added missing interface

org.springframework.integration.adapter/src/main/java/org/springframework/integration/adapter/ftp/FTPClientPool.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2002-2008 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.springframework.integration.adapter.ftp;
+
+import org.apache.commons.net.ftp.FTPClient;
+
+/**
+ * A pool of {@link FTPClient} instances. The pool can be used to control the
+ * number of open ftp connections and reuse these connections efficiently.
+ * @author Iwein Fuld
+ * 
+ */
+public interface FTPClientPool extends FTPClientFactory {
+
+	/**
+	 * Releases the client back to the pool. When calling this method the caller
+	 * is no longer responsible for the connection. The pool is free to do with
+	 * it as it sees fit, which means either recycling or disconnecting it most
+	 * probably.
+	 * 
+	 * The caller should NOT disconnect the client before calling this method.
+	 * 
+	 * The caller is NOT expected to use the client after calling this method.
+	 * Doing so can lead to unexpected behavior.
+	 * 
+	 * @param client
+	 */
+	void releaseClient(FTPClient client);
+
+}

org.springframework.integration.adapter/src/main/java/org/springframework/integration/adapter/ftp/QueuedFTPClientPool.java

@@ -35,7 +35,7 @@ import org.springframework.util.Assert;
  * 
  * @author Iwein Fuld
  */
-public class QueuedFTPClientPool {
+public class QueuedFTPClientPool implements FTPClientPool {
 
 	private static final int DEFAULT_POOL_SIZE = 5;