From e587a11049129866bf3fd6db0a0f72d44ad6b39f Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Mon, 21 Sep 2026 21:26:03 -0700
Subject: Change protocol between compiler and browser

---
 .../java/com/seaofnodes/simple/print/JSViewer.java | 24 +++++++++++++----
 .../seaofnodes/simple/print/SimpleWebSocket.java   | 30 +++++++++++-----------
 2 files changed, 34 insertions(+), 20 deletions(-)

(limited to 'chapter25/src/main/java')

diff --git a/chapter25/src/main/java/com/seaofnodes/simple/print/JSViewer.java b/chapter25/src/main/java/com/seaofnodes/simple/print/JSViewer.java
index 156f1fe9..a9f6bfd4 100644
--- a/chapter25/src/main/java/com/seaofnodes/simple/print/JSViewer.java
+++ b/chapter25/src/main/java/com/seaofnodes/simple/print/JSViewer.java
@@ -1,5 +1,6 @@
 package com.seaofnodes.simple.print;
 
+import com.seaofnodes.graph.GraphJson;
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.type.*;
@@ -11,8 +12,10 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.net.URI;
 import java.util.Collection;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Stack;
+import java.util.UUID;
 import static com.seaofnodes.simple.codegen.CodeGen.CODE;
 
 public class JSViewer implements AutoCloseable {
@@ -28,7 +31,9 @@ public class JSViewer implements AutoCloseable {
     // WebSocket to the browser for display
     static SimpleWebSocket SERVER;
 
-    static int N;               // Dot frames
+    static long N;              // Snapshot step within this compilation
+    static String COMP;
+    static final SimpleGraphAdapter GRAPH = new SimpleGraphAdapter();
 
     JSViewer() throws Exception {
         // Launch server; handshake
@@ -60,6 +65,7 @@ public class JSViewer implements AutoCloseable {
                 System.out.println(src);
                 try {
                     N=0;
+                    COMP = UUID.randomUUID().toString();
                     // Use parser scope, xscope when building views
                     CodeGen code = new CodeGen(src);
                     SHOW = true;
@@ -93,10 +99,19 @@ public class JSViewer implements AutoCloseable {
             return;
         boolean midParse = CODE._phase == CodeGen.Phase.Parse;
         Stack<ScopeNode> xScopes = midParse ? CODE.P._xScopes : null;
+        var roots = new ArrayList<Node>();
+        roots.add(CODE._stop);
+        if( midParse ) {
+            roots.add(CODE.P._scope);
+            roots.addAll(xScopes);
+        }
+        long step = N++;
+        var snap = GRAPH.snap(COMP, step, roots.toArray(Node[]::new));
+        int pos = midParse ? CODE.P.pos() : -1;
 
         Collection<Node> all = GraphVisualizer.findAll(xScopes, CODE._stop, midParse ? CODE.P._scope: null);
         SB sb = new SB();
-        sb.p("digraph view_").p(N++).p(" {\n").ii();
+        sb.p("digraph view_").p(step).p(" {\n").ii();
         if( midParse )
             sb.i().p("// POS: ").p(CODE.P.pos()).nl();
 
@@ -139,11 +154,10 @@ public class JSViewer implements AutoCloseable {
 
 
         sb.p("}\n").di();
-        // Tell client another DOT frame
+        // Send the model and its current DOT rendering as one playback frame.
         String dot = sb.toString();
-        System.out.println(dot);
         try {
-            SERVER.put(dot);
+            SERVER.put(GraphJson.frame(snap, pos, dot));
         } catch( IOException ioe ) {
             try { SERVER.close();} catch( IOException ignored ){}
         }
diff --git a/chapter25/src/main/java/com/seaofnodes/simple/print/SimpleWebSocket.java b/chapter25/src/main/java/com/seaofnodes/simple/print/SimpleWebSocket.java
index d7fa8bf2..ae500879 100644
--- a/chapter25/src/main/java/com/seaofnodes/simple/print/SimpleWebSocket.java
+++ b/chapter25/src/main/java/com/seaofnodes/simple/print/SimpleWebSocket.java
@@ -139,7 +139,7 @@ class SimpleWebSocket extends ServerSocket {
             for( int i=0; i<len; i++ )
                 _str[i] = (byte)(rawget() ^ _key[i & 3]);
 
-            return new String(_str,0,len);
+            return new String(_str,0,len,StandardCharsets.UTF_8);
         }
             // Client closes
         case 8: return null;
@@ -155,24 +155,24 @@ class SimpleWebSocket extends ServerSocket {
         }
     }
 
-    // Classic put to browser client.  No encoding.
+    // Server text frames are UTF-8 and unmasked.
     public void put(String msg) throws IOException {
-        int len = msg.length();
+        byte[] bytes = msg.getBytes(StandardCharsets.UTF_8);
+        int len = bytes.length;
+        _out.write(129); // FIN, opcode 1 - whole text message
         if( len <= 125 ) {
-            _out.write(129); // FIN, opcode 1 - whole text message
             _out.write(len);
-            for( int i=0; i<msg.length(); i++ )
-                _out.write(msg.charAt(i));
-            return;
+        } else if( len <= 65535 ) {
+            _out.write(126);
+            _out.write(len>>>8);
+            _out.write(len&255);
+        } else {
+            _out.write(127);
+            for( int shift = 56; shift >= 0; shift -= 8 )
+                _out.write((int)((long)len >>> shift) & 255);
         }
-        if( len > 65535 )
-            throw Utils.TODO("MOAR LENGTH");
-        _out.write(129);        // FIN, opcode 1 - whole text message
-        _out.write(126);        // Length is 16b
-        _out.write(len>>>8);
-        _out.write(len&255);
-        for( int i=0; i<msg.length(); i++ )
-            _out.write(msg.charAt(i));
+        _out.write(bytes);
+        _out.flush();
     }
 
     @Override public void close() throws IOException {
-- 
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