vmware-nsx/quantum/wsgi.py
2013-01-23 03:52:23 +00:00

1119 lines
39 KiB
Python

# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2011 OpenStack LLC.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Utility methods for working with WSGI servers
"""
import socket
import sys
from xml.dom import minidom
from xml.parsers import expat
import eventlet.wsgi
eventlet.patcher.monkey_patch(all=False, socket=True)
import routes.middleware
import webob.dec
import webob.exc
from quantum.common import exceptions as exception
from quantum import context
from quantum.openstack.common import jsonutils
from quantum.openstack.common import log as logging
LOG = logging.getLogger(__name__)
def run_server(application, port):
"""Run a WSGI server with the given application."""
sock = eventlet.listen(('0.0.0.0', port))
eventlet.wsgi.server(sock, application)
class Server(object):
"""Server class to manage multiple WSGI sockets and applications."""
def __init__(self, name, threads=1000):
self.pool = eventlet.GreenPool(threads)
self.name = name
def start(self, application, port, host='0.0.0.0', backlog=128):
"""Run a WSGI server with the given application."""
self._host = host
self._port = port
# TODO(dims): eventlet's green dns/socket module does not actually
# support IPv6 in getaddrinfo(). We need to get around this in the
# future or monitor upstream for a fix
try:
info = socket.getaddrinfo(self._host,
self._port,
socket.AF_UNSPEC,
socket.SOCK_STREAM)[0]
family = info[0]
bind_addr = info[-1]
self._socket = eventlet.listen(bind_addr,
family=family,
backlog=backlog)
except:
LOG.exception(_("Unable to listen on %(host)s:%(port)s") %
{'host': host, 'port': port})
sys.exit(1)
self._server = self.pool.spawn(self._run, application, self._socket)
@property
def host(self):
return self._socket.getsockname()[0] if self._socket else self._host
@property
def port(self):
return self._socket.getsockname()[1] if self._socket else self._port
def stop(self):
self._server.kill()
def wait(self):
"""Wait until all servers have completed running."""
try:
self.pool.waitall()
except KeyboardInterrupt:
pass
def _run(self, application, socket):
"""Start a WSGI server in a new green thread."""
logger = logging.getLogger('eventlet.wsgi.server')
eventlet.wsgi.server(socket, application, custom_pool=self.pool,
log=logging.WritableLogger(logger))
class Middleware(object):
"""
Base WSGI middleware wrapper. These classes require an application to be
initialized that will be called next. By default the middleware will
simply call its wrapped app, or you can override __call__ to customize its
behavior.
"""
@classmethod
def factory(cls, global_config, **local_config):
"""Used for paste app factories in paste.deploy config files.
Any local configuration (that is, values under the [filter:APPNAME]
section of the paste config) will be passed into the `__init__` method
as kwargs.
A hypothetical configuration would look like:
[filter:analytics]
redis_host = 127.0.0.1
paste.filter_factory = nova.api.analytics:Analytics.factory
which would result in a call to the `Analytics` class as
import nova.api.analytics
analytics.Analytics(app_from_paste, redis_host='127.0.0.1')
You could of course re-implement the `factory` method in subclasses,
but using the kwarg passing it shouldn't be necessary.
"""
def _factory(app):
return cls(app, **local_config)
return _factory
def __init__(self, application):
self.application = application
def process_request(self, req):
"""
Called on each request.
If this returns None, the next application down the stack will be
executed. If it returns a response then that response will be returned
and execution will stop here.
"""
return None
def process_response(self, response):
"""Do whatever you'd like to the response."""
return response
@webob.dec.wsgify
def __call__(self, req):
response = self.process_request(req)
if response:
return response
response = req.get_response(self.application)
return self.process_response(response)
class Request(webob.Request):
def best_match_content_type(self):
"""Determine the most acceptable content-type.
