Module serde 

Available on crate features grpc and http and serde and std only.

A Codec which (de)serializes messages using serde.

Where ProstCodec is limited to protobuf messages generated from a .proto file, SerdeCodec works with any Rust type which implements Serialize and DeserializeOwned, serialized in the wire format of your choice.

Together with the define_service! macro this gives you gRPC services defined and served fully in Rust, without protobuf or a build script.

What you give up is reach: a .proto file is a contract other languages can generate code from, and nothing here replaces that.

What you get is that your own types are the contract. There is no generated message type to convert to and from, an enum whose variants carry data needs no oneof, and there is no protoc or build step between you and a change to a service.

Formats

JSON is provided out of the box, as JsonFormat behind the json feature. Any other format is a matter of implementing SerdeFormat for it: a serialize and a deserialize call, plus a type MyCodec<T, U> = SerdeCodec<MyFormat, T, U> alias to name the result. The JSON implementation is the reference for the shape of it, MessagePack via rmp-serde is the same two calls.

JSON being the one that ships does not make it the one to use. It is here because you can read it on the wire, which helps when debugging and in examples. It is also the slowest and most verbose option.

MessagePack gives you a binary encoding from the same types and derives: smaller and faster. Rust-native formats such as postcard or bincode are smaller and faster still, but only Rust can read them. The codec is a type parameter, so pick one per service.

All of them can stay backwards compatible, through optional fields, defaults and ignored unknown fields. Unlike protobuf, nothing enforces that for you.

Note that SerdeCodec is generic over the message types as well as the format, so naming it in a service definition means naming all three: SerdeCodec<JsonFormat, _, _>, where the _ are the message types to infer. An alias such as JsonCodec avoids that.

Interoperability

gRPC has no content type negotiation: both ends of a route have to be generated with the same codec, see Codec for the details.

Structs

JsonFormat

The JSON SerdeFormat, as implemented by serde_json.

SerdeCodec

A Codec which encodes T and decodes U using serde and the format F (: SerdeFormat).

SerdeDecoder

A Decoder which knows how to deserialize U using the format F.

SerdeEncoder

An Encoder which knows how to serialize T using the format F.

Traits

SerdeFormat

The wire format used by a SerdeCodec.

Type Aliases

JsonCodec

A SerdeCodec which encodes T and decodes U as JSON.