This document demonstrates how to handle error type responses during RPC calls. You can view the complete example source code here.
Source file path: dubbo-go-sample/error/proto/greet.proto
syntax = "proto3";
package greet;
option go_package = "github.com/apache/dubbo-go-samples/error/proto;greet";
message GreetRequest {
string name = 1;
}
message GreetResponse {
string greeting = 1;
}
service GreetService {
rpc Greet(GreetRequest) returns (GreetResponse) {}
}
Note that in this program design, the Greet method will only consider the request valid if it receives name="right name"; otherwise, it will return an error.
Source file path: dubbo-go-sample/context/go-server/main.go
package main
import (
"context"
"fmt"
"github.com/pkg/errors"
_ "dubbo.apache.org/dubbo-go/v3/imports"
"dubbo.apache.org/dubbo-go/v3/protocol"
"dubbo.apache.org/dubbo-go/v3/server"
greet "github.com/apache/dubbo-go-samples/helloworld/proto"
"github.com/dubbogo/gost/log/logger"
)
type GreetTripleServer struct {
}
func (srv *GreetTripleServer) Greet(ctx context.Context, req *greet.GreetRequest) (*greet.GreetResponse, error) {
name := req.Name
if name != "right name" {
errInfo := fmt.Sprintf("name is not right: %s", name)
logger.Error(errInfo)
return nil, errors.New(errInfo)
}
resp := &greet.GreetResponse{Greeting: req.Name}
return resp, nil
}
func main() {
srv, err := server.NewServer(
server.WithServerProtocol(
protocol.WithPort(20000),
protocol.WithTriple(),
),
)
if err != nil {
panic(err)
}
if err = greet.RegisterGreetServiceHandler(srv, &GreetTripleServer{}); err != nil {
panic(err)
}
if err = srv.Serve(); err != nil {
logger.Error(err)
}
}
From the RPC method signature, we can see that func (srv *GreetTripleServer) Greet(ctx context.Context, req *greet.GreetRequest) (*greet.GreetResponse, error) includes an error return value.
The client makes two calls, one with a valid request and one with an invalid request.
Source file path: dubbo-go-sample/context/go-client/main.go
package main
import (
"context"
"dubbo.apache.org/dubbo-go/v3/client"
_ "dubbo.apache.org/dubbo-go/v3/imports"
greet "github.com/apache/dubbo-go-samples/helloworld/proto"
"github.com/dubbogo/gost/log/logger"
)
func main() {
cli, err := client.NewClient(
client.WithClientURL("127.0.0.1:20000"),
)
if err != nil {
panic(err)
}
svc, err := greet.NewGreetService(cli)
if err != nil {
panic(err)
}
resp, err := svc.Greet(context.Background(), &greet.GreetRequest{Name: "right name"})
if err != nil {
logger.Error(err)
}
logger.Infof("call Greet success: %s", resp.Greeting)
resp, err = svc.Greet(context.Background(), &greet.GreetRequest{Name: "wrong name"})
if err != nil {
logger.Errorf("call Greet failed, err: %s", err.Error())
}
}
Start the server first, then the client. You can observe that the client’s first call succeeds, while the second call fails, and the server returns an error.
2024-02-28 17:49:40 INFO logger/logging.go:42 call Greet success: [right name]
2024-02-28 17:49:40 ERROR logger/logging.go:52 call Greet failed, err: [Failed to invoke the method Greet in the service greet.GreetService. Tried 2 times of the providers [tri://:@127.0.0.1:20000/?interface=greet.GreetService&group=&version= tri://:@127.0.0.1:20000/?interface=greet.GreetService&group=&version= tri://:@127.0.0.1:20000/?interface=greet.GreetService&group=&version=] (3/1)from the registry tri://127.0.0.1:20000/greet.GreetService?app.version=&application=dubbo.io&async=false&bean.name=greet.GreetService&cluster=failover&config.tracing=&environment=&generic=&group=&interface=greet.GreetService&loadbalance=&metadata-type=local&module=sample&name=dubbo.io&organization=dubbo-go&owner=dubbo-go&peer=true&provided-by=&reference.filter=cshutdown®istry.role=0&release=dubbo-golang-3.2.0&remote.timestamp=&retries=&serialization=protobuf&side=consumer&sticky=false×tamp=1709113780&version= on the consumer 30.221.146.234 using the dubbo version 3.2.0. Last error is unknown: name is not right: wrong name.: unknown: name is not right: wrong name]