Based on:
1) URI extension (.json/.xml)
2) Content-type header
3) Accept* headers
"""
# First lookup http request
parts = self.path.rsplit('.', 1)
if len(parts) > 1:
format = parts[1]
if format in ['json', 'xml']:
return 'application/{0}'.format(parts[1])
#Then look up content header
type_from_header = self.get_content_type()
if type_from_header:
return type_from_header
ctypes = ['application/json', 'application/xml']
#Finally search in Accept-* headers
bm = self.accept.best_match(ctypes)
return bm or 'application/json'
def get_content_type(self):
allowed_types = ("application/xml", "application/json")
if not "Content-Type" in self.headers:
LOG.debug(_("Missing Content-Type"))
return None
type = self.content_type
if type in allowed_types:
return type
return None
@property
def context(self):
if 'quantum.context' not in self.environ:
self.environ['quantum.context'] = context.get_admin_context()
return self.environ['quantum.context']
class ActionDispatcher(object):
"""Maps method name to local methods through action name."""
def dispatch(self, *args, **kwargs):
"""Find and call local method."""
action = kwargs.pop('action', 'default')
action_method = getattr(self, str(action), self.default)
return action_method(*args, **kwargs)
def default(self, data):
raise NotImplementedError()
class DictSerializer(ActionDispatcher):
"""Default request body serialization"""
def serialize(self, data, action='default'):
return self.dispatch(data, action=action)
def default(self, data):
return ""
class JSONDictSerializer(DictSerializer):
"""Default JSON request body serialization"""
def default(self, data):
return jsonutils.dumps(data)
class XMLDictSerializer(DictSerializer):
def __init__(self, metadata=None, xmlns=None):
"""
:param metadata: information needed to deserialize xml into
a dictionary.
:param xmlns: XML namespace to include with serialized xml
"""
super(XMLDictSerializer, self).__init__()
self.metadata = metadata or {}
self.xmlns = xmlns
def default(self, data):
# We expect data to contain a single key which is the XML root.
root_key = data.keys()[0]
doc = minidom.Document()
node = self._to_xml_node(doc, self.metadata, root_key, data[root_key])
return self.to_xml_string(node)
def __call__(self, data):
# Provides a migration path to a cleaner WSGI layer, this
# "default" stuff and extreme extensibility isn't being used
# like originally intended
return self.default(data)
def to_xml_string(self, node, has_atom=False):
self._add_xmlns(node, has_atom)
return node.toxml('UTF-8')
#NOTE (ameade): the has_atom should be removed after all of the
# xml serializers and view builders have been updated to the current
# spec that required all responses include the xmlns:atom, the has_atom
# flag is to prevent current tests from breaking
def _add_xmlns(self, node, has_atom=False):
if self.xmlns is not None:
node.setAttribute('xmlns', self.xmlns)
if has_atom:
node.setAttribute('xmlns:atom', "http://www.w3.org/2005/Atom")
def _to_xml_node(self, doc, metadata, nodename, data):
"""Recursive method to convert data members to XML nodes."""
result = doc.createElement(nodename)
# Set the xml namespace if one is specified
# TODO(justinsb): We could also use prefixes on the keys
xmlns = metadata.get('xmlns', None)
if xmlns:
result.setAttribute('xmlns', xmlns)
#TODO(bcwaldon): accomplish this without a type-check
if isinstance(data, list):
collections = metadata.get('list_collections', {})
if nodename in collections:
metadata = collections[nodename]
for item in data:
node = doc.createElement(metadata['item_name'])
node.setAttribute(metadata['item_key'], str(item))
result.appendChild(node)
return result
singular = metadata.get('plurals', {}).get(nodename, None)
if singular is None:
if nodename.endswith('s'):
singular = nodename[:-1]
else:
singular = 'item'
for item in data:
node = self._to_xml_node(doc, metadata, singular, item)
result.appendChild(node)
#TODO(bcwaldon): accomplish this without a type-check
elif isinstance(data, dict):
collections = metadata.get('dict_collections', {})
if nodename in collections:
metadata = collections[nodename]
for k, v in data.items():
node = doc.createElement(metadata['item_name'])
node.setAttribute(metadata['item_key'], str(k))
text = doc.createTextNode(str(v))
node.appendChild(text)
result.appendChild(node)
return result
attrs = metadata.get('attributes', {}).get(nodename, {})
for k, v in data.items():
if k in attrs:
result.setAttribute(k, str(v))
else:
node = self._to_xml_node(doc, metadata, k, v)
result.appendChild(node)
else:
# Type is atom
node = doc.createTextNode(str(data))
result.appendChild(node)
return result
def _create_link_nodes(self, xml_doc, links):
link_nodes = []
for link in links:
link_node = xml_doc.createElement('atom:link')
link_node.setAttribute('rel', link['rel'])
link_node.setAttribute('href', link['href'])
if 'type' in link:
link_node.setAttribute('type', link['type'])
link_nodes.append(link_node)
return link_nodes
class ResponseHeaderSerializer(ActionDispatcher):
"""Default response headers serialization"""
def serialize(self, response, data, action):
self.dispatch(response, data, action=action)
def default(self, response, data):
response.status_int = 200
class ResponseSerializer(object):
"""Encode the necessary pieces into a response object"""
def __init__(self, body_serializers=None, headers_serializer=None):
self.body_serializers = {
'application/xml': XMLDictSerializer(),
'application/json': JSONDictSerializer(),
}
self.body_serializers.update(body_serializers or {})
self.headers_serializer = (headers_serializer or
ResponseHeaderSerializer())
def serialize(self, response_data, content_type, action='default'):
"""Serialize a dict into a string and wrap in a wsgi.Request object.
