Put SUBSCRIBE_NAMESPACE on a stream, make Namespaces and PUBLISH independent

draft-ietf-moq-transport.md

@@ -724,10 +724,14 @@ The first stream opened is a client-initiated bidirectional control stream where
 the endpoints exchange Setup messages ({{message-setup}}), followed by other
 messages defined in {{message}}.
 
-This specification only specifies a single use of bidirectional streams. Objects
-are sent on unidirectional streams.  Because there are no other uses of
-bidirectional streams, a peer MAY close the session as a `PROTOCOL_VIOLATION` if
-it receives a second bidirectional stream.
+This specification only specifies two uses of bidirectional streams, the control
+stream and SUBSCRIBE_NAMESPACE. Objects are sent on unidirectional streams.
+
+A unidirectional stream containing Objects or bidirectional stream(s) containing a
+SUBSCRIBE_NAMESPACE could arrive prior to the control stream, in which case the
+data SHOULD be buffered until the control stream arrives and setup is complete.
+If an implementation does not want to buffer, it MAY reset other bidirectional
+streams before the session and control stream are established.
 
 The control stream MUST NOT be closed at the underlying transport layer during the
 session's lifetime.  Doing so results in the session being closed as a
@@ -1156,26 +1160,28 @@ The syntax of these messages is described in {{message}}.
 
 If the subscriber is aware of a namespace of interest, it can send
 SUBSCRIBE_NAMESPACE to publishers/relays it has established a session with. The
-recipient of this message will send any relevant PUBLISH_NAMESPACE,
-PUBLISH_NAMESPACE_DONE or PUBLISH messages for that namespace, or more specific
-part of that namespace.  This includes echoing back PUBLISH or PUBLISH_NAMESPACE
-messages to the endpoint that sent them.  If an endpoint accepts its own
-PUBLISH, this behaves as self-subscription described in {{subscriptions}}.
-
-A publisher MUST send exactly one REQUEST_OK or
-REQUEST_ERROR in response to a SUBSCRIBE_NAMESPACE. The subscriber
-SHOULD close the session with a protocol error if it detects receiving more than
-one.
+recipient of this message will send any relevant NAMESPACE,
+NAMESPACE_DONE or PUBLISH messages for that namespace, or more specific
+part of that namespace.  This includes echoing back published Tracks and/or Track
+Namespaces under the SUBSCRIBE_NAMESPACE prefix to the endpoint that sent them.
+If an endpoint accepts its own PUBLISH, this behaves as self-subscription described
+in {{subscriptions}}.
+
+The subscriber sends SUBSCRIBE_NAMESPACE on a new bidirectional stream and the
+publisher MUST send a single REQUEST_OK or REQUEST_ERROR as the first message on the
+bidirectional stream in response to a SUBSCRIBE_NAMESPACE. The subscriber
+SHOULD close the session with a protocol error if it detects receiving more
+than one.
 
 The receiver of a REQUEST_OK or REQUEST_ERROR ought to
 forward the result to the application, so the application can decide which other
 publishers to contact, if any.
 
-An UNSUBSCRIBE_NAMESPACE withdraws a previous SUBSCRIBE_NAMESPACE. It does not
-prohibit original publishers from sending further PUBLISH_NAMESPACE or PUBLISH
-messages, but relays MUST NOT send any further PUBLISH messages to a client
-without knowing the client is interested in and authorized to receive the
-content.
+A SUBSCRIBE_NAMESPACE can be cancelled by closing the stream with
+either a FIN or RESET_STREAM. Cancelling does not prohibit original publishers
+from sending further PUBLISH_NAMESPACE or PUBLISH messages, but relays MUST NOT
+send any further PUBLISH messages to a client without knowing the client is
+interested in and authorized to receive the content.
 
 ## Publishing Namespaces
 
@@ -1639,14 +1645,16 @@ The following Message Types are defined:
 |-------|-----------------------------------------------------|
 | 0x6   | PUBLISH_NAMESPACE  ({{message-pub-ns}})             |
 |-------|-----------------------------------------------------|
+| 0x8   | NAMESPACE  ({{message-namespace}})                  |
+|-------|-----------------------------------------------------|
 | 0x9   | PUBLISH_NAMESPACE_DONE  ({{message-pub-ns-done}})   |
 |-------|-----------------------------------------------------|
+| 0xE   | NAMESPACE_DONE  ({{message-namespace-done}})        |
+|-------|-----------------------------------------------------|
 | 0xC   | PUBLISH_NAMESPACE_CANCEL ({{message-pub-ns-cancel}})|
 |-------|-----------------------------------------------------|
 | 0x11  | SUBSCRIBE_NAMESPACE ({{message-subscribe-ns}})      |
 |-------|-----------------------------------------------------|
-| 0x14  | UNSUBSCRIBE_NAMESPACE ({{message-unsub-ns}})        |
-|-------|-----------------------------------------------------|
 
 An endpoint that receives an unknown message type MUST close the session.
 Control messages have a length to make parsing easier, but no control messages
@@ -2967,6 +2975,27 @@ PUBLISH_NAMESPACE Message {
 
 * Parameters: The parameters are defined in {{version-specific-params}}.
 
