trooba-grpc-transport

trooba-grpc-transport

gRPC transport for trooba pipeline.

The module provides a client and service side gRPC transport implementation for trooba pipeline.

Get Involved

• Contributing: Pull requests are welcome!
  • Read CONTRIBUTING.md and check out our bite-sized and help-wanted issues
  • Submit github issues for any feature enhancements, bugs or documentation problems
• Support: Join our gitter chat to ask questions to get support from the maintainers and other Trooba developers
  • Questions/comments can also be posted as github issues

Install

npm install trooba-grpc-transport --save

Usage

Service invocation

var port = 50001;
var grpcTransport = require('trooba-grpc-transport');

require('trooba')
    .use(grpcTransport, {
        protocol: 'http:',
        hostname: 'localhost',
        port: port,
        proto: require.resolve('path/to/hello.proto'),
        connectTimeout: 100,
        socketTimeout: 1000
    })
    .build('client:default')
    .hello('Bob', function (err, response) {
        console.log(err, response)
    });

Sample proto definition:

syntax = "proto3";

// The hello service definition.
service Hello {
    // Sends a greeting
    rpc SayHello ( HelloRequest) returns (  HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
    string name = 1;
}

// The response message containing the greetings
message HelloReply {
    string message = 1;
}

Trooba based service

var pipeServer = Trooba.use(transport, {
    port: port,
    hostname: 'localhost',
    proto: Grpc.load(require.resolve('./path/to/hello.proto'))
})
.use(function handler(pipe) {
    pipe.on('request', (request, next) => {
        // do something with request
        console.log('gRPC request metadata:', request.headers);
        next();
    });
    pipe.on('request:data', (data, next) => {
        // do something with request stream data chunk
        console.log('request chunk:', data);
        next();
    });
    pipe.on('request:end', (data, next) => {
        // do something with stream end
        console.log('end of request stream');
        next();
    });

    pipe.on('response', (response, next) => {
        // do something with response
        console.log('gRPC response metadata:', response.headers);
        next();
    });
    pipe.on('response:data', (data, next) => {
        // do something with response stream data chunk
        console.log('response chunk:', data);
        next();
    });
    pipe.on('response:end', (data, next) => {
        // do something with end of response stream
        console.log('end of response stream');
        next();
    });
})
.use(function controller(pipe) {
    // handle request/response here
    pipe.on('request', request => {
        pipe.respond({
            body: 'Hello ' + request.body.name
        });
    });
});

var app = pipeServer.build('server:default');

svr = app.listen();
console.log('toorba service is listening on port:', port);

Architecture

The module exports service and client API which matches exactly the API provided by gRPC module.

Once request/response/data chunk enters the trooba pipeline, it assumes more generic API and request like data structures.

Trooba framework does not dictate specific data structures that should be used for request/response/messages/stream objects. It assumes basic requirements and leaves everything else to the implementor of the transport.

This transport goes further and defines some specifics for data it operates with:

• Possible flows:
  • request/response is a basic interaction between client and service
  • request/stream is a flow where for a single request it results in response stream
  • stream/response is a flow where for request stream the backend generates a single response
  • stream/stream is a flow where for the request stream the backend generates a response stream
• All the above flows use request and response object to initiate the flow and streaming uses arbitrary data chunks
• Request object structure:
  • body contains request data which is a message object in gRPC terms
  • headers contains request headers that match gRPC metadata
  • path matches gRPC package namespace and service name separated by '/'. For example:

  'foo.bar.v1.Hello.sayHello' => '/foo/bar/v1/Hello/sayHello'
  

• Response object structure:
  • body contains response data which is a message object in gRPC terms
  • headers contains response headers that match gRPC metadata
  • status is gRPC status
• Data chunk matches gRPC streaming data

The client transport uses two timeouts:

• connectTimeout sets the deadline for establishing the connection
• socketTimeout sets the deadline for response or any further response chunk; whenever a new chunk is received the transport resets the socket timeout

Advanced examples

For more advanced examples, please take a look at unit tests You can also find an implementation of simple service router here.

• Router example:

module.exports = function routes() {
    var router = Router.create();
    router.use({
        path: 'com/xyz/helloworld/Hello/sayHello',
        handle: require('./sayHello')
    });
    router.use({
        path: 'Hello/sayHello',
        handle: require('./sayHello')
    });
    router.use({
        path: 'Hello/sayHelloAll',
        handle: require('./sayHelloAll')
    });
    router.use({
        path: 'Hello/beGreeted',
        handle: require('./beGreeted')
    });

    return router.build();
};

• Service:

var pipeServer = Trooba
.use(transport, {
    port: 40000,
    hostname: 'localhost',
    proto: Server.proto
})
.use(routes());

// create an app
var app = pipeServer.build().create('server:default');

// start it
app.listen(() => {
    console.log('The server is ready');
});