Add spec folder for Xena

Change-Id: I300ec5342988cae134e9d1d472684715ee7e9317

specs/index.rst

@@ -20,3 +20,4 @@
    ussuri/index
    victoria/index
    wallaby/index
+   xena/index

specs/xena/index.rst

@@ -0,0 +1,9 @@
+=======================
+ Xena Specifications
+=======================
+
+.. toctree::
+   :glob:
+   :maxdepth: 2
+
+   support-extra-specs-to-subscription-confirming

specs/xena/support-extra-specs-to-subscription-confirming.rst

@@ -0,0 +1,105 @@
+..
+  This template should be in ReSTructured text. The filename in the git
+  repository should match the launchpad URL, for example a URL of
+  https://blueprints.launchpad.net/zaqar/+spec/awesome-thing should be named
+  awesome-thing.rst.
+
+  Please do not delete any of the sections in this
+  template.  If you have nothing to say for a whole section, just write: None
+
+  For help with syntax, see http://sphinx-doc.org/rest.html
+  To test out your formatting, see http://www.tele3.cz/jbar/rest/rest.html
+
+==============================================
+Support Extra Specs to Subscription-confirming
+==============================================
+
+https://blueprints.launchpad.net/zaqar/+spec/support-extra-specs-to-subscription-confirming
+
+This requirement came from a true scenariowhen people use the subscription
+function of Zaqar, for example, text messages, they need to return some extra
+information like message authentication code in confirming process.
+Now Zaqar still cant support it, that will impact the usage of subscription.
+
+Problem description
+===================
+
+Currently, Zaqar can't support extra information in subscription
+confirming process. This will block user to input information that
+is needed when subcription is confirming. There is a true case that
+came from Zaqar's user. They want to input the message authentication
+code into Zaqar when the subscription is confirming, the code will be
+used to identify the subscriber. So Zaqar should support this kind of
+mechanism.
+
+Proposed change
+===============
+
+1. Introduce a key-value called "extra_spec" in confirming request body.
+
+2. Introduce a driver mechanism to let vendors to implement what they
+   want to do with extra_spec information.
+
+API Impact
+-----------
+
+Subscription confirming request:
+
+.. code-block::
+
+  PUT: /v2/subscriptions/subscription_id/confirm
+
+    RESPONSE CODE: 204
+    REQUEST BODY:
+    {
+      "confirmed": true,
+      "extra_spec": {"message_authentication_code": "xxxxxx"}
+    }
+
+Drawbacks
+---------
+
+None
+
+Alternatives
+------------
+
+None
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  wanghao <sxmatch1986@gmail.com>
+
+Secondary assignee:
+  None
+
+Milestones
+----------
+
+Target Milestone for completion:
+  wallaby M-2
+
+Work Items
+----------
+
+#. Modify api and transport code.
+#. Add driver mechanism to handler the extra spec.
+#. Add release note for this feature.
+#. Update API reference.
+#. Change unit, functional and tempest tests accordingly.
+#. Add client support.
+
+Dependencies
+============
+
+None
+
+References
+==========
+
+None