RESOURCE_ATTRIBUTE_MAP = {    ‘myextensions‘: {        ‘id‘: {‘allow_post‘: False, ‘allow_put‘: False,               ‘is_visible‘: True},        ‘name‘: {‘allow_post‘: True, ‘allow_put‘: True,                          ‘is_visible‘: True},        ‘tenant_id‘: {‘allow_post‘: True, ‘allow_put‘: False,                      ‘validate‘: {‘type:string‘: None},                      ‘required_by_policy‘: True,                      ‘is_visible‘: True}        }    }

# The following is a short reference for understanding attribute info:# default: default value of the attribute (if missing, the attribute# becomes mandatory.# allow_post: the attribute can be used on POST requests.# allow_put: the attribute can be used on PUT requests.# validate: specifies rules for validating data in the attribute.# convert_to: transformation to apply to the value before it is returned# is_visible: the attribute is returned in GET responses.# required_by_policy: the attribute is required by the policy engine and# should therefore be filled by the API layer even if not present in# request body.# enforce_policy: the attribute is actively part of the policy enforcing# mechanism, ie: there might be rules which refer to this attribute.

from neutron.api import extensions
from neutron import manager
from neutron.api.v2 import base

class Myextension(extensions.ExtensionDescriptor):    # The name of this class should be the same as the file name    # The first letter must be changed from lower case to upper case     # There are a couple of methods and their properties defined in the    # parent class of this class, ExtensionDescriptor you can check them    @classmethod    def get_name(cls):        # You can coin a name for this extension        return "My Extension"        @classmethod    def get_alias(cls):        # This alias will be used by your core_plugin class to load        # the extension        return "my-extensions"    @classmethod    def get_description(cls):        # A small description about this extension        return "An extension defined by myself. Haha!"    @classmethod    def get_namespace(cls):        # The XML namespace for this extension        return "http://docs.openstack.org/ext/myextension/api/v1.0"    @classmethod    def get_updated(cls):        # Specify when was this extension last updated,        # good for management when there are changes in the design        return "2014-08-07T00:00:00-00:00"    @classmethod    def get_resources(cls):        # This method registers the URL and the dictionary  of        # attributes on the neutron-server.        exts = []        plugin = manager.NeutronManager.get_plugin()        resource_name = ‘myextension‘        collection_name = ‘%ss‘ % resource_name        params = RESOURCE_ATTRIBUTE_MAP.get(collection_name, dict())        controller = base.create_resource(collection_name, resource_name,                                          plugin, params, allow_bulk=False)        ex = extensions.ResourceExtension(collection_name, controller)        exts.append(ex)        return exts

class MyPlugin(db_base_plugin_v2.NeutronDbPluginV2):
　　...
　　supported_extension_aliases = [‘my-extensions‘]
　　
　　def __init__(self):
　　　　...
　　...