egg-grpc

grpc plugin for egg

Install

$ npm i egg-grpc --save

// {app_root}/config/plugin.js
exports.grpc = {
  enable: true,
  package: 'egg-grpc',
};

Configuration

// {app_root}/config/config.default.js
exports.grpc = {
  endpoint: 'localhost:50051',
  // dir: 'app/proto', // proto files dir, relative path
  // property: 'grpc', // default attach to `ctx.grpc.**`
  // loadOpts: { convertFieldsToCamelCase: true, }, // message field case: `string user_name` -> `userName`
};

see config/config.default.js for more detail.

Usage

fixtures:

app/proto
├── egg
│   └── test
│       ├── game.proto
│       └── message.proto
├── uc
│   └── test.proto
└── share.proto

// app/proto/share.proto
syntax = "proto3";

package egg.share;

message Status {
  string code = 1;
  string err_msg = 2;
}

service ShowCase {
  rpc Echo(Status) returns (Status) {}
}

quickstart:

// mount by `package` define, not proto file path
const client = ctx.grpc.egg.share.showCase;
const result = yield client.echo({ code: 200 });
console.log(result);

Folder Structure

• default to load proto files from app/proto.
• file path is only use for file manager, it DON’T affect the proto class path at ctx and app.
• such as app/proto/share.proto, it defined as package egg;, so will visit as
  • yield ctx.grpc.egg.share.showCase.echo(data, meta, options)
  • new app.grpcProto.egg.share.Status({ code: 200 })
  • new app.grpcProto.egg.share.ShowCase(address)
  • new ctx.grpcProto.egg.share.ShowCase(address)

Name Conversion

• Protobuff Style Guide
• GRPC Concepts

term	case at proto	case when load
package	lowercase with .	camleCase if contains _
service	PascalCase	camleCase when initialize at ctx
rpc	PascalCase	camleCase
message	PascalCase	PascalCase at app
field	snake_case	camleCase
enums	CONSTANT_CASE	CONSTANT_CASE

API

Custom Options

• {Number} timeout - for convenient usage of deadline, equals to { deadline: Date.now() + timeout }

Service && Message

You can get service instance and invoke rpc by ctx.mypackage.myService.myRpc({ id: 1 }).

Usually, you don’t need to instantiate a message instace, grpc will do it for you, however you can create it by new app.grpcProto.mypackage.SomeMessage({ id: 1 }).

Unary RPC

/**
 * Unary RPC, such as `rpc Echo(Request) returns (Response) {}`
 * @param {Object} data - data sent to sever
 * @param {Object|grpc.Metadata} [metadata] - metadata, support plain object
 * @param {Object} [options] - { timeout }
 * @return {Promise} response promise chain
 * @see http://www.grpc.io/docs/guides/concepts.html#unary-rpc
 */
// const client = ctx.grpc.<package>.<service>;
yield client.echo(data, metadata, options);
yield client.echo(data, options);

Client Streaming RPC

/**
 * Client Streaming RPC, such as `rpc EchoClientStream(stream Request) returns (Response) {}`
 * @param {Object|grpc.Metadata} [metadata] - metadata, support plain object
 * @param {Object} [options] - { timeout }
 * @param {Function} [callback] - callback for response, `(err, response) => {}`
 * @return {Stream} write stream
 * @see http://www.grpc.io/docs/guides/concepts.html#client-streaming-rpc
 */
const stream = client.echoClientStream(meta, options, callback);
// const stream = client.echoClientStream(callback);
// const stream = client.echoClientStream(meta, callback);
// trigger order: metadata -> callback -> status
stream.once('metadata', meta => {});
stream.once('status', status => {});
stream.on('error', status => {});
// send data to server or end
stream.write(data1);
stream.write(data2);
stream.end(data4);

Server Streaming RPC

/**
 * Server Streaming RPC, such as `rpc EchoServerStream(Request) returns (stream Response) {}`
 * @param {Object} data - data sent to sever
 * @param {Object|grpc.Metadata} [metadata] - metadata, support plain object
 * @param {Object} [options] - { timeout }
 * @return {Stream} read stream
 * @see http://www.grpc.io/docs/guides/concepts.html#server-streaming-rpc
 */
const stream = client.echoServerStream(data, meta, options);
// trigger order: metadata -> data -> status -> end
stream.on('data', response => {});
stream.on('end', response => {});
stream.once('metadata', meta => {});
stream.once('status', status => {});
stream.on('error', status => {});

Bidirectional Streaming RPC

/**
 * Bidirectional Streaming RPC, such as `rpc echoStreamStream(stream Request) returns (stream Response) {}`
 * @param {Object|grpc.Metadata} [metadata] - metadata, support plain object
 * @param {Object} [options] - { timeout }
 * @return {Stream} duplex stream
 * @see http://www.grpc.io/docs/guides/concepts.html#bidirectional-streaming-rpc
 */
const stream = client.echoStreamStream(meta, options);
// trigger order: metadata -> data -> status -> end
stream.on('data', response => {});
stream.on('end', () => {});
stream.once('metadata', meta => {});
stream.once('status', status => {});
stream.on('error', status => {});
// send data to server or end
stream.write(data1);
stream.write(data2);
stream.end(data3);

Example

see grpc.tests.js.

Questions & Suggestions

Please open an issue here.

License

MIT