Can you pre-process the .proto file(s) into a FileDescriptorSet first?
protoc can do this, using the --descriptor_set_out flag, like:
protoc --descriptor_set_out=my_descriptor_set my_file.proto
another_file.proto ...
my_descriptor_set will then be an encoded set of FileDescriptorProtos, which
you can use to build FileDescriptors, which you can then use to build
DynamicMessages.
If you were using C++ you could use libprotoc directly, but there is no
Java-native parser for .proto files. I suppose you could run protoc as a
background process, though.
On Mon, Mar 23, 2009 at 3:01 PM, kimchy <kim...@gmail.com> wrote:
>
> What I meant is that I have the .proto file, but not the generated
> types it has (I am using Java on the server side). What I am looking
> for is something like this:
>
> Map<String, Descriptor> descriptorsByMessageName = new HashMap<>();
>
> for (protoFile : all proto files) {
> InputStream is = // open input stream against .proto located on FS/
> ClassLoader
> FileDescriptor fd = // how do I do this? basically, parse it from
> is
> for (Desc desc : fd.getMessageDesc()) {
> descriptorsByMessageName(desc.getName(), desc);
> }
> }
>
> Then, once I have the map constructed, I can create DynamicMessage
> based on message Names lookup keys to get the appropriate Descriptor,
> and an InputStream that holds the actual message content. This will
> allow me to write code on the server side that works without actually
> needing the Java types generated from the proto files, but instead use
> the DynamicMessage to get values out of a protobuf stream.
>
> Cheers,
> Shay
>
>
> On Mar 23, 11:47 pm, Kenton Varda <ken...@google.com> wrote:
> > I'm a little confused by your message. You say you have the .proto
> files,
> > but you don't know the types? But don't the .proto files define the
> types?
> > Did you mean to say that you only have actual data encoded as these
> types,
> > and you don't have the type definitions (the .proto files) at all? In
> that
> > case, no, you can't construct a DynamicMessage from them -- the best you
> can
> > do is decode them as an UnknownFieldSet, which doesn't give you much
> > information.
> > If you want your data to be self-describing, you could send along a
> > FileDescriptorSet (defined in google/protobuf/descriptor.proto)
> containing
> > the type definitions. From that you can construct descriptors and thus
> > DynamicMessages.
> >
> >
> >
> > On Mon, Mar 23, 2009 at 2:34 PM, kimchy <kim...@gmail.com> wrote:
> >
> > > Hi,
> >
> > > I am trying to use protocol buffer on the server side without
> > > knowing the types it needs to use, just based on the .proto files, is
> > > that possible? Basically, what I was hoping for is some way to be able
> > > to read proto files into a Descriptor, and then use DynamicMessage to
> > > get values from it. Is that even possible?
> >
> > > Cheers,
> > > Shay
> >
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Protocol Buffers" group.
To post to this group, send email to protobuf@googlegroups.com
To unsubscribe from this group, send email to
protobuf+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/protobuf?hl=en
-~----------~----~----~----~------~----~------~--~---
