sdk-go/samples/nats/message-interoperability/main.go

79 lines
2.0 KiB
Go

/*
Copyright 2021 The CloudEvents Authors
SPDX-License-Identifier: Apache-2.0
*/
package main
import (
"context"
"io"
"log"
"os"
"github.com/kelseyhightower/envconfig"
cloudeventsnats "github.com/cloudevents/sdk-go/protocol/nats/v2"
cloudeventshttp "github.com/cloudevents/sdk-go/v2/protocol/http"
)
type envConfig struct {
// Port on which to listen for cloudevents
Port int `envconfig:"PORT" default:"8080"`
// NATSServer URL to connect to the nats server.
NATSServer string `envconfig:"NATS_SERVER" default:"http://localhost:4222" required:"true"`
// Subject is the nats subject to publish cloudevents on.
Subject string `envconfig:"SUBJECT" default:"sample" required:"true"`
}
func main() {
var env envConfig
if err := envconfig.Process("", &env); err != nil {
log.Printf("[ERROR] Failed to process env var: %s", err)
os.Exit(1)
}
ctx := context.Background()
natsProtocol, err := cloudeventsnats.NewSender(env.NATSServer, env.Subject, cloudeventsnats.NatsOptions())
if err != nil {
log.Fatalf("failed to create nats protcol, %s", err.Error())
}
defer natsProtocol.Close(ctx)
httpProtocol, err := cloudeventshttp.New(cloudeventshttp.WithPort(env.Port))
if err != nil {
log.Fatalf("failed to create http protocol: %s", err.Error())
}
// Pipe all messages incoming to the httpProtocol to the natsProtocol
go func() {
for {
// Blocking call to wait for new messages from httpProtocol
message, err := httpProtocol.Receive(ctx)
if err != nil {
if err == io.EOF {
return // Context closed and/or receiver closed
}
log.Printf("Error while receiving a message: %s", err.Error())
}
// Send message directly to natsProtocol
err = natsProtocol.Send(ctx, message)
if err != nil {
log.Printf("Error while forwarding the message: %s", err.Error())
}
}
}()
// Start the HTTP Server invoking OpenInbound()
go func() {
if err := httpProtocol.OpenInbound(ctx); err != nil {
log.Printf("failed to StartHTTPReceiver, %v", err)
}
}()
<-ctx.Done()
}