[RFC wayland 1/2] doc: Add a paragraph about the object creation guarantee

[Jonas Ådahl]

One of the principles of the Wayland protocol is that object creation
always succeeds. If the server for some reason cannot create a valid
object as a response to some request, this would typically be caused by
a protocol violation and in such cases the server will terminate the
client with an error event before the object would be created.

This seems not to have been documented elsewhere before except in a blog
post by Pekka Paalanen[0], so it would be good to have it somewhere in
the official documentation.

[0] http://ppaalanen.blogspot.tw/2014/07/wayland-protocol-design-object-lifespan.html

Signed-off-by: Jonas Ådahl <jadahl at gmail.com>
---
 doc/publican/sources/Protocol.xml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/doc/publican/sources/Protocol.xml b/doc/publican/sources/Protocol.xml
index 477063b..75bb5cd 100644
--- a/doc/publican/sources/Protocol.xml
+++ b/doc/publican/sources/Protocol.xml
@@ -267,6 +267,10 @@
       the ID N will not be used until N-1 has been used.  Any ID allocation
       algorithm that does not maintain this property is incompatible with
       the implementation in libwayland.
+
+      Object creation always succeeds unless the action causing the creation
+      is a protocol violation which would terminate the client with an error
+      event before the object would be created.
     </para>
   </section>
   <section id="sect-Protocol-Compositor">
-- 
2.1.4