:param response_data: dict produced by the Controller
:param content_type: expected mimetype of serialized response body
"""
response = webob.Response()
self.serialize_headers(response, response_data, action)
self.serialize_body(response, response_data, content_type, action)
return response
def serialize_headers(self, response, data, action):
self.headers_serializer.serialize(response, data, action)
def serialize_body(self, response, data, content_type, action):
response.headers['Content-Type'] = content_type
if data is not None:
serializer = self.get_body_serializer(content_type)
response.body = serializer.serialize(data, action)
def get_body_serializer(self, content_type):
try:
return self.body_serializers[content_type]
except (KeyError, TypeError):
raise exception.InvalidContentType(content_type=content_type)
class TextDeserializer(ActionDispatcher):
"""Default request body deserialization"""
def deserialize(self, datastring, action='default'):
return self.dispatch(datastring, action=action)
def default(self, datastring):
return {}
class JSONDeserializer(TextDeserializer):
def _from_json(self, datastring):
try:
return jsonutils.loads(datastring)
except ValueError:
msg = _("Cannot understand JSON")
raise exception.MalformedRequestBody(reason=msg)
def default(self, datastring):
return {'body': self._from_json(datastring)}
class XMLDeserializer(TextDeserializer):
def __init__(self, metadata=None):
"""
:param metadata: information needed to deserialize xml into
a dictionary.
"""
super(XMLDeserializer, self).__init__()
self.metadata = metadata or {}
def _from_xml(self, datastring):
plurals = set(self.metadata.get('plurals', {}))
try:
node = minidom.parseString(datastring).childNodes[0]
return {node.nodeName: self._from_xml_node(node, plurals)}
except expat.ExpatError:
msg = _("Cannot understand XML")
raise exception.MalformedRequestBody(reason=msg)
def _from_xml_node(self, node, listnames):
"""Convert a minidom node to a simple Python type.
:param listnames: list of XML node names whose subnodes should
be considered list items.
"""
if len(node.childNodes) == 1 and node.childNodes[0].nodeType == 3:
return node.childNodes[0].nodeValue
elif node.nodeName in listnames:
return [self._from_xml_node(n, listnames) for n in node.childNodes]
else:
result = dict()
for attr in node.attributes.keys():
result[attr] = node.attributes[attr].nodeValue
for child in node.childNodes:
if child.nodeType != node.TEXT_NODE:
result[child.nodeName] = self._from_xml_node(child,
listnames)
return result
def find_first_child_named(self, parent, name):
"""Search a nodes children for the first child with a given name"""
for node in parent.childNodes:
if node.nodeName == name:
return node
return None
def find_children_named(self, parent, name):
"""Return all of a nodes children who have the given name"""
for node in parent.childNodes:
if node.nodeName == name:
yield node
def extract_text(self, node):
"""Get the text field contained by the given node"""
if len(node.childNodes) == 1:
child = node.childNodes[0]
if child.nodeType == child.TEXT_NODE:
return child.nodeValue
return ""
def default(self, datastring):
return {'body': self._from_xml(datastring)}
def __call__(self, datastring):
# Adding a migration path to allow us to remove unncessary classes
return self.default(datastring)
class RequestHeadersDeserializer(ActionDispatcher):
"""Default request headers deserializer"""
def deserialize(self, request, action):
return self.dispatch(request, action=action)
def default(self, request):
return {}
class RequestDeserializer(object):
"""Break up a Request object into more useful pieces."""
def __init__(self, body_deserializers=None, headers_deserializer=None):
self.body_deserializers = {
'application/xml': XMLDeserializer(),
'application/json': JSONDeserializer(),
}
self.body_deserializers.update(body_deserializers or {})
self.headers_deserializer = (headers_deserializer or
RequestHeadersDeserializer())
def deserialize(self, request):
"""Extract necessary pieces of the request.
