core/src/main/resources/symmetric-messages.properties

@@ -265,6 +265,7 @@ SymmetricDSUpgradeFailed=The upgrade failed.  The system may be unstable.  Pleas
 SymmetricDSUpgradeNeeded=Upgrade of node is necessary.  Please set the auto.upgrade property to true for an automated upgrade.
 SymmetricDSManualUpgradeNeeded=A manual upgrade of the node is required.  Can not automatically upgrade from version %s to version %s.
 SymmetricEngineMissing=Could not find a reference to the SymmetricEngine from %s
+SymmetricEngineDuplicateName=An engine with the name of %s was not started because an engine of the same name has already been started.  Please set the engine.name property in the properties file to a unique name.
 SymmetricEngineNotRegistered=Did not run the %s job because the engine is not registered.
 SymmetricEngineNotStarted=The engine is not currently started.
 SyncDisabled=Synchronization is disabled on the server node.