restgen

restgen is a plugin for protocol buffer compiler. It generates go code for REST endpoints, based on Google's Protocol Buffers (a.k.a. protobuf).

Installation

This tool is written in go. You need a working go installation to install it. Execute the following command in a terminal:

go install github.com/doozer-de/restgen/protoc-gen-bff

This installs the protobuf compiler plugin protoc-gen-bff (where "bff" is an abbreviation for "backend for frontend"). It must be in your $PATH for the protocol compiler to find it.

Usage

1. Define a service in your protobuf. Every service will be defined with a service map and rpc methods.

A service map definition looks like the following:

	option (pbmap.service_map) = {
		version: "1"
		base_uri: "/base_uri/"
		target_package: "samplesvc"
	};

This service map is defined in pbmap/map.proto:

• version:
• base_uri: defines the base URI, e. g. http://[address]/[base_uri]/[path]...
• target_package: defines the name of the package, where the generated file will be placed. This option doesn't affect the location of the file - this has to be defined with OUT_DIR in the protoc command operand --bff_out=OUT_DIR

A rpc method would be defined like the following:

	rpc Methodname(RequestMethod) returns (ResponseMethod) {
		option (pbmap.method_map) = {
            method: "method"
            path: "/[path]/:id"
            query_string: "key=[message].[field]:[data_type]"
            body: "*"
        };
    }

The method map is defined in pbmap/map.proto.

Explanation:

• method: defines the used HTTP method, supported are: Get, Put, Post, Delete
• path: identifies the method, has to be unique in this service and has to be compatible with Julian Schmidt's HTTP Router; Format a/b/:c/:d where a/b/ are fixed and :c and :d are parameters mapped to C and D in the underlying GRPC Request
• query_string: Format "key1=:var1&key=:var2": they keys will be mapped to the variables var1, var2 of the unterlying GRPC Request
• body: indicates, if the request has a body or not

2. The messages are defined as usual

3. Compile the protobuf.

4. Execute the following command in a terminal:

protoc [OPTION] --bff_out=OUT_DIR PROTO_FILES

Features

Supported

• atomic datatypes
• maps
• user defined messages; inside of the same package and outside of this package)
• HTTP Methods: Get, Put, Post, Delete
• path parameter; also with deep paths
• query strings; also with deep paths

Not supported

• enums in path parameter and query strings

Example

You can find a sample protobuf definition in samplesvc/pb/samplesvc.proto and the generated code in samplesvc/samplesvc_gen.go.