[telepathy-spec/master] Observer: add some text from my email "Semantics of the ChannelDispatcher API"

[Simon McVittie]

---
 spec/Client_Observer.xml |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/spec/Client_Observer.xml b/spec/Client_Observer.xml
index c97de9c..de8bd31 100644
--- a/spec/Client_Observer.xml
+++ b/spec/Client_Observer.xml
@@ -78,6 +78,15 @@
         <tp:dbus-ref
           namespace="org.freedesktop.Telepathy.Channel">Requested</tp:dbus-ref>
         property.</p>
+
+      <p>Because it might take time for an observer to become ready (for
+        instance, a Text logger needs to wait until pending messages have been
+        downloaded), the channel dispatcher must wait (up to some timeout) for
+        all observers to return from
+        <tp:member-ref>ObserveChannels</tp:member-ref> before letting anything
+        destructive happen. Destructive things (e.g. acknowledging messages)
+        are defined to be done by handlers, therefore HandleWith and Claim
+        aren't allowed to succeed until all observers are ready.</p>
     </tp:docstring>
 
     <property name="ObserverChannelFilter"
-- 
1.5.6.5