--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/truffle/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/Instrument.java	Sun Sep 27 21:34:39 2015 -0700
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2013, 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.api.instrument;
+
+/**
+ * A <em>binding</em> between:
+ * <ol>
+ * <li>Some source of <em>execution events</em> in an executing Truffle AST, and</li>
+ * <li>A <em>listener</em>: a consumer of execution events on behalf of an external client.
+ * </ol>
+ * <p>
+ * Client-oriented documentation for the use of Instruments is available online at <a
+ * HREF="https://wiki.openjdk.java.net/display/Graal/Listening+for+Execution+Events" >https://
+ * wiki.openjdk.java.net/display/Graal/Listening+for+Execution+Events</a>
+ *
+ * @See Instrumenter
+ */
+abstract class Instrument {
+
+    protected Instrument() {
+    }
+
+    /**
+     * Removes this from its source of execution events and renders itself Instrument inert.
+     *
+     * @throws IllegalStateException if this has already been disposed
+     */
+    public abstract void dispose() throws IllegalStateException;
+
+    /**
+     * Has this been detached from its source of execution events.
+     */
+    public abstract boolean isDisposed();
+
+}