From 08fa853fca1706a9bc69edd62188d5d4e8f322de Mon Sep 17 00:00:00 2001
From: Nick Martin <nim@meteor.com>
Date: Tue, 7 Feb 2012 15:57:17 -0800
Subject: [PATCH] Implement Live Data protocol: 'connect' and 'connected'.

For now, high-level behavior is the same.  When the transport
disconnects, client doesn't attempt to reuse previous session.

Server always establishes a new Live Data session with each connect.
Server does not support method reply cache, and won't honor a client's
attempt to reuse a previous Live Data session id.
---
 packages/livedata/livedata_client.js | 15 ++++++++++-----
 packages/livedata/livedata_server.js |  9 ++++++++-
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/packages/livedata/livedata_client.js b/packages/livedata/livedata_client.js
index 3f5fddc707..974a90f8f2 100644
--- a/packages/livedata/livedata_client.js
+++ b/packages/livedata/livedata_client.js
@@ -38,6 +38,7 @@ if (typeof Meteor === "undefined") Meteor = {};
   });
 
   var livedata_connected = function (msg) {
+    Meteor._debug("CONNECTED", msg);
   };
 
   var livedata_data = function (msg) {
@@ -87,13 +88,17 @@ if (typeof Meteor === "undefined") Meteor = {};
   });
 
   Meteor._stream.reset(function (msg_list) {
-    // remove existing subscribe and unsubscribe
-    msg_list = _.reject(msg_list, function (elem) {
-      return (!elem
-              || (elem[0] === "livedata" && elem[1]
-                  && (elem[1].msg === "sub" || elem[1].msg === "unsub")));
+    // remove all 'livedata' message except 'method'
+    msg_list = _.filter(msg_list, function (elem) {
+      return (elem && (elem[0] !== "livedata" ||
+                       (elem[1] && elem[1].msg === "method")));
     });
 
+    // Send a connect message at the beginning of the stream.
+    // NOTE: reset is called even on the first connection, so this is
+    // the only place we send this message.
+    msg_list.unshift(['livedata', {msg: 'connect'}]);
+
     // add new subscriptions at the end. this way they take effect after
     // the handlers and we don't see flicker.
     subs.find().forEach(function (sub) {
diff --git a/packages/livedata/livedata_server.js b/packages/livedata/livedata_server.js
index 938a4795a0..87302bd843 100644
--- a/packages/livedata/livedata_server.js
+++ b/packages/livedata/livedata_server.js
@@ -119,6 +119,11 @@ if (typeof Meteor === "undefined") Meteor = {};
     }).run();
   };
 
+  var livedata_connect = function (socket, msg) {
+    // Always start a new session. We don't support any reconnection.
+    socket.emit('livedata', {msg: 'connected', session: Meteor.uuid()});
+  };
+
   var livedata_sub = function (socket, msg) {
     if (!publishes[msg.name]) {
       // can't sub to unknown publish name
@@ -195,7 +200,9 @@ if (typeof Meteor === "undefined") Meteor = {};
         return;
       }
 
-      if (msg.msg === 'sub')
+      if (msg.msg === 'connect')
+        livedata_connect(socket, msg);
+      else if (msg.msg === 'sub')
         livedata_sub(socket, msg);
       else if (msg.msg === 'unsub')
         livedata_unsub(socket, msg);