From 47f33da41913583452505a1b80fa2399e07f54e7 Mon Sep 17 00:00:00 2001
From: Steve Kille <Steve Kille>
Date: Fri, 4 Nov 2016 15:27:54 +0000
Subject: [PATCH] Add Marker IQ

---
 xep-0369.xml | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/xep-0369.xml b/xep-0369.xml
index c4202dd1..73a1b746 100644
--- a/xep-0369.xml
+++ b/xep-0369.xml
@@ -1656,6 +1656,32 @@ the participant is not be subscribed to all nodes associated with the channel (i
     For an active MIX Channel, the presence node is updated as channel participants change status and presence information is sent to the channel.  When a MIX channel starts, typically when the associated MIX Service and Server start, there is a need to initialize the presence node.    This is done by the XMPP server associated with the MIX channel sending out a presence probe for each channel participant, following the presence probe process specified in &rfc6121;.   A presence probe MUST NOT be sent for users who have set presence preference to not sharing.
   </p>
 </section2>
+  
+  <section2 topic="Ensuring Message Delivery" anchor="use-ensure-delivery">
+    <p>
+      It is important that messages are all transferred from the MIX channel to the server associated with the each channel participant.   Transfer between servers will typically happen quickly and &xep0198; will deal with short connection failures between servers.   Longer connection failures could lead to message loss.  This would lead to online users (who remain connected to their servers) missing messages, and to messages being missed out of the user archive.  This section describes how MIX addresses this.
+    </p>
+    <p>
+      When there is a long term connection failure, the MIX channel will receive an error from the XMPP server indicating that a message failed to transfer to a recipient.   When this happens, the MIX channel must take responsibility to ensure that the message is retransmitted and delivered.   When the MIX channel detects a failure it will make use of an IQ Marker message to determine when the connection to the peer server is working again.  Once the channel has received a response to the marker IQ it will retransmit the pending messages.   
+    </p>
+    
+    <example caption="Channel Sends Marker Message" ><![CDATA[
+ <iq from='coven@mix.shakespeare.example'
+    id='lx09df27'
+    to='hag66@shakespeare.example'
+    type='get'>
+  <marker xmlns='urn:xmpp:mix:0'/>
+</iq>
+
+
+<iq from='hag66@shakespeare.example'
+    id='lx09df27'
+    to='coven@mix.shakespeare.example'
+    type='result'>
+ <marker xmlns='urn:xmpp:mix:0'/>
+</iq>
+]]></example>
+  </section2>
 
   <section2 topic="Use of MAM" anchor="use-mam">
    <p>