:param request: Request object
:returns tuple of expected controller action name, dictionary of
keyword arguments to pass to the controller, the expected
content type of the response
"""
action_args = self.get_action_args(request.environ)
action = action_args.pop('action', None)
action_args.update(self.deserialize_headers(request, action))
action_args.update(self.deserialize_body(request, action))
accept = self.get_expected_content_type(request)
return (action, action_args, accept)
def deserialize_headers(self, request, action):
return self.headers_deserializer.deserialize(request, action)
def deserialize_body(self, request, action):
try:
content_type = request.best_match_content_type()
except exception.InvalidContentType:
LOG.debug(_("Unrecognized Content-Type provided in request"))
return {}
if content_type is None:
LOG.debug(_("No Content-Type provided in request"))
return {}
if not len(request.body) > 0:
LOG.debug(_("Empty body provided in request"))
return {}
try:
deserializer = self.get_body_deserializer(content_type)
except exception.InvalidContentType:
LOG.debug(_("Unable to deserialize body as provided Content-Type"))
raise
return deserializer.deserialize(request.body, action)
def get_body_deserializer(self, content_type):
try:
return self.body_deserializers[content_type]
except (KeyError, TypeError):
raise exception.InvalidContentType(content_type=content_type)
def get_expected_content_type(self, request):
return request.best_match_content_type()
def get_action_args(self, request_environment):
"""Parse dictionary created by routes library."""
try:
args = request_environment['wsgiorg.routing_args'][1].copy()
except Exception:
return {}
try:
del args['controller']
except KeyError:
pass
try:
del args['format']
except KeyError:
pass
return args
class Application(object):
"""Base WSGI application wrapper. Subclasses need to implement __call__."""
@classmethod
def factory(cls, global_config, **local_config):
"""Used for paste app factories in paste.deploy config files.
Any local configuration (that is, values under the [app:APPNAME]
section of the paste config) will be passed into the `__init__` method
as kwargs.
A hypothetical configuration would look like:
[app:wadl]
latest_version = 1.3
paste.app_factory = nova.api.fancy_api:Wadl.factory
which would result in a call to the `Wadl` class as
import quantum.api.fancy_api
fancy_api.Wadl(latest_version='1.3')
You could of course re-implement the `factory` method in subclasses,
but using the kwarg passing it shouldn't be necessary.
"""
return cls(**local_config)
def __call__(self, environ, start_response):
r"""Subclasses will probably want to implement __call__ like this:
@webob.dec.wsgify(RequestClass=Request)
def __call__(self, req):
# Any of the following objects work as responses:
# Option 1: simple string
res = 'message\n'
# Option 2: a nicely formatted HTTP exception page
res = exc.HTTPForbidden(detail='Nice try')
# Option 3: a webob Response object (in case you need to play with
# headers, or you want to be treated like an iterable, or or or)
res = Response();
res.app_iter = open('somefile')
# Option 4: any wsgi app to be run next
res = self.application
# Option 5: you can get a Response object for a wsgi app, too, to
# play with headers etc
res = req.get_response(self.application)
# You can then just return your response...
return res
# ... or set req.response and return None.
req.response = res
See the end of http://pythonpaste.org/webob/modules/dec.html
for more info.
"""
raise NotImplementedError(_('You must implement __call__'))
class Debug(Middleware):
"""
Helper class that can be inserted into any WSGI application chain
to get information about the request and response.
"""
@webob.dec.wsgify
def __call__(self, req):
print ("*" * 40) + " REQUEST ENVIRON"
for key, value in req.environ.items():
print key, "=", value
print
resp = req.get_response(self.application)
print ("*" * 40) + " RESPONSE HEADERS"
for (key, value) in resp.headers.iteritems():
print key, "=", value
print
resp.app_iter = self.print_generator(resp.app_iter)
return resp
@staticmethod
def print_generator(app_iter):
"""
Iterator that prints the contents of a wrapper string iterator
when iterated.
"""
print ("*" * 40) + " BODY"
for part in app_iter:
sys.stdout.write(part)
sys.stdout.flush()
yield part
print
class Router(object):
"""
WSGI middleware that maps incoming requests to WSGI apps.