+## NAMESPACE {#message-namespace}
+
+The NAMESPACE message is similar to the PUBLISH_NAMESPACE message, except
+it is sent on the response stream of a SUBSCRIBE_NAMESPACE request.
+All NAMESPACE messages are in response to a SUBSCRIBE_NAMESPACE, so only
+the namespace tuples after the 'Track Namespace Prefix' are included
+in the 'Track Namespace Suffix'.
+
+~~~
+NAMESPACE Message {
+  Type (i) = 0x8,
+  Length (16),
+  Track Namespace Suffix (..),
+}
+~~~
+{: #moq-transport-ns-format title="MOQT NAMESPACE Message"}
+
+* Track Namespace Suffix: Specifies the final portion of a track's
+  namespace as defined in {{track-name}} after removing namespace tuples included in
+  'Track Namespace Prefix' {message-subscribe-ns}.
+
 ## PUBLISH_NAMESPACE_DONE {#message-pub-ns-done}
 
 The publisher sends the `PUBLISH_NAMESPACE_DONE` control message to indicate its
@@ -2985,6 +3014,27 @@ PUBLISH_NAMESPACE_DONE Message {
 * Request ID: The Request ID of the PUBLISH_NAMESPACE that is being terminated. See
   {{message-subscribe-req}}.
 
+## NAMESPACE_DONE {#message-namespace-done}
+
+The publisher sends the `NAMESPACE_DONE` control message to indicate its
+intent to stop serving new subscriptions for tracks within the provided Track
+Namespace. All NAMESPACE_DONE messages are in response to a SUBSCRIBE_NAMESPACE,
+so only the namespace tuples after the 'Track Namespace Prefix' are included
+in the 'Track Namespace Suffix'.
+
+~~~
+NAMESPACE_DONE Message {
+  Type (i) = 0xE,
+  Length (16),
+  Track Namespace Suffix (..)
+}
+~~~
+{: #moq-transport-ns-done-format title="MOQT NAMESPACE_DONE Message"}
+
+* Track Namespace Suffix: Specifies the final portion of a track's
+  namespace as defined in {{track-name}}. The namespace begins with the
+  'Track Namespace Prefix' specified in {message-subscribe-ns}.
+
 ## PUBLISH_NAMESPACE_CANCEL {#message-pub-ns-cancel}
 
 The subscriber sends an `PUBLISH_NAMESPACE_CANCEL` control message to
@@ -3014,16 +3064,18 @@ PUBLISH_NAMESPACE_CANCEL Message {
 
 ## SUBSCRIBE_NAMESPACE {#message-subscribe-ns}
 
-The subscriber sends the SUBSCRIBE_NAMESPACE control message to a publisher to
-request the current set of matching published namespaces and `Established`
-subscriptions, as well as future updates to the set.
+The subscriber sends a SUBSCRIBE_NAMESPACE control message on a new
+bidirectional stream to a publisher to request the current set of matching
+published namespaces and/or `Established` subscriptions, as well as future
+updates to the set.
 
 ~~~
 SUBSCRIBE_NAMESPACE Message {
   Type (i) = 0x11,
   Length (16),
   Request ID (i),
   Track Namespace Prefix (..),
+  Subscribe Options (i),
   Number of Parameters (i),
   Parameters (..) ...
 }
@@ -3042,15 +3094,20 @@ SUBSCRIBE_NAMESPACE Message {
   Track Namespace Prefix consisting of 0 or greater than than 32 Track Namespace
   Fields, it MUST close the session with a `PROTOCOL_VIOLATION`.
 
+* Subscribe Options: Allows subscribers to request PUBLISH (0x00),
+  NAMESPACE (0x01), or both (0x02) for a given SUBSCRIBE_NAMESPACE request.
 
 * Parameters: The parameters are defined in {{version-specific-params}}.
 
-The publisher will respond with REQUEST_OK or
-REQUEST_ERROR.  If the SUBSCRIBE_NAMESPACE is successful, the publisher will
-immediately forward existing PUBLISH_NAMESPACE and PUBLISH messages that match
-the Track Namespace Prefix that have not already been sent to this subscriber.
-If the set of matching PUBLISH_NAMESPACE messages changes, the publisher sends
-the corresponding PUBLISH_NAMESPACE or PUBLISH_NAMESPACE_DONE message.
+The publisher will respond with REQUEST_OK or REQUEST_ERROR on the response half
+of the stream.  If the SUBSCRIBE_NAMESPACE is successful, the publisher will
+send matching NAMESPACE messages on the response stream if they are requested.
+If it is an error, the stream will be immediately closed via FIN.
+Also, any matching PUBLISH messages without an `Established` Subscription will be
+sent on the control stream. When there are changes to the namespaces or
+subscriptions being published and the subscriber is subscribed to them,
+the publisher sends the corresponding NAMESPACE, NAMESPACE_DONE,
+or PUBLISH messages.
 
 A subscriber cannot make overlapping namespace subscriptions on a single
 session. Within a session, if a publisher receives a SUBSCRIBE_NAMESPACE with a
@@ -3074,27 +3131,6 @@ set the FORWARD parameter to 1, or indicate that value by omitting the parameter
 (see {{subscriptions}}).
 
 
-## UNSUBSCRIBE_NAMESPACE {#message-unsub-ns}
-
-A subscriber issues a `UNSUBSCRIBE_NAMESPACE` message to a publisher indicating
-it is no longer interested in PUBLISH_NAMESPACE, PUBLISH_NAMESPACE_DONE and
-PUBLISH messages for the specified track namespace prefix.
-
-The format of `UNSUBSCRIBE_NAMESPACE` is as follows:
-
-~~~
-UNSUBSCRIBE_NAMESPACE Message {
-  Type (i) = 0x14,
-  Length (16),
-  Request ID (i),
-}
-~~~
-{: #moq-transport-unsub-ann-format title="MOQT UNSUBSCRIBE_NAMESPACE Message"}
-
-* Request ID: The Request ID of the SUBSCRIBE_NAMESPACE
-  ({{message-subscribe-ns}}) being cancelled by this message.
-
-
 # Data Streams and Datagrams {#data-streams}
 
 A publisher sends Objects matching a subscription on Data Streams or Datagrams