generate js proto3 canonical json

[amarkowitz]

• this is to enhance the integration of javascript in the protobuf eco-system via enabling the option to use proto3 compatible JSON as the wire format for message passing instead of only supporting binary. This is support is enabled via the new toJSONObject() method on messages
• canonical JSON format definition: https://developers.google.com/protocol-buffers/docs/proto3#json
• relates to Need to better document that toObject() is *not* proto3 JSON protocolbuffers/protobuf-javascript#95

This approach takes direction from the existing binary serialization generation within the js compiler. I am not too familiar with the protobuf ecosystem so it's possible that there are other approaches that are more inline with the trajectory of that project, such as generating Descriptors for the proto definitions and moving all of the serialization logic to the runtime (for example, a JsonFormatter that can read the field definitions from the Descriptors). 🤷‍♂

Also of note, javascript only supports accurate integers up to 2^53-1, so 64 bit is troublesome. See long.js or other implementations for being able to deal with large numbers.

[amarkowitz]

Looks like someone may be trying to support JSON as a wireformat and also provide some other things given this recent checkin from a couple of weeks ago: https://github.com/protocolbuffers/protobuf/tree/master/js/experimental

[kppk]

This is cool!

[kppk]

I like this better :-)

[amarkowitz]

😃 - me too... It's like they've been in the code base and know the eco system. or something ;)

[kppk]

But I was talking about your code :-P

[amarkowitz]

Oh.. Haha! Thanks! I def think that a better approach would be to generate the descriptors for runtime and then use that information to generate JSON. A lot more flexibility there. I'll keep this branch around for posterity and to pick things from tho ;)