server.js

var grpc = require('grpc');

var booksProto = grpc.load('books.proto');

// In-memory array of book objects
var books = [{
    id: 123,
    title: 'A Tale of Two Cities',
    author: 'Charles Dickens'
}];

var server = new grpc.Server();
server.addProtoService(booksProto.books.BookService.service, {
    list: function(call, callback) {
        callback(null, books);
    },
    insert: function(call, callback) {
        books.push(call.request);
        callback(null, {});
    }
});

server.bind('127.0.0.1:50051', grpc.ServerCredentials.createInsecure());
server.start();