2010/9/10 Jesper <jesper.eskil...@gmail.com>

>
> On Sep 10, 7:10 pm, Jason Hsueh <jas...@google.com> wrote:
> > Can you provide a small reproduction of the problem? A couple common
> errors:
> > - custom options need to be specified as "option (<option_name>) =
> <value>;"
> > (parentheses around the identifier)
> > - if you're using the option in a different package than the one in which
> > its defined, it needs to be qualified with the package name
>
> Yes, I'm pretty sure I followed the instructions in the documentation.
>
> > Also, note that protocol buffers were originally designed to get away
> from
> > having to deal with version numbers (see "A bit of history":
> http://code.google.com/apis/protocolbuffers/docs/overview.html) Typically,
> > you would define your protocol in such a way that different versions are
> > still compatible. When that's not practical/possible, people may just
> switch
> > to entirely new messages.
>
> We have a Java-program A which spawns a C++-program B, and A needs to
> know that B can deal with the messages it sends, and if new
> functionality in the protocol is added, A needs to be able to figure
> out if B is sufficiently new to handle the new functionality. So this
> is strictly not so much a protocol version, but rather a program
> version.
>
> I solved this by having one version number encoded in the C++-program
> and another in the Java-program, and a version-message is exchanged
> when they hook up. If B does not present a new enough version number,
> the program is terminated. The only drawback is that I have to change
> the version number in two places when adding functionality to the
> protocol.
>
>
Can you use and enum in the .proto file, with an enum value that you change
(that's kind-of like a constant defined in the .proto file).  Then do the
version number exchange like you do now, but have both the java and c++ code
get the version number from the enum "constant".


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