--- a/lib/js/urweb.js	Thu Apr 16 13:00:40 2009 -0400
+++ b/lib/js/urweb.js	Thu Apr 16 13:47:20 2009 -0400
@@ -23,6 +23,79 @@
 }
 
 
+// Error handling
+
+function whine(msg) {
+  alert(msg);
+  throw msg;
+}
+
+function pf() {
+  whine("Pattern match failure");
+}
+
+function runHandlers(ls, arg) {
+  for (; ls; ls = ls.next)
+    try {
+      ls.data(arg)(null);
+    } catch (v) { }
+}
+
+var errorHandlers = null;
+
+function onError(f) {
+  errorHandlers = cons(f, errorHandlers);
+}
+
+function er(s) {
+  runHandlers(errorHandlers, s);
+  throw {uw_error: s};
+}
+
+var failHandlers = null;
+
+function onFail(f) {
+  failHandlers = cons(f, failHandlers);
+}
+
+function doExn(v) {
+  if (v == null || v.uw_error == null) {
+    var s = (v == null ? "null" : v.toString());
+    runHandlers(failHandlers, s);
+  }
+}
+
+var disconnectHandlers = null;
+
+function onDisconnect(f) {
+  disconnectHandlers = cons(function (_){return f}, disconnectHandlers);
+}
+
+function discon() {
+  runHandlers(disconnectHandlers, null);
+}
+
+var connectHandlers = null;
+
+function onConnectFail(f) {
+  connectHandlers = cons(function (_){return f}, connectHandlers);
+}
+
+function conn() {
+  runHandlers(connectHandlers, null);
+}
+
+var serverHandlers = null;
+
+function onServerError(f) {
+  serverHandlers = cons(f, serverHandlers);
+}
+
+function servErr(s) {
+  runHandlers(serverHandlers, s);
+}
+
+
 // Embedding closures in XML strings
 
 function cs(f) {
@@ -90,19 +163,23 @@
 function populate(node) {
   var s = node.signal;
   var oldSources = node.sources;
-  var sr = s();
-  var newSources = sr.sources;
+  try {
+    var sr = s();
+    var newSources = sr.sources;
 
-  for (var sp = oldSources; sp; sp = sp.next)
-    if (!member(sp.data, newSources))
-      sp.data.dyns = remove(node, sp.data.dyns);
+    for (var sp = oldSources; sp; sp = sp.next)
+      if (!member(sp.data, newSources))
+        sp.data.dyns = remove(node, sp.data.dyns);
 
-  for (var sp = newSources; sp; sp = sp.next)
-    if (!member(sp.data, oldSources))
-      sp.data.dyns = cons(node, sp.data.dyns);
+    for (var sp = newSources; sp; sp = sp.next)
+      if (!member(sp.data, oldSources))
+        sp.data.dyns = cons(node, sp.data.dyns);
 
-  node.sources = newSources;
-  node.recreate(sr.data);
+    node.sources = newSources;
+    node.recreate(sr.data);
+  } catch (v) {
+    doExn(v);
+  }
 }
 
 function sc(v) {
@@ -160,7 +237,11 @@
     scriptsCopy[i] = scripts[i];
   for (var i = 0; i < len; ++i) {
     thisScript = scriptsCopy[i];
-    eval(thisScript.textContent);
+    try {
+      eval(thisScript.textContent);
+    } catch (v) {
+      doExn(v);
+    }
   }
 
   thisScript = savedScript;
@@ -227,7 +308,7 @@
   if (r.toString() == s)
     return r;
   else
-    throw "Can't parse int: " + s;
+    er("Can't parse int: " + s);
 }
 
 function pfl(s) {
@@ -235,7 +316,7 @@
   if (r.toString() == s)
     return r;
   else
-    throw "Can't parse float: " + s;
+    er("Can't parse float: " + s);
 }
 
 function uf(s) {
@@ -247,43 +328,6 @@
 }
 
 
-// Error handling
-
-function whine(msg) {
-  alert(msg);
-  throw msg;
-}
-
-function pf() {
-  whine("Pattern match failure");
-}
-
-var errorHandlers = null;
-
-function onError(f) {
-  errorHandlers = cons(f, errorHandlers);
-}
-
-function er(s) {
-  for (var ls = errorHandlers; ls; ls = ls.next)
-    ls.data(s)(null);
-  throw {uw_error: s};
-}
-
-var failHandlers = null;
-
-function onFail(f) {
-  failHandlers = cons(f, failHandlers);
-}
-
-function doExn(v) {
-  if (v == null || v.uw_error == null) {
-    var s = (v == null ? "null" : v.toString());
-    for (var ls = failHandlers; ls; ls = ls.next)
-      ls.data(s)(null);
-  }
-}
-
 
 // Remote calls
 
@@ -333,10 +377,14 @@
           isok = true;
       } catch (e) { }
 
-      if (isok)
-        k(parse(xhr.responseText));
-      else {
-        whine("Error querying remote server!");
+      if (isok) {
+        try {
+          k(parse(xhr.responseText));
+        } catch (v) {
+          doExn(v);
+        }
+      } else {
+        conn();
       }
     }
   };
@@ -406,8 +454,10 @@
 
       if (isok) {
         var lines = xhr.responseText.split("\n");
-        if (lines.length < 2) 
-          return; // throw "Empty message from remote server";
+        if (lines.length < 2) {
+          discon();
+          return;
+        }
 
         for (var i = 0; i+1 < lines.length; i += 2) {
           var chn = lines[i];
@@ -439,9 +489,9 @@
         connect();
       }
       else {
-        /*try {
-          whine("Error querying remote server for messages! " + xhr.status);
-        } catch (e) { }*/
+        try {
+          servError("Error querying remote server for messages: " + xhr.status);
+        } catch (e) { servError("Error querying remote server for messages"); }
       }
     }
   };