Add Retry Interval to REQUEST_ERROR

draft-ietf-moq-transport.md

@@ -2203,6 +2203,7 @@ REQUEST_ERROR Message {
   Length (16),
   Request ID (i),
   Error Code (i),
+  Retry Interval (i),
   Error Reason (Reason Phrase),
 }
 ~~~
@@ -2212,66 +2213,88 @@ REQUEST_ERROR Message {
 
 * Error Code: Identifies an integer error code for request failure.
 
+* Retry Interval: The minimum time (in seconds) before the request SHOULD be
+  sent again, plus one. If the value is 0, the request SHOULD NOT be retried.
+
 * Error Reason: Provides a text description of the request error. See
  {{reason-phrase}}.
 
 The application SHOULD use a relevant error code in REQUEST_ERROR,
-as defined below. Most codepoints have identical meanings for various request
-types, but some have request-specific meanings.
+as defined below and assigned in {{iana-request-error}}. Most codepoints have
+identical meanings for various request types, but some have request-specific
+meanings.
 
-INTERNAL_ERROR (0x0):
-: An implementation specific or generic error occurred.
+If request is retryable with the same parameters at a later time, the sender of
+REQUEST_ERROR includes a non-zero Retry Interval in the message. If it is
+sending more than one such message within a second or so across one or more
+sessions, it SHOULD apply randomization to each retry interval so that retries
+are spread out over time, minimizing the risk of synchronized retry storms.  The
+Retry Interval value MAY be one if the request can be retried immediately.
 
-UNAUTHORIZED (0x1):
+If the sender has no information as to when a request is likely to be
+successful, it MAY apply randomization around a default interval of 30 seconds.
+
+If a Retry Interval exceeds the lifetime of a necessary authentication token
+used in the request, so that a retry at that time would fail, the sender SHOULD
+use an error code indicating a new authentication token is needed.
+
+INTERNAL_ERROR:
+: An implementation specific or generic error occurred. This might be retryable
+or not, depending on the imlementation conditions that caused the error.
+
+UNAUTHORIZED:
 : The subscriber is not authorized to perform the requested action on the given
-track.
+track.  This might be retryable if the authorization token is not yet valid.
 
-TIMEOUT (0x2):
+TIMEOUT:
 : The subscription could not be completed before an implementation specific
   timeout. For example, a relay could not establish an upstream subscription
   within the timeout.
 
-NOT_SUPPORTED (0x3):
+NOT_SUPPORTED:
 : The endpoint does not support the type of request.
 
-MALFORMED_AUTH_TOKEN (0x4):
+MALFORMED_AUTH_TOKEN:
 : Invalid Auth Token serialization during registration (see
   {{authorization-token}}).
 
-EXPIRED_AUTH_TOKEN (0x5):
+EXPIRED_AUTH_TOKEN:
 : Authorization token has expired ({{authorization-token}}).
 
 Below are errors for use by the publisher. They can appear in response to
 SUBSCRIBE, FETCH, TRACK_STATUS, and SUBSCRIBE_NAMESPACE, unless otherwise noted.
 
-DOES_NOT_EXIST (0x10):
-: The track or namespace is not available at the publisher.
+DOES_NOT_EXIST:
+: The track or namespace is not available at the publisher. This might be
+retryable or not, if the target might exist later.
 
-INVALID_RANGE (0x11):
+INVALID_RANGE:
 : In response to SUBSCRIBE or FETCH, specified Filter or range of Locations
-cannot be satisfied.
+cannot be satisfied. This might be retryable if the range is expected to have
+objects in the future.
 
-MALFORMED_TRACK (0x12):
-: In response to a FETCH, a relay publisher detected that the track was
+MALFORMED_TRACK:
+: In response to a FETCH, a relay publisher detected the track was
 malformed (see {{malformed-tracks}}).
 
 The following are errors for use by the subscriber. They can appear in response
 to PUBLISH or PUBLISH_NAMESPACE, unless otherwise noted.
 
-UNINTERESTED (0x20):
-: The subscriber is not interested in the track or namespace.
+UNINTERESTED:
+: The subscriber is not interested in the track or namespace. This might be
+retryable if it expects to be interested later.
 
 Errors below can only be used in response to one message type.
 
-PREFIX_OVERLAP (0x30):
+PREFIX_OVERLAP:
 : In response to SUBSCRIBE_NAMESPACE, the namespace prefix overlaps with another
 SUBSCRIBE_NAMESPACE in the same session.
 
-INVALID_JOINING_REQUEST_ID(0x32):
+INVALID_JOINING_REQUEST_ID:
 : In response to a Joining FETCH, the referenced Request ID is not an
 `Established` Subscription.
 
-UNKNOWN_STATUS_IN_RANGE(0x33):
+UNKNOWN_STATUS_IN_RANGE:
 : In response to a FETCH, the requested range contains an object with unknown
 status.
 
@@ -3924,6 +3947,13 @@ TODO: register the URI scheme and the ALPN and grease the Extension types
 | INVALID_JOINING_REQUEST_ID | 0x32 | {{message-request-error}} |
 | UNKNOWN_STATUS_IN_RANGE    | 0x33 | {{message-request-error}} |
 
+The range of error codes including 0x100 to 0xffff is reserved for
+implementation-speceific codes.
+
+The range of error codes starting with 0x10000 is reserved for
+provisional error codes that are under consideration for a permanent
+code point by the IETF.
+
 ### PUBLISH_DONE Codes {#iana-publish-done}
 
 | Name               | Code | Specification            |