"""
@classmethod
def factory(cls, global_config, **local_config):
"""
Returns an instance of the WSGI Router class
"""
return cls()
def __init__(self, mapper):
"""
Create a router for the given routes.Mapper.
Each route in `mapper` must specify a 'controller', which is a
WSGI app to call. You'll probably want to specify an 'action' as
well and have your controller be a wsgi.Controller, who will route
the request to the action method.
Examples:
mapper = routes.Mapper()
sc = ServerController()
# Explicit mapping of one route to a controller+action
mapper.connect(None, "/svrlist", controller=sc, action="list")
# Actions are all implicitly defined
mapper.resource("network", "networks", controller=nc)
# Pointing to an arbitrary WSGI app. You can specify the
# {path_info:.*} parameter so the target app can be handed just that
# section of the URL.
mapper.connect(None, "/v1.0/{path_info:.*}", controller=BlogApp())
"""
self.map = mapper
self._router = routes.middleware.RoutesMiddleware(self._dispatch,
self.map)
@webob.dec.wsgify
def __call__(self, req):
"""
Route the incoming request to a controller based on self.map.
If no match, return a 404.
"""
return self._router
@staticmethod
@webob.dec.wsgify
def _dispatch(req):
"""
Called by self._router after matching the incoming request to a route
and putting the information into req.environ. Either returns 404
or the routed WSGI app's response.
"""
match = req.environ['wsgiorg.routing_args'][1]
if not match:
return webob.exc.HTTPNotFound()
app = match['controller']
return app
class Resource(Application):
"""WSGI app that handles (de)serialization and controller dispatch.
WSGI app that reads routing information supplied by RoutesMiddleware
and calls the requested action method upon its controller. All
controller action methods must accept a 'req' argument, which is the
incoming wsgi.Request. If the operation is a PUT or POST, the controller
method must also accept a 'body' argument (the deserialized request body).
They may raise a webob.exc exception or return a dict, which will be
serialized by requested content type.
"""
def __init__(self, controller, fault_body_function,
deserializer=None, serializer=None):
"""
:param controller: object that implement methods created by routes lib
:param deserializer: object that can serialize the output of a
controller into a webob response
:param serializer: object that can deserialize a webob request
into necessary pieces
:param fault_body_function: a function that will build the response
body for HTTP errors raised by operations
on this resource object
"""
self.controller = controller
self.deserializer = deserializer or RequestDeserializer()
self.serializer = serializer or ResponseSerializer()
self._fault_body_function = fault_body_function
# use serializer's xmlns for populating Fault generator xmlns
xml_serializer = self.serializer.body_serializers['application/xml']
if hasattr(xml_serializer, 'xmlns'):
self._xmlns = xml_serializer.xmlns
@webob.dec.wsgify(RequestClass=Request)
def __call__(self, request):
"""WSGI method that controls (de)serialization and method dispatch."""
LOG.info(_("%(method)s %(url)s"), {"method": request.method,
"url": request.url})
try:
action, args, accept = self.deserializer.deserialize(request)
except exception.InvalidContentType:
msg = _("Unsupported Content-Type")
LOG.exception(_("InvalidContentType: %s"), msg)
return Fault(webob.exc.HTTPBadRequest(explanation=msg),
self._xmlns)
except exception.MalformedRequestBody:
msg = _("Malformed request body")
LOG.exception(_("MalformedRequestBody: %s"), msg)
return Fault(webob.exc.HTTPBadRequest(explanation=msg),
self._xmlns)
try:
action_result = self.dispatch(request, action, args)
except webob.exc.HTTPException as ex:
LOG.info(_("HTTP exception thrown: %s"), unicode(ex))
action_result = Fault(ex,
self._xmlns,
self._fault_body_function)
except Exception:
LOG.exception(_("Internal error"))
# Do not include the traceback to avoid returning it to clients.
action_result = Fault(webob.exc.HTTPServerError(),
self._xmlns,
self._fault_body_function)
if isinstance(action_result, dict) or action_result is None:
response = self.serializer.serialize(action_result,
accept,
action=action)
else:
response = action_result
try:
msg_dict = dict(url=request.url, status=response.status_int)
msg = _("%(url)s returned with HTTP %(status)d") % msg_dict
except AttributeError, e:
msg_dict = dict(url=request.url, exception=e)
msg = _("%(url)s returned a fault: %(exception)s") % msg_dict
LOG.info(msg)
return response
def dispatch(self, request, action, action_args):
"""Find action-spefic method on controller and call it."""
