--- a/truffle/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/package-info.java	Mon Sep 21 17:03:27 2015 -0700
+++ b/truffle/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/package-info.java	Mon Sep 21 21:21:29 2015 -0700
@@ -24,7 +24,175 @@
  */
 
 /**
- * Advanced node manipulation instruments.
+ * <h4>The Truffle Instrumentation Framework</h4>
+ * <p>
+ * This framework permits client
+ * {@linkplain com.oracle.truffle.api.iknstrument.Instrumenter.Tool tools},
+ * either builtin or third-party, to observe with <em>very low overhead</em> the execution of a
+ * {@linkplain com.oracle.truffle.api.TruffleLanguage Truffle Language} program at the level of
+ * <em>AST execution events</em>:
+ * <ul>
+ * <li>a Truffle
+ * {@linkplain com.oracle.truffle.api.nodes.Node Node} is about to be executed, or</li>
+ * <li>a Truffle
+ * {@linkplain com.oracle.truffle.api.nodes.Node Node} execution has just completed.</li>
+ * </ul>
+ * The framework supports many kinds of tools, for example simple collectors of data such as
+ * {@linkplain com.oracle.truffle.tools.CoverageTracker code coverage}.
+ * It also supports Truffle's built-in
+ * {@linkplain com.oracle.truffle.api.debug.Debugger debugging services}, as well as utilities
+ * that maintain {@linkplain com.oracle.truffle.tools.LineToProbesMap maps of source code locations}
+ * for other tools such as {@linkplain com.oracle.truffle.api.debug.Debugger debugging}.
+ *
+ * <h4>Instrumentation Services</h4>
+ * <p>
+ * API access to instrumentation services is provided by the
+ * {@linkplain com.oracle.truffle.api.instrument.Instrumenter Instrumenter} that is part of
+ * the Truffle execution environment. These services fall into several categories:
+ *
+ * <ul>
+ *
+ * <li><strong>AST Markup: probing</strong>
+ * <ul>
+ * <li>Execution events can only be observed at AST locations that have been
+ * {@linkplain com.oracle.truffle.api.instrument.Instrumenter#probe(com.oracle.truffle.api.nodes.Node) probed},
+ * which results in the creation of a
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probe} that is permanently associated with a
+ * particular segment of source code, e.g. a "statement", that corresponds to an AST location.</li>
+ * <li>Probing is only supported at
+ * {@linkplain com.oracle.truffle.api.nodes.Node Nodes} that are implemented to be
+ * {@linkplain com.oracle.truffle.api.instrument.Instrumenter#isInstrumentable(com.oracle.truffle.api.nodes.Node)
+ * instrumentable}.</li>
+ * <li>The relationship between a
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probe} and
+ * a source code location persists across Truffle <em>cloning</em> of ASTs, which is to say, a single
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probe} corresponds to (and keeps track of)
+ * the equivalent location in every clone of the original AST.</li>
+ * <li>Probing is specified by
+ * {@linkplain com.oracle.truffle.api.instrument.Instrumenter#registerASTProber(ASTProber) registering}
+ * an instance of
+ * {@linkplain com.oracle.truffle.api.instrument.ASTProber ASTProber}.
+ * A default prober provided by each {@linkplain com.oracle.truffle.api.TruffleLanguage TruffelLanguage}
+ * will be registered automatically.</li>
+ * <li>All AST probing must be complete before any AST execution has started.</li>
+ * </ul></li>
+ *
+ * <li><strong>AST Markup: tagging</strong>
+ * <ul>
+ * <li>Additional information can be added at any time to a
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probe} by
+ * {@linkplain com.oracle.truffle.api.instrument.Probe#tagAs(SyntaxTag, Object) adding} to its set of
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTag tags}.</li>
+ *
+ * <li>{@linkplain com.oracle.truffle.api.instrument.StandardSyntaxTag Standard tags} should
+ * be used for common, language-agnostic concepts such as
+ * {@linkplain com.oracle.truffle.api.instrument.StandardSyntaxTag#STATEMENT STATEMENT}, and this
+ * is usually done by each language's default
+ * {@linkplain com.oracle.truffle.api.instrument.ASTProber ASTProber} while
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probes} are being created.</li>
+ * <li>{@linkplain com.oracle.truffle.api.instrument.SyntaxTag Tags} serve to configure the behavior
+ * of clients during program execution.  For example, knowing which
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probes} are on
+ * {@linkplain com.oracle.truffle.api.instrument.StandardSyntaxTag#STATEMENT STATEMENT nodes}
+ * informs both the {@linkplain com.oracle.truffle.tools.CoverageTracker code coverage} counter
+ * and the
+ * {@linkplain com.oracle.truffle.api.debug.Debugger debugger} while "stepping".</li>
+ * <li>{@linkplain com.oracle.truffle.api.instrument.SyntaxTag tags} can also be added at any
+ * time by any client for any purpose, including private
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTag Tags} about which other clients
+ * can learn nothing.</li>
+ * </ul></li>
+ *
+ * <li><strong>Markup Discovery: finding probes</strong>
+ * <ul>
+ * <li>Clients can be observe {@linkplain com.oracle.truffle.api.instrument.Probe Probes}
+ * being {@linkplain com.oracle.truffle.api.instrument.Instrumenter#probe(com.oracle.truffle.api.nodes.Node) created} and
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTag Tags} being
+ * {@linkplain com.oracle.truffle.api.instrument.Probe#tagAs(SyntaxTag, Object) added} by
+ * {@linkplain com.oracle.truffle.api.instrument.Instrumenter#addProbeListener(ProbeListener) registering a
