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https://issues.apache.org/jira/browse/ZOOKEEPER-1381?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13398994#comment-13398994
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Patrick Hunt commented on ZOOKEEPER-1381:
-----------------------------------------
@nkeywal Having a separate jira sounds reasonable to me. Keep in mind that this
method itself (getting the server version) will have the same problem. ;-)
(say it's introduced in 3.5, then you'll see the same issue when running a 3.5+
client against an older server).
Also keep in mind that we don't provide this getServerVersion method for a
reason - primarily because writing runtime code such as you are suggesting is
more likely to have issues than if you code your client against an explicit
version of the server. (and upgrade with these issues in mind).
Furthermore you might be running in a mixed ensemble - where some servers
support particular features and some don't. Just because the follower you are
connected to is a particular version doesn't mean the leader (or other
followers) are the same version. That will complicate things.
I'd advise you not to go this route.
> Add a method to get the zookeeper server version from the client
> ----------------------------------------------------------------
>
> Key: ZOOKEEPER-1381
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1381
> Project: ZooKeeper
> Issue Type: Improvement
> Components: c client, documentation, java client, server
> Affects Versions: 3.4.2
> Environment: all
> Reporter: nkeywal
> Priority: Minor
> Labels: newbie
>
> Zookeeper client API is designed to be server version agnostic as much as
> possible, so we can have new clients with old servers (or the opposite). But
> there is today no simple way for a client to know what's the server version.
> This would be very useful in order to;
> - check the compatibility (ex: 'multi' implementation available since 3.4
> while 3.4 clients API supports 3.3 servers as well)
> - have different implementation depending on the server functionalities
> A workaround (proposed by Mahadev Konar) is do "echo stat | nc hostname
> clientport" and parse the output to get the version. The output is, for
> example:
> -----------------------
> Zookeeper version: 3.4.2--1, built on 01/30/2012 17:43 GMT
> Clients:
> /127.0.0.1:54951[0](queued=0,recved=1,sent=0)
> Latency min/avg/max: 0/0/0
> Received: 1
> Sent: 0
> Outstanding: 0
> Zxid: 0x500000001
> Mode: follower
> Node count: 7
> --------------------
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