Type URLs and Any types

[Josh Humphries]

The protobuf docs for the Any type talk about the URL being a real URL, where an HTTP GET request will reply with encoded google.protobuf.Type message. The doc further states that URLs with no scheme assume HTTPS (and runtime support that I've seen looks like it intentionally leaves out the scheme when generating type URLs).

However, the given URL examples for all well-known types don't work. Any GET request for https://type.googleapis.com/<message> fails with a 404. The actual example in the Any doc is for google.protobuf.Duration, and https://type.googleapis.com/google.protobuf.Duration simply does not work.

I don't necessarily need these to work, but I have written stuff for resolving types per the doc and have no out-of-the-box URLs I can play with to test it.. It seems like an issue that none of the documented examples actually work.

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Josh Humphries
jh...@bluegosling.com

[Feng Xiao]

Can you create an github issue and give more context about how you plan to use it? Right now the type service doesn't exist because we find no use case of it for our API service stack.

 

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Josh Humphries
jh...@bluegosling.com

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[Josh Humphries]

On Thu, Apr 20, 2017 at 2:03 PM, Feng Xiao <xiao...@google.com> wrote:

On Wed, Apr 19, 2017 at 5:25 PM, Josh Humphries <jh...@bluegosling.com> wrote:

The protobuf docs for the Any type talk about the URL being a real URL, where an HTTP GET request will reply with encoded google.protobuf.Type message. The doc further states that URLs with no scheme assume HTTPS (and runtime support that I've seen looks like it intentionally leaves out the scheme when generating type URLs).

However, the given URL examples for all well-known types don't work. Any GET request for https://type.googleapis.com/<message> fails with a 404. The actual example in the Any doc is for google.protobuf.Duration, and https://type.googleapis.com/google.protobuf.Duration simply does not work.

I don't necessarily need these to work, but I have written stuff for resolving types per the doc and have no out-of-the-box URLs I can play with to test it.. It seems like an issue that none of the documented examples actually work.

Can you create an github issue and give more context about how you plan to use it? Right now the type service doesn't exist because we find no use case of it for our API service stack.

I'm actually writing something for dynamic services. It currently uses GRPC service reflection, but I was looking at supporting the google.protobuf.Api type, too (first converting Api, Type, and Enum objects into equivalent descriptors). I was also looking at implementing dynamic type resolution for Any types the same way: download the Type object, generate a message descriptor from it, and then use that to de-serialize the payload.

I don't need to implement this for my project. I just figured I would flesh these things out, for the sake of completeness, since it's part of the spec in the published documentation on https://developers.google.com/protocol-buffers/.

So I'd appreciate the docs being updated to reflect reality. If reality is that there will be no dynamic type resolution strategy and that clients of Any messages must have all message URLs statically registered in order to parse the payloads, that's fine. It just needs to be documented that way.