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Go

/*
* Copyright 2025 CloudWeGo Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package main
import (
"context"
"errors"
"io"
"strings"
"github.com/cloudwego/eino/compose"
"github.com/cloudwego/eino/schema"
"github.com/cloudwego/eino-examples/internal/logs"
)
// This example demonstrates an async lambda node inside an Eino graph.
// Scenario 1: Background report generation (invokable).
// Scenario 2: Live transcription stream (streamable) with conversion.
func main() {
ctx := context.Background()
g := compose.NewGraph[string, string]()
// async_invokable: starts a long-running job and waits on a channel.
inv := compose.InvokableLambda(func(ctx context.Context, in string) (string, error) {
notify := make(chan reportResult, 1)
logs.Infof("async_invokable: start report job with input=%q", in)
go generateReport(ctx, in, notify)
logs.Infof("async_invokable: waiting on reportResult notification")
select {
case r := <-notify:
return r.url, r.err
case <-ctx.Done():
return "", ctx.Err()
}
})
// async_streamable: consumes a live stream and converts tokens.
str := compose.StreamableLambda(func(ctx context.Context, in string) (*schema.StreamReader[string], error) {
logs.Infof("async_streamable: start transcription stream with input=%q", in)
upstream := transcribeLive(ctx, in)
converted := schema.StreamReaderWithConvert(upstream, func(tok string) (string, error) {
if tok == "" {
return tok, errors.New("empty token")
}
return strings.ToUpper(tok), nil
})
logs.Infof("async_streamable: waiting on upstream tokens via StreamReaderWithConvert")
return converted, nil
})
_ = g.AddLambdaNode("async_invokable", inv)
_ = g.AddLambdaNode("async_streamable", str)
_ = g.AddEdge(compose.START, "async_invokable")
_ = g.AddEdge("async_invokable", "async_streamable")
_ = g.AddEdge("async_streamable", compose.END)
run, err := g.Compile(ctx)
if err != nil {
logs.Errorf("compile error: %v", err)
return
}
// Invoke: "generate report" path
out, err := run.Invoke(ctx, "Quarterly Sales Report")
if err != nil {
logs.Errorf("invoke error: %v", err)
} else {
logs.Infof("report url: %s", out)
}
// Stream: "transcription" path
stream, err := run.Stream(ctx, "hello world from async node")
if err != nil {
logs.Errorf("stream error: %v", err)
return
}
for {
chunk, err := stream.Recv()
if err != nil {
if errors.Is(err, io.EOF) {
break
}
logs.Tokenf("recv error: %v", err)
break
}
logs.Tokenf("%s", chunk)
}
stream.Close()
}