More docs, some API permutation

channels/backends/redis_py.py

@@ -99,5 +99,7 @@ def group_channels(self, group):
             -1,
         )
 
+    # TODO: send_group efficient implementation using Lua
+
     def __str__(self):
         return "%s(host=%s, port=%s)" % (self.__class__.__name__, self.host, self.port)

channels/channel.py

@@ -1,8 +1,6 @@
 import random
 import string
 
-from django.utils import six
-
 from channels import channel_backends, DEFAULT_CHANNEL_BACKEND
 
 
@@ -53,22 +51,6 @@ def as_view(self):
         from channels.adapters import view_producer
         return view_producer(self.name)
 
-    @classmethod
-    def consumer(self, *channels, alias=DEFAULT_CHANNEL_BACKEND):
-        """
-        Decorator that registers a function as a consumer.
-        """
-        # Upconvert if you just pass in a string
-        if isinstance(channels, six.string_types):
-            channels = [channels]
-        # Get the channel 
-        channel_backend = channel_backends[alias]
-        # Return a function that'll register whatever it wraps
-        def inner(func):
-            channel_backend.registry.add_consumer(func, channels)
-            return func
-        return inner
-
 
 class Group(object):
     """

channels/decorators.py

@@ -0,0 +1,24 @@
+import functools
+
+from django.utils import six
+
+from channels import channel_backends, DEFAULT_CHANNEL_BACKEND
+
+
+def consumer(self, *channels, alias=DEFAULT_CHANNEL_BACKEND):
+    """
+    Decorator that registers a function as a consumer.
+    """
+    # Upconvert if you just pass in a string
+    if isinstance(channels, six.string_types):
+        channels = [channels]
+    # Get the channel 
+    channel_backend = channel_backends[alias]
+    # Return a function that'll register whatever it wraps
+    def inner(func):
+        channel_backend.registry.add_consumer(func, channels)
+        return func
+    return inner
+
+
+# TODO: Sessions, auth

channels/interfaces/websocket_twisted.py

@@ -114,6 +114,7 @@ def backend_reader(self):
         """
         while True:
             channels = self.factory.send_channels()
+            # TODO: Send keepalives
             # Quit if reactor is stopping
             if not reactor.running:
                 return

docs/backend-requirements.rst → docs/backends.rst

@@ -1,5 +1,24 @@
-Channel Backend Requirements
-============================
+Backends
+========
+
+Multiple choices of backend are available, to fill different tradeoffs of
+complexity, throughput and scalability. You can also write your own backend if
+you wish; the API is very simple and documented below.
+
+In-memory
+---------
+
+Database
+--------
+
+Redis
+-----
+
+Writing Custom Backends
+-----------------------
+
+Backend Requirements
+^^^^^^^^^^^^^^^^^^^^
 
 While the channel backends are pluggable, there's a minimum standard they
 must meet in terms of the way they perform.
@@ -23,12 +42,14 @@ In particular, a channel backend MUST:
 
 * Preserve the ordering of messages inside a channel
 
-* Never deliver a message more than once
+* Never deliver a message more than once (design for at-most-once delivery)
 
 * Never block on sending of a message (dropping the message/erroring is preferable to blocking)
 
 * Be able to store messages of at least 5MB in size
 
+* Allow for channel and group names of up to 200 printable ASCII characters
+
 * Expire messages only after the expiry period provided is up (a backend may
   keep them longer if it wishes, but should expire them at some reasonable
   point to ensure users do not come to rely on permanent messages)
@@ -41,6 +62,10 @@ In addition, it SHOULD:
 * Provide a ``send_group()`` method which sends a message to every channel
   in a group.
 
+* Make ``send_group()`` perform better than ``O(n)``, where ``n`` is the
+  number of members in the group; preferably send the messages to all
+  members in a single call to your backing datastore or protocol.
+
 * Try and preserve a rough global ordering, so that one busy channel does not
   drown out an old message in another channel if a worker is listening on both.