doc: add session WG meeting

doc/meetings/2017-02-21-sessions.md

@@ -0,0 +1,48 @@
+# Sessions WG meeting
+
+Date: 2017-02-21
+
+Invited:
+
+ * Alexey Orlenko <eaglexrlnk@gmail.com>
+   ([@aqrln](https://github.com/aqrln)) from server team
+ * Mykola Bilochub <nbelochub@gmail.com>
+   ([@belochub](https://github.com/belochub)) from server team
+ * Denys Otrishko <shishugi@gmail.com>
+   ([@lundibundi](https://github.com/lundibundi)) from Android team
+ * Andrew Vysotskyi <firemaaaan@gmail.com>
+   ([@Gagnant](https://github.com/Gagnant)) from iOS team
+
+Present:
+
+ * Alexey Orlenko <eaglexrlnk@gmail.com>
+   ([@aqrln](https://github.com/aqrln)) from server team
+ * Mykola Bilochub <nbelochub@gmail.com>
+   ([@belochub](https://github.com/belochub)) from server team
+ * Denys Otrishko <shishugi@gmail.com>
+   ([@lundibundi](https://github.com/lundibundi)) from Android team
+
+Agenda:
+
+ * General way of reconnection to existing sessions;
+ * Session restoration mechanisms architecture;
+ * The problems with reconnection mobile developers encountered in our last
+   project and proper ways to solve them;
+ * Handshake packet formats (for request and response) that will be used to
+   implement reconnection to existing sessions.
+
+Conclusions:
+
+ * To make packet numbers unique for every session, not connection like it was before;
+ * To send total count of packets sent and received by each side during the session
+   in handshake packet, like this:
+
+   ```javascript
+   { handshake:[0, 'appName'], session: ['sessionId', sent_count, received_count] }
+   ```
+
+   and answer
+
+   ```javascript
+   { handshake:[0], ok: [sent_count, received_count] }
+   ```