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From Michael Han <h...@apache.org>
Subject Re: [Question] How watches work?
Date Thu, 29 Aug 2019 23:42:21 GMT
>> why we also trigger watches on server side.

Because server side needs generate the watched events and deliver the
events to client side, so client side can trigger watcher.

>> Any advice on how watches work, both client side and server side?

At high level think it as a push based change notification mechanism, where
the notification itself is lightweight event. Client side watcher reacts to
events and server side watcher reacts to watched objects and generate these
events. Watchers are kept on client / server side and not transmitted over
the wire as they are heavy; only lightweight events are transmitted.

I think there are also lots of online resources that go into details of how
watchers work, if you search (hint - use chinese).

On Wed, Aug 28, 2019 at 8:24 PM Zili Chen <wander4096@gmail.com> wrote:

> Hi zookeepers,
>
> Notice that we both hold watches manager in client side and server side,
> it really confuses me why we also trigger watches on server side.
>
> In my understanding, watchers registered on client and when client
> process WatchEvent, it triggers those watchers.
>
> Any advice on how watches work, both client side and server side?
>
> Best,
> tison.
>

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