--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/src/jdk.jshell/share/classes/jdk/jshell/spi/ExecutionControl.java	Sat May 21 22:32:08 2016 -0700
@@ -0,0 +1,154 @@
+/*
+ * Copyright (c) 2016, 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 jdk.jshell.spi;
+
+import java.util.Collection;
+import jdk.jshell.JShellException;
+
+/**
+ * This interface specifies the functionality that must provided to implement
+ * a pluggable JShell execution engine.
+ * <p>
+ * The audience for this Service Provider Interface is engineers
+ * wishing to implement their own version of the execution engine in support
+ * of the JShell API.  This is NOT a part of the JShell API.
+ * <p>
+ * A Snippet is compiled into code wrapped in a 'wrapper class'.  The execution
+ * engine is used by the core JShell implementation to load and, for
+ * executable Snippets, execute the Snippet.
+ * <p>
+ * Methods defined in this interface should only be called by the core JShell
+ * implementation.
+ * <p>
+ * To install an instance of ExecutionControl, it is passed to
+ * {@link jdk.jshell.JShell.Builder#executionEngine(jdk.jshell.spi.ExecutionControl) }.
+ */
+public interface ExecutionControl {
+
+    /**
+     * Represents the current status of a class in the execution engine.
+     */
+    public enum ClassStatus {
+        /**
+         * Class is not known to the execution engine (not loaded).
+         */
+        UNKNOWN,
+
+        /**
+         * Class is loaded, but the loaded/redefined bytes do not match those
+         * returned by {@link ExecutionEnv#getClassBytes(java.lang.String) }.
+         */
+        NOT_CURRENT,
+
+        /**
+         * Class is loaded and loaded/redefined bytes match those
+         * returned by {@link ExecutionEnv#getClassBytes(java.lang.String) }.
+         */
+        CURRENT
+    };
+
+    /**
+     * Initializes the instance. No methods in this interface can be called
+     * before this.
+     *
+     * @param env the execution environment information provided by JShell
+     * @throws Exception if the instance is unable to initialize
+     */
+    void start(ExecutionEnv env) throws Exception;
+
+    /**
+     * Shuts down this execution engine. Implementation should free all
+     * resources held by this execution engine.
+     * <p>
+     * No calls to methods on this interface should be made after close.
+     */
+    void close();
+
+    /**
+     * Adds the path to the execution class path.
+     *
+     * @param path the path to add
+     * @return true if successful
+     */
+    boolean addToClasspath(String path);
+
+    /**
+     * Invokes an executable Snippet by calling a method on the specified
+     * wrapper class. The method must have no arguments and return String.
+     *
+     * @param classname the class whose method should be invoked
+     * @param methodname the name of method to invoke
+     * @return the result of the execution or null if no result
+     * @throws JShellException if a user exception if thrown,
+     * {@link jdk.jshell.EvalException EvalException} will be thrown; if an
+     * unresolved reference is encountered,
+     * {@link jdk.jshell.UnresolvedReferenceException UnresolvedReferenceException}
+     * will be thrown
+     */
+    String invoke(String classname, String methodname) throws JShellException;
+
+    /**
+     * Attempts to load new classes. Class bytes are retrieved from
+     * {@link ExecutionEnv#getClassBytes(java.lang.String) }
+     *
+     * @param classes list of class names to load
+     * @return true if load succeeded
+     */
+    boolean load(Collection<String> classes);
+
+    /**
+     * Attempts to redefine previously loaded classes. Class bytes are retrieved
+     * from {@link ExecutionEnv#getClassBytes(java.lang.String) }
+     *
+     * @param classes list of class names to redefine
+     * @return true if redefine succeeded
+     */
+    boolean redefine(Collection<String> classes);
+
+    /**
+     * Queries if the class is loaded and the class bytes are current.
+     *
+     * @param classname name of the wrapper class to query
+     * @return {@code UNKNOWN} if the class is not loaded; {@code CURRENT} if
+     * the loaded/redefined bytes are equal to the most recent bytes for this
+     * wrapper class; otherwise {@code NOT_CURRENT}
+     */
+    ClassStatus getClassStatus(String classname);
+
+    /**
+     * Interrupt a running invoke.
+     */
+    void stop();
+
+    /**
+     * Returns the value of a variable.
+     *
+     * @param classname the name of the wrapper class of the variable
+     * @param varname the name of the variable
+     * @return the value of the variable
+     */
+    String varValue(String classname, String varname);
+}