[lobster_johnson]

True, but gRPC inherits these problems as it's based on Protobuf.

As for free-form data, it should be representable as map[string]interface{}. Our specific use case is a document store that stores documents on behalf of clients. The format of documents cannot be not known by the store, but the API to the store is gRPC. Also, we have a desire for documents to contain higher-level types such as dates, but we're forced to use google.protobuf.Value for this, and treat dates as strings, since Value cannot contain Proto types.

(Our next step is probably to model this explicitly, by defining our own Value message that uses "oneof" to represent all the possible types we need to support, and then using a map of these. But it would be nicer if Protobuf had first-class support.)