update

zackliu · zackliu · commit c243877f39fe · 2022-02-22T13:37:14.000+08:00
diff --git a/articles/azure-web-pubsub/howto-develop-reliable-clients.md b/articles/azure-web-pubsub/howto-develop-reliable-clients.md
@@ -126,6 +126,6 @@ A sample sequence ack:
 }
 ```
 
-The sequence-id is a uint64 incremental number with-in a connection-id session. Subscribers should record the largest sequence-id it ever received and accept all messages with larger sequence-id and drop all messages with smaller or equal sequence-id. The sequence ack supports selective ack, which means if you ack `sequence-id=5`, the service will treat all messages with sequence-id smaller than 5 have already been received by subscribers. Subscribers should ack with the largest sequence-id it recorded, so that the service can skip redelivering messages that subscribers have already received.
+The sequence-id is a uint64 incremental number with-in a connection-id session. Subscribers should record the largest sequence-id it ever received and accept all messages with larger sequence-id and drop all messages with smaller or equal sequence-id. The sequence ack supports cumulative ack, which means if you ack `sequence-id=5`, the service will treat all messages with sequence-id smaller than 5 have already been received by subscribers. Subscribers should ack with the largest sequence-id it recorded, so that the service can skip redelivering messages that subscribers have already received.
 
 All messages are delivered to subscribers in order until the WebSockets connection drops. With sequence-id, the service can have the knowledge about how many messages subscribers have actually received across WebSockets connections with-in a connection-id session. After a WebSockets connection drop, the service will redeliver messages it should deliver but not ack-ed by the subscriber. The service hold messages that are not ack-ed with limit, if messages exceed the limit, the service will close the WebSockets connection and remove the connection-id session. Thus, subscribers should ack the sequence-id as soon as possible.

Original file line number	Diff line number	Diff line change
`@@ -126,6 +126,6 @@ A sample sequence ack:`
`126`	`126`	`}`
`127`	`127`	```
`128`	`128`
`129`		-The sequence-id is a uint64 incremental number with-in a connection-id session. Subscribers should record the largest sequence-id it ever received and accept all messages with larger sequence-id and drop all messages with smaller or equal sequence-id. The sequence ack supports selective ack, which means if you ack `sequence-id=5`, the service will treat all messages with sequence-id smaller than 5 have already been received by subscribers. Subscribers should ack with the largest sequence-id it recorded, so that the service can skip redelivering messages that subscribers have already received.
	`129`	+The sequence-id is a uint64 incremental number with-in a connection-id session. Subscribers should record the largest sequence-id it ever received and accept all messages with larger sequence-id and drop all messages with smaller or equal sequence-id. The sequence ack supports cumulative ack, which means if you ack `sequence-id=5`, the service will treat all messages with sequence-id smaller than 5 have already been received by subscribers. Subscribers should ack with the largest sequence-id it recorded, so that the service can skip redelivering messages that subscribers have already received.
`130`	`130`
`131`	`131`	All messages are delivered to subscribers in order until the WebSockets connection drops. With sequence-id, the service can have the knowledge about how many messages subscribers have actually received across WebSockets connections with-in a connection-id session. After a WebSockets connection drop, the service will redeliver messages it should deliver but not ack-ed by the subscriber. The service hold messages that are not ack-ed with limit, if messages exceed the limit, the service will close the WebSockets connection and remove the connection-id session. Thus, subscribers should ack the sequence-id as soon as possible.