package main

import (
	"context"
	"fmt"
	"os"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/keepalive"
	"github.com/vardius/pushpull/proto"
)

func main() {
    host:= "0.0.0.0"
    port:= 9090
    ctx := context.Background()

	opts := []grpc.DialOption{
		grpc.WithInsecure(),
		grpc.WithKeepaliveParams(keepalive.ClientParameters{
			Time:                10 * time.Second, // send pings every 10 seconds if there is no activity
			Timeout:             20 * time.Second, // wait 20 second for ping ack before considering the connection dead
			PermitWithoutStream: true,             // send pings even without active streams
		}),
    }

	conn, err := grpc.DialContext(ctx, fmt.Sprintf("%s:%d", host, port), opts...)
	if err != nil {
		os.Exit(1)
    }
    defer conn.Close()

	client := proto.NewPushPullClient(conn)

    client.Push(ctx, &proto.PushRequest{
		Topic:   "my-topic",
		Payload: []byte("Hello you!"),
    })
}

Pull

package main

import (
	"context"
	"fmt"
	"os"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/keepalive"
	"github.com/vardius/pushpull/proto"
)

func main() {
    host:= "0.0.0.0"
    port:= 9090
    ctx := context.Background()

	opts := []grpc.DialOption{
		grpc.WithInsecure(),
		grpc.WithKeepaliveParams(keepalive.ClientParameters{
			Time:                10 * time.Second, // send pings every 10 seconds if there is no activity
			Timeout:             20 * time.Second, // wait 20 second for ping ack before considering the connection dead
			PermitWithoutStream: true,             // send pings even without active streams
		}),
    }

	conn, err := grpc.DialContext(ctx, fmt.Sprintf("%s:%d", host, port), opts...)
	if err != nil {
		os.Exit(1)
    }
    defer conn.Close()

	client := proto.NewPushPullClient(conn)

	stream, err := client.Pull(ctx, &proto.PullRequest{
		Topic: "my-topic",
	})
	if err != nil {
		os.Exit(1)
	}

	for {
		resp, err := stream.Recv()
		if err != nil {
		    os.Exit(1) // stream closed or error
		}

		fmt.Println(resp.GetPayload())
	}
}

Protocol Buffers

Generating client and server code

To generate the gRPC client and server interfaces from pushpull.proto service definition. Use the protocol buffer compiler protoc with a special gRPC Go plugin. For more info read

From this directory run:

$ make build

Running this command generates the following files in this directory:

pushpull.pb.go

This contains:

All the protocol buffer code to populate, serialize, and retrieve our request and response message types An interface type (or stub) for clients to call with the methods defined in the services. An interface type for servers to implement, also with the methods defined in the services.