controller_method = getattr(self.controller, action)
try:
#NOTE(salvatore-orlando): the controller method must have
# an argument whose name is 'request'
return controller_method(request=request, **action_args)
except TypeError as exc:
LOG.exception(exc)
return Fault(webob.exc.HTTPBadRequest(),
self._xmlns)
def _default_body_function(wrapped_exc):
code = wrapped_exc.status_int
fault_data = {
'Error': {
'code': code,
'message': wrapped_exc.explanation}}
# 'code' is an attribute on the fault tag itself
metadata = {'attributes': {'Error': 'code'}}
return fault_data, metadata
class Fault(webob.exc.HTTPException):
""" Generates an HTTP response from a webob HTTP exception"""
def __init__(self, exception, xmlns=None, body_function=None):
"""Creates a Fault for the given webob.exc.exception."""
self.wrapped_exc = exception
self.status_int = self.wrapped_exc.status_int
self._xmlns = xmlns
self._body_function = body_function or _default_body_function
@webob.dec.wsgify(RequestClass=Request)
def __call__(self, req):
"""Generate a WSGI response based on the exception passed to ctor."""
# Replace the body with fault details.
fault_data, metadata = self._body_function(self.wrapped_exc)
xml_serializer = XMLDictSerializer(metadata, self._xmlns)
content_type = req.best_match_content_type()
serializer = {
'application/xml': xml_serializer,
'application/json': JSONDictSerializer(),
}[content_type]
self.wrapped_exc.body = serializer.serialize(fault_data)
self.wrapped_exc.content_type = content_type
return self.wrapped_exc
# NOTE(salvatore-orlando): this class will go once the
# extension API framework is updated
class Controller(object):
"""WSGI app that dispatched to methods.
WSGI app that reads routing information supplied by RoutesMiddleware
and calls the requested action method upon itself. All action methods
must, in addition to their normal parameters, accept a 'req' argument
which is the incoming wsgi.Request. They raise a webob.exc exception,
or return a dict which will be serialized by requested content type.
"""
@webob.dec.wsgify(RequestClass=Request)
def __call__(self, req):
"""
Call the method specified in req.environ by RoutesMiddleware.
"""
arg_dict = req.environ['wsgiorg.routing_args'][1]
action = arg_dict['action']
method = getattr(self, action)
del arg_dict['controller']
del arg_dict['action']
if 'format' in arg_dict:
del arg_dict['format']
arg_dict['request'] = req
result = method(**arg_dict)
if isinstance(result, dict) or result is None:
if result is None:
status = 204
content_type = ''
body = None
else:
status = 200
content_type = req.best_match_content_type()
default_xmlns = self.get_default_xmlns(req)
body = self._serialize(result, content_type, default_xmlns)
response = webob.Response(status=status,
content_type=content_type,
body=body)
msg_dict = dict(url=req.url, status=response.status_int)
msg = _("%(url)s returned with HTTP %(status)d") % msg_dict
LOG.debug(msg)
return response
else:
return result
def _serialize(self, data, content_type, default_xmlns):
"""Serialize the given dict to the provided content_type.
Uses self._serialization_metadata if it exists, which is a dict mapping
MIME types to information needed to serialize to that type.
"""
_metadata = getattr(type(self), '_serialization_metadata', {})
serializer = Serializer(_metadata, default_xmlns)
try:
return serializer.serialize(data, content_type)
except exception.InvalidContentType:
raise webob.exc.HTTPNotAcceptable()
def _deserialize(self, data, content_type):
"""Deserialize the request body to the specefied content type.
Uses self._serialization_metadata if it exists, which is a dict mapping
MIME types to information needed to serialize to that type.
"""
_metadata = getattr(type(self), '_serialization_metadata', {})
serializer = Serializer(_metadata)
return serializer.deserialize(data, content_type)
def get_default_xmlns(self, req):
"""Provide the XML namespace to use if none is otherwise specified."""
return None
# NOTE(salvatore-orlando): this class will go once the
# extension API framework is updated
class Serializer(object):
"""Serializes and deserializes dictionaries to certain MIME types."""
def __init__(self, metadata=None, default_xmlns=None):
"""Create a serializer based on the given WSGI environment.
