(I'm assumig the "optional" isn't there in the real example)
You can't simply change between proto2 and proto3. In proto3 everything is
optional with an implicit zero default. This is fundamentally incompatible
with consumers who have a "required" expectation **unless** you happen to
never send the value zero. Because whenever your value is zero, it will be
omitted and the consumer will complain about a missing required field.
Options:
- update the consumers **first** so that they don't have a "required"
expectation
- never send zero in that field
- don't change to proto3
Marc
On 16 Jun 2017 10:04 p.m., "yihao yang" <yangyihao1...@gmail.com> wrote:
> I updated a proto file from proto2 to proto3 as follows.
>
> Previous proto2:
> message RegisterWatcherResponse {
> required int32 rc = 1;
> optional uint64 sendTime = 2;
> }
>
>
> Now proto3:
> message RegisterWatcherResponse {
> int32 rc = 1;
> optional uint64 sendTime = 2;
> }
>
> I tested compatibility by using old version client with using proto2
> RegisterWatcherResponse and receiving responses from a server using
> proto3 RegisterWatcherResponse.
> It turns out clients got failure message like follows:
> [libprotobuf ERROR google/protobuf/message_lite.cc:118] Can't parse
> message of type "RegisterWatcherResponse" because it is missing required
> fields: rc
> I'm sure the server side responses have rc filed.
> Can anyone help me why I got this error? Is proto3 compatible with proto2
> in this scenario?
> What can I do to make it work?
>
> Thanks,
> Yihao
>
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