--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.tools.debug.shell/src/com/oracle/truffle/tools/debug/shell/REPLServer.java	Tue May 26 16:38:13 2015 -0700
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.truffle.tools.debug.shell;
+
+/**
+ * The server side of a simple message-based protocol for a possibly remote language
+ * Read-Eval-Print-Loop.
+ */
+public interface REPLServer {
+
+    /**
+     * Starts up a server; status returned in a message.
+     */
+    REPLMessage start();
+
+    /**
+     * Ask the server to handle a request. Return a non-empty array of messages to simulate remote
+     * operation where the protocol has possibly multiple messages being returned asynchronously in
+     * response to each request.
+     */
+    REPLMessage[] receive(REPLMessage request);
+
+}