Multiple Services

TwirpQL’s architecture expects that for each service declaration in a Protobuf file, you get a full GraphQL layer under one sub-package.

In other words, TwirpQL expects only one service for every code generation cycle. If your .proto file has only one service in it, then TwirpQL automatically chooses it for creating the GraphQL layer.

However, if the .proto has multiple service declarations, then you must explicitly pick which service you want to generate a GraphQL layer for.

For example, say you have the following service.proto file:

syntax = "proto3";
package hello;
option go_package = "hello";

service One {

service Two {

Then you must specify which service you want to create a GraphQL for in the following way:

protoc --twirpql_out=service=Two:. service.proto

What happens if I want a GraphQL layer for multiple services?

It’s quite common that one server = one service. However, it’s not uncommon that one server has multiple services.

Therefore, you can generate multiple GraphQL layers in the same project. Here’s how:

Say you have 3 .proto files, each with 1 service: svc1.proto, svc2.proto, svc3.proto

Then you can create the following command for each of them:

protoc --twirpql_out=dest=svc1:. svc1.proto
protoc --twirpql_out=dest=svc2:. svc2.proto
protoc --twirpql_out=dest=svc3:. svc3.proto

This way, each generation cycle will create a different sub-package. By default, TwirpQL creates a sub-package called twirpql but in this case, we overrode this default and create different names for each sub-package.

Once all sub-packages are created, then we can import them individually and place them under different URL paths:

package main

import (

    svc1 "./svc1"
    svc2 "./svc2"
    svc3 "./svc3"

func main() {
    http.Handle("/svc1", svc1.Handler(...))
    http.Handle("/svc2", svc2.Handler(...))
    http.Handle("/svc3", svc3.Handler(...))