+ * {@linkplain com.oracle.truffle.api.instrument.ProbeListener ProbeListner}.</li>
+ * <li>Clients can also
+ * {@linkplain com.oracle.truffle.api.instrument.Instrumenter#findProbesTaggedAs(SyntaxTag) find} all existing
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probes}, possibly filtering the search by
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTag tag}.</li>
+ * </ul></li>
+ *
+ * <li><strong>Observing Execution: event listening:</strong>
+ * <ul>
+ * <li>Clients can be notified of <em>AST execution events</em> by creating one of several kinds of
+ * <em>event listener</em> and <em>attaching</em> it to a
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probe}. This creates an
+ * {@linkplain com.oracle.truffle.api.instrument.Instrument Instrument} that notifies the listener
+ * of every subsequent execution event at the AST location corresponding to the
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probe}.</li>
+ * <li>An
+ * {@linkplain com.oracle.truffle.api.instrument.Instrument Instrument} can be
+ * {@linkplain com.oracle.truffle.api.instrument.Instrument#dispose() disposed}, at which time
+ * it is removed from service at every clone of the AST, incurs no further overhead, and is
+ * permanently unusable.</li>
+ * <li>Many clients need only implement a
+ * {@linkplain com.oracle.truffle.api.instrument.SimpleInstrumentListener SimpleInstrumentListener},
+ * whose notification methods provide only the instance of the
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probe} to which it was attached.  This
+ * provides access to the corresponding
+ * {@linkplain com.oracle.truffle.api.SourceSection source code location} and any
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTag tags} that had been applied there.</li>
+ * <li>Clients that require deeper access to execution state implement a
+ * {@linkplain com.oracle.truffle.api.instrument.StandardInstrumentListener StandardInstrumentListener}
+ * whose notification methods provide access to the concrete
+ * {@linkplain com.oracle.truffle.api.nodes.Node AST location} and current
+ * {@linkplain com.oracle.truffle.api.frame.Frame stack frame}.</li>
+ * <li>Clients can also create an
+ * {@linkplain com.oracle.truffle.api.instrument.Instrument Instrument} (whose design is currently
+ * under revision) that supports (effectively) inserting a Truffle AST fragment into the AST
+ * location, where it will be executed subject to full Truffle optimization.</li>
+ * </ul></li>
+ *
+ * <li><strong>Wide-area Instrumentation: traps</strong>
+ * <ul>
+ * <li>A specialized form of Instrumentation is provided that efficiently attaches a single
+ * listener called a
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTagTrap tag trap} to every
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probe} containing a specified
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTag tag}.</li>
+ * <li>One (but no more than one)
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTagTrap tag trap} may optionally be set
+ * to be notified <em>before</em> every <em>AST execution event</em> where the specified
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTag tag} is present.</li>
+ * <li>One (but no more than one)
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTagTrap tag trap} may optionally be set
+ * to be notified <em>after</em> every <em>AST execution event</em> where the specified
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTag tag} is present.</li>
+ * <li>The
+ * {@linkplain com.oracle.truffle.api.instrument.SyntaxTagTrap tag trap} mechanism is independent
+ * of listeners that may be attached to
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probe}.  It is especially valuable for
+ * applications such as the debugger, where during "stepping" the program should be halted at
+ * any node tagged with
+ * {@linkplain com.oracle.truffle.api.instrument.StandardSyntaxTag#STATEMENT STATEMENT}.</li>
+ * </ul></li>
+ *
+ * <li><strong>Data Gathering Utilities:  tools</strong>
+ * <ul>
+ * <li>The Instrumentation Framework supports extensible set of utilities that can be
+ * {@linkplain com.oracle.truffle.api.instrument.Instrumenter#install(com.oracle.truffle.api.instrument.Instrumenter.Tool)
+ * installed}, at which time they start collecting information that can be queried at any time.</li>
+ * <li>Once installed, these
+ * {@linkplain com.oracle.truffle.api.instrument.Instrumenter.Tool tools} can be dynamically
+ * {@linkplain com.oracle.truffle.api.instrument.Instrumenter.Tool#setEnabled(boolean) disabled and re-enabled} and eventually
+ * {@linkplain com.oracle.truffle.api.instrument.Instrumenter.Tool#dispose() disposed} when no longer needed.</li>
+ * <li>A useful example is the
+ * {@linkplain com.oracle.truffle.tools.LineToProbesMap LineToProbesMap}, which incrementally builds and maintains a map of
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probes} indexed by
+ * {@linkplain com.oracle.truffle.api.source.LineLocation source code line}. Truffle
+ * {@linkplain com.oracle.truffle.api.debug.Debugger debugging services} depend heavily on this utility.</li>
+ * <li>The
+ * {@linkplain com.oracle.truffle.tools.CoverageTracker CoverageTracker} maintains counts of execution events where a
+ * {@linkplain com.oracle.truffle.api.instrument.Probe Probe} has been tagged with
+ * {@linkplain com.oracle.truffle.api.instrument.StandardSyntaxTag#STATEMENT STATEMENT}, indexed by source code line.</li>
+ * </ul></li>
+ * </ul>
+ *
  */
 package com.oracle.truffle.api.instrument;