Merge pull request #294 from ably/289-fix-ack-pending-inconsistency

Do not fail ACK-pending messages for a failed resume

Author: lawrence-forooghian

textile/features.textile

@@ -509,10 +509,11 @@ h3(#realtime-connection). Connection
 * @(RTN6)@ A @Connection@ is successful and considered @CONNECTED@ once the "websocket":https://ably.com/topic/websockets connection is open and the initial @CONNECTED@ @ProtocolMessage@ has been received
 * @(RTN21)@ If the @CONNECTED@ @ProtocolMessage@ contains a @connectionDetails@ property, the attributes within @ConnectionDetails@ will be used as the defaults for this client library, overriding any configured options at the time the @CONNECTED@ @ProtocolMessage@ is received
 * @(RTN7)@ @ACK@ and @NACK@:
-** @(RTN7a)@ All @ProtocolMessage@ @Presence@ and @Message@ objects sent to Ably expect either an @ACK@ or @NACK@ from Ably to confirm successful receipt and acceptance or failure respectively. For clarity, it is unnecessary to fail the publish operation of a message using a timer. Instead the client library can rely on: the realtime system will send an @ACK@ or @NACK@ when connected; the client library will fail all awaiting messages once @SUSPENDED@ (see "RTN7c":#RTN7c); upon reconnecting, the client will resend all message awaiting a response, and the realtime system in turn will respond with an @ACK@ or @NACK@ (see "RTN19a":#RTN19a)
+** @(RTN7a)@ All @ProtocolMessage@ @Presence@ and @Message@ objects sent to Ably expect either an @ACK@ or @NACK@ from Ably to confirm successful receipt and acceptance or failure respectively. For clarity, it is unnecessary to fail the publish operation of a message using a timer. Instead the client library can rely on: the realtime system will send an @ACK@ or @NACK@ when connected; the client library will fail all awaiting messages once @SUSPENDED@ (see "RTN7e":#RTN7e); upon reconnecting, the client will resend all message awaiting a response, and the realtime system in turn will respond with an @ACK@ or @NACK@ (see "RTN19a":#RTN19a)
 ** @(RTN7b)@ Every @ProtocolMessage@ that expects an @ACK@ or @NACK@ sent must contain a unique serially incrementing @msgSerial@ integer value starting at zero. The @msgSerial@ along with the @count@ for incoming @ACK@ and @NACK@ @ProtocolMessages@ indicates which messages succeeded or failed to be delivered
-** @(RTN7c)@ If a connection enters the @SUSPENDED@, @CLOSED@ or @FAILED@ state, or if the connection state is lost, and an @ACK@ or @NACK@ has not yet been received for a message, the client should consider the delivery of those messages as failed, meaning their callback (or language equivalent) should be called with an error representing the reason for the state change, and they should be removed from any @RTN19a@ retry queue
-** @(RTN7d)@ If the @queueMessages@ client option (@TO3g@) has been set to @false@, then when a connection enters the @DISCONNECTED@ state, any messages which have not yet been @ACK@d should be considered to have failed, with the same effect as in @RTN7c@
+** @(RTN7c)@ This clause has been replaced by "@RTN7e@":#RTN7e (it contained a mistake). It was valid up to and including specification version @TBD@.
+** @(RTN7e)@ If a connection enters the @SUSPENDED@, @CLOSED@ or @FAILED@ state, and an @ACK@ or @NACK@ has not yet been received for a message, the client should consider the delivery of those messages as failed, meaning their callback (or language equivalent) should be called with an error representing the reason for the state change, and they should be removed from any @RTN19a@ retry queue
+** @(RTN7d)@ If the @queueMessages@ client option (@TO3g@) has been set to @false@, then when a connection enters the @DISCONNECTED@ state, any messages which have not yet been @ACK@d should be considered to have failed, with the same effect as in @RTN7e@
 * @(RTN22)@ Ably can request that a connected client re-authenticates by sending the client an @AUTH@ @ProtocolMessage@. The client must then immediately start a new authentication process as described in "RTC8":#RTC8
 ** @(RTN22a)@ Ably reserves the right to forcibly disconnect a client that does not re-authenticate within an acceptable period of time, or at any time the token is deemed no longer valid. A client is forcibly disconnected following a @DISCONNECTED@ message containing an error code in the range @40140 <= code < 40150@. This will in effect force the client to re-authenticate and resume the connection immediately, see "RTN15h":#RTN15h
 * @(RTN8)@ @Connection#id@ attribute:
@@ -610,7 +611,7 @@ h3(#realtime-connection). Connection
 *** @(RTN17f1)@ a @DISCONNECTED@ response with an @error.statusCode@ in the range @500 <= code <= 504@
 ** @(RTN17e)@ If the realtime client is connected to a fallback host endpoint, then for the duration that the transport is connected to that host, all HTTP requests, such as history or token requests, should be first attempted to the same datacenter the realtime connection is established with i.e. the same fallback host must be used as the default HTTP request host. If however the HTTP request against that fallback host fails, then the normal fallback host behavior should be followed attempting the request against another fallback host as described in "RSC15":#RSC15
 * @(RTN19)@ Transport state side effects - when a transport is disconnected for any reason:
-** @(RTN19a)@ Any @ProtocolMessage@ that is awaiting an @ACK@/@NACK@ on the old transport will not receive the @ACK@/@NACK@ on the new transport. The client library must therefore resend any @ProtocolMessage@ that is awaiting a @ACK@/@NACK@ to Ably in order to receive the expected @ACK@/@NACK@ for that message (subject to @RTN7c@/@RTN7d@). The Ably service is responsible for keeping track of messages, ignoring duplicates and responding with suitable @ACK@/@NACK@ messages
+** @(RTN19a)@ Any @ProtocolMessage@ that is awaiting an @ACK@/@NACK@ on the old transport will not receive the @ACK@/@NACK@ on the new transport. The client library must therefore resend any @ProtocolMessage@ that is awaiting a @ACK@/@NACK@ to Ably in order to receive the expected @ACK@/@NACK@ for that message (subject to @RTN7e@/@RTN7d@). The Ably service is responsible for keeping track of messages, ignoring duplicates and responding with suitable @ACK@/@NACK@ messages
 *** @(RTN19a1)@ One possible implementation of this requirement would be to add any in-flight messages to the @RTL6c2@ connection-wide queue of messages that will be sent once the connection next becomes @CONNECTED@
 *** @(RTN19a2)@ In the case of an @RTN15c6@ successful resume, the @msgSerial@ of the reattempted @ProtocolMessage@s should remain the same as for the original attempt. In the case of an @RTN15c7@ failed resume, the message must be assigned a new @msgSerial@ from the SDK's internal counter.
 ** @(RTN19b)@ If there are any pending channels i.e. in the @ATTACHING@ or @DETACHING@ state, the respective @ATTACH@ or @DETACH@ message should be resent to Ably