This repository hosts Prysm's service interface definitions for the Ethereum 2.0 API. These protocol buffer service definitions support gRPC as well as JSON over HTTP.

More indepth descriptions of each service are available in this section of our official documentation. For more general information on the functionality of gRPC and protocol buffers, see the gRPC guide. If you still have questions, feel free to stop by either our Discord or Gitter and a member of the team or our community will be happy to assist you.

Thanks for wanting to contribute to our eth2 API! Go libraries may be generated from the ethereumapis repository using Bazel, making it easy to make changes to the schemas needed and generate Go files from them. Here's what you need to get started:

• A modern, UNIX operating system
• The latest release of Bazel installed
• The cmake package installed
• The git package installed

Say you want to add a new endpoint to the BeaconChain gRPC service in our API schema to retrieve orphaned blocks. First, make sure the functionality you wish to add is not already covered by one of our endpoints on https://api.prylabs.network. Also, keep in mind making strict changes to the API schema can often times be difficult without a significant reason as this API is used by many different developers building on eth2. If you are confident in your desired changes, you can proceed by modifying the protobuf schema:

service BeaconChain {
    // Retrieve orphaned blocks from the eth2 chain.
    rpc GetOrphanedBlocks(OrphanedBlocksRequest) returns (OrphanedBlocksResponse) {
        option (google.api.http) = {
            get: "/eth/v1alpha1/beacon/blocks/orphaned"
        };
    }
    ...
}

message OrphanedBlocksRequest {
    uint64 slot = 1;
}

message OrphanedBlocksResponse {
    repeated BeaconBlock blocks = 1;
}

After making your changes, you can regenerate the Go libraries from the schema by running:

$ ./scripts/update-go-pbs.sh

Then, open a pull request with your changes on https://github.com/prysmaticlabs/ethereumapis. Next, you'll be ready to implement your new changes in Prysm itself.

Ensure you have read our contribution guidelines first. Then, once your changes to the API schema are merged into the master branch of ethereumapis, you can update Prysm's dependency on ethereumapis to its latest version with the command:

$ bazel run //:gazelle -- update-repos github.com/prysmaticlabs/ethereumapis

Prysm also utilizes generated mocks for testing gRPC requests/responses, so you will also need to regenerate the required mocks by running:

$ ./scripts/update-mockgen.sh

Now, you will be able to implement your required changes in Prysm.

All of the gRPC services should define JSON over HTTP endpoints by specifying HTTPRules. Developers may choose to bundle a REST service of gRPC with their client implementation binaries, or alternatively, they may use a JSON encoding proxy such as Envoy Proxy, grpc-gateway, etc.

For more information on gRPC transcoding, see the examples found here.

Code sample:

service Messaging {
    rpc GetMessage(GetMessageRequest) returns (Message) {
        option (google.api.http) = {
            get: "/v1/{name=messages/*}"
        };
    }
}
message GetMessageRequest {
    string name = 1; // Mapped to URL Path.
}
message Message {
    string text = 1; // The resource content.
}

This enables an HTTP REST to gRPC mapping, as shown below:

The majority of field primitive types for Ethereum are either bytes or uint64. The canonical JSON mapping for those fields are a Base64 encoded string for bytes, or a string representation of uint64. Since JavaScript loses precision for values over MAX_SAFE_INTEGER, uint64 must be a JSON string in order to accommodate those values. If the field value not changed and is still set to protobuf's default, this field will be omitted from the JSON encoding entirely.

For more details on JSON mapping for other types, view the relevant section in the proto3 language guide.

• Awesome gRPC
• Google's API Style Guide
• Language reference for protoc3
• Protocol Buffer Basics: Go
• Transcoding gRPC to JSON/HTTP using Envoy

Apache 2.0