Additions to the Direct API:

 * Add an example of a versioned api
 * Add some more docs to direct.py
 * Add Limited, an API limiting/versioning wrapper
 * Improve the formatting of the stack tool
 * Add support for volume and network services to the direct api

1 files changed, 33 insertions, 2 deletions

diff --git a/bin/nova-direct-api b/bin/nova-direct-api
index a2c9f1557..83ec72722 100755
--- a/bin/nova-direct-api
+++ b/bin/nova-direct-api
@@ -34,12 +34,14 @@ if os.path.exists(os.path.join(possible_topdir, 'nova', '__init__.py')):
 
 gettext.install('nova', unicode=1)
 
+from nova import compute
 from nova import flags
 from nova import log as logging
+from nova import network
 from nova import utils
+from nova import volume
 from nova import wsgi
 from nova.api import direct
-from nova.compute import api as compute_api
 
 
 FLAGS = flags.FLAGS
@@ -50,13 +52,42 @@ flags.DEFINE_flag(flags.HelpshortFlag())
 flags.DEFINE_flag(flags.HelpXMLFlag())
 
 
+# An example of an API that only exposes read-only methods.
+# In this case we're just limiting which methods are exposed.
+class ReadOnlyCompute(direct.Limited):
+    """Read-only Compute API."""
+
+    _allowed = ['get', 'get_all', 'get_console_output']
+
+
+# An example of an API that provides a backwards compatibility layer.
+# In this case we're overwriting the implementation to ensure
+# compatibility with an older version. In reality we would want the
+# "description=None" to be part of the actual API so that code
+# like this isn't even necessary, but this example shows what one can
+# do if that isn't the situation.
+class VolumeVersionOne(direct.Limited):
+    _allowed = ['create', 'delete', 'update', 'get']
+
+    def create(self, context, size, name):
+        self.proxy.create(context, size, name, description=None)
+
+
 if __name__ == '__main__':
     utils.default_flagfile()
     FLAGS(sys.argv)
     logging.setup()
 
-    direct.register_service('compute', compute_api.API())
+    direct.register_service('compute', compute.API())
+    direct.register_service('volume', volume.API())
+    direct.register_service('network', network.API())
     direct.register_service('reflect', direct.Reflection())
+
+    # Here is how we could expose the code in the examples above.
+    #direct.register_service('compute-readonly',
+    #                        ReadOnlyCompute(compute.API()))
+    #direct.register_service('volume-v1', VolumeVersionOne(volume.API()))
+
     router = direct.Router()
     with_json = direct.JsonParamsMiddleware(router)
     with_req = direct.PostParamsMiddleware(with_json)