qmp: document strict parsing
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
diff --git a/QMP/qmp-spec.txt b/QMP/qmp-spec.txt
index 9d30a8c..1ba916c 100644
--- a/QMP/qmp-spec.txt
+++ b/QMP/qmp-spec.txt
@@ -209,13 +209,27 @@
capabilities array (section '2.2 Server Greeting'). Thus, Clients can check
that array and enable the capabilities they support.
-Additionally, Clients must not assume any particular:
+The QMP Server performs a type check on the arguments to a command. It
+generates an error if a value does not have the expected type for its
+key, or if it does not understand a key that the Client included. The
+strictness of the Server catches wrong assumptions of Clients about
+the Server's schema. Clients can assume that, when such validation
+errors occur, they will be reported before the command generated any
+side effect.
-- Size of json-objects or length of json-arrays
+However, Clients must not assume any particular:
+
+- Length of json-arrays
+- Size of json-objects; in particular, future versions of QEMU may add
+ new keys and Clients should be able to ignore them.
- Order of json-object members or json-array elements
- Amount of errors generated by a command, that is, new errors can be added
to any existing command in newer versions of the Server
+Of course, the Server does guarantee to send valid JSON. But apart from
+this, a Client should be "conservative in what they send, and liberal in
+what they accept".
+
6. Downstream extension of QMP
------------------------------
