Endpoint Coprocessor Protocol and implementation versioning

[Asaf Mesika <as...@gmail.com>]

Hi,

I'm writing an Endpoint Coprocessor for HBase v0.94.6 (cdh4.3.1).

I'm trying to understand how the CoprocessorProtocol and
CoprocessorEndPoint implementation versioning works, both backwards and
forward.

For instance, I have my protocol as:

public interface MyQueryProtocol extends CoprocessorProtocol{

    public static final long VERSION = 1L;

    public MyResult query(int x) throws IOException;
}

Let's say I have deployed them both at the client and at the Region Server
(and their respective implementation.
Now lets say after 0.5 year I've discovered I want to change the method by
adding another parameter y:

public interface MyQueryProtocol extends CoprocessorProtocol{

    public static final long VERSION = *2L*;

    public MyResult query(int x*, int y*) throws IOException;
}

Am I suppose to have both the old method and the new method in the
interface?
What happens if I update the client first - is it even possible, or is it
always the order of: server first and then client?

So in essence: How am I supposed to do both in the protocol and endpoint
implementation in terms of versioning.

Thanks!

Re: Endpoint Coprocessor Protocol and implementation versioning

[Ted Yu <yu...@gmail.com>]

When cluster does rolling restart to upgrade servers, you would want to
keep clients working during that period of time.
This means version 2 of the endpoint should implement both methods.

Once cluster is fully upgraded, you can switch the clients over to using
the version 2 protocol.

Cheers


On Thu, Oct 17, 2013 at 12:18 PM, Asaf Mesika <as...@gmail.com> wrote:

> Hi,
>
> I'm writing an Endpoint Coprocessor for HBase v0.94.6 (cdh4.3.1).
>
> I'm trying to understand how the CoprocessorProtocol and
> CoprocessorEndPoint implementation versioning works, both backwards and
> forward.
>
> For instance, I have my protocol as:
>
> public interface MyQueryProtocol extends CoprocessorProtocol{
>
>     public static final long VERSION = 1L;
>
>     public MyResult query(int x) throws IOException;
> }
>
> Let's say I have deployed them both at the client and at the Region Server
> (and their respective implementation.
> Now lets say after 0.5 year I've discovered I want to change the method by
> adding another parameter y:
>
> public interface MyQueryProtocol extends CoprocessorProtocol{
>
>     public static final long VERSION = *2L*;
>
>     public MyResult query(int x*, int y*) throws IOException;
> }
>
> Am I suppose to have both the old method and the new method in the
> interface?
> What happens if I update the client first - is it even possible, or is it
> always the order of: server first and then client?
>
> So in essence: How am I supposed to do both in the protocol and endpoint
> implementation in terms of versioning.
>
> Thanks!
>