'metadata' is an optional dict mapping MIME types to information
needed to serialize a dictionary to that type.
"""
self.metadata = metadata or {}
self.default_xmlns = default_xmlns
def _get_serialize_handler(self, content_type):
handlers = {
'application/json': self._to_json,
'application/xml': self._to_xml,
}
try:
return handlers[content_type]
except Exception:
raise exception.InvalidContentType(content_type=content_type)
def serialize(self, data, content_type):
"""Serialize a dictionary into the specified content type."""
return self._get_serialize_handler(content_type)(data)
def deserialize(self, datastring, content_type):
"""Deserialize a string to a dictionary.
The string must be in the format of a supported MIME type.
"""
try:
return self.get_deserialize_handler(content_type)(datastring)
except Exception:
raise webob.exc.HTTPBadRequest(_("Could not deserialize data"))
def get_deserialize_handler(self, content_type):
handlers = {
'application/json': self._from_json,
'application/xml': self._from_xml,
}
try:
return handlers[content_type]
except Exception:
raise exception.InvalidContentType(content_type=content_type)
def _from_json(self, datastring):
return jsonutils.loads(datastring)
def _from_xml(self, datastring):
xmldata = self.metadata.get('application/xml', {})
plurals = set(xmldata.get('plurals', {}))
node = minidom.parseString(datastring).childNodes[0]
return {node.nodeName: self._from_xml_node(node, plurals)}
def _from_xml_node(self, node, listnames):
"""Convert a minidom node to a simple Python type.
listnames is a collection of names of XML nodes whose subnodes should
be considered list items.
"""
if len(node.childNodes) == 1 and node.childNodes[0].nodeType == 3:
return node.childNodes[0].nodeValue
elif node.nodeName in listnames:
return [self._from_xml_node(n, listnames)
for n in node.childNodes if n.nodeType != node.TEXT_NODE]
else:
result = dict()
for attr in node.attributes.keys():
result[attr] = node.attributes[attr].nodeValue
for child in node.childNodes:
if child.nodeType != node.TEXT_NODE:
result[child.nodeName] = self._from_xml_node(child,
listnames)
return result
def _to_json(self, data):
return jsonutils.dumps(data)
def _to_xml(self, data):
metadata = self.metadata.get('application/xml', {})
# We expect data to contain a single key which is the XML root.
root_key = data.keys()[0]
doc = minidom.Document()
node = self._to_xml_node(doc, metadata, root_key, data[root_key])
xmlns = node.getAttribute('xmlns')
if not xmlns and self.default_xmlns:
node.setAttribute('xmlns', self.default_xmlns)
return node.toprettyxml(indent='', newl='')
def _to_xml_node(self, doc, metadata, nodename, data):
"""Recursive method to convert data members to XML nodes."""
result = doc.createElement(nodename)
# Set the xml namespace if one is specified
# TODO(justinsb): We could also use prefixes on the keys
xmlns = metadata.get('xmlns', None)
if xmlns:
result.setAttribute('xmlns', xmlns)
if isinstance(data, list):
collections = metadata.get('list_collections', {})
if nodename in collections:
metadata = collections[nodename]
for item in data:
node = doc.createElement(metadata['item_name'])
node.setAttribute(metadata['item_key'], str(item))
result.appendChild(node)
return result
singular = metadata.get('plurals', {}).get(nodename, None)
if singular is None:
if nodename.endswith('s'):
singular = nodename[:-1]
else:
singular = 'item'
for item in data:
node = self._to_xml_node(doc, metadata, singular, item)
result.appendChild(node)
elif isinstance(data, dict):
collections = metadata.get('dict_collections', {})
if nodename in collections:
metadata = collections[nodename]
for k, v in data.items():
node = doc.createElement(metadata['item_name'])
node.setAttribute(metadata['item_key'], str(k))
text = doc.createTextNode(str(v))
node.appendChild(text)
result.appendChild(node)
return result
attrs = metadata.get('attributes', {}).get(nodename, {})
for k, v in data.items():
if k in attrs:
result.setAttribute(k, str(v))
else:
node = self._to_xml_node(doc, metadata, k, v)
result.appendChild(node)
else:
# Type is atom.
node = doc.createTextNode(str(data))
result.appendChild(node)
return result