feat: implement client-side streaming file upload example and document it in GRPC.md

examples/grpcentity/client.go

@@ -37,6 +37,33 @@ func AskUpdateSensingData(ctx context.Context, m protoapi.IoTServiceClient, devi
 	return m.UpdateSensingData(ctx, request)
 }
 
+func AskUploadFile(ctx context.Context, m protoapi.IoTServiceClient, fileName string, fileData []byte) (*protoapi.UploadStatus, error) {
+	stream, err := m.UploadFile(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	chunkSize := 1024 // 1KB 단위 청크
+	totalBytes := len(fileData)
+
+	for i := 0; i < totalBytes; i += chunkSize {
+		end := i + chunkSize
+		if end > totalBytes {
+			end = totalBytes
+		}
+
+		err := stream.Send(&protoapi.FileChunk{
+			FileName: fileName,
+			Content:  fileData[i:end],
+		})
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return stream.CloseAndRecv()
+}
+
 func ClientRun(addr string) {
 	conn, err := grpc.NewClient(addr, grpc.WithTransportCredentials(insecure.NewCredentials()))
 	if err != nil {
@@ -67,4 +94,19 @@ func ClientRun(addr string) {
 	}
 	fmt.Println("Sensing Update Success:", res.Success)
 	fmt.Println("Sensing Update Message:", res.Message)
+
+	// 4단계: 파일 업로드 스트리밍 실행 예제
+	dummyData := make([]byte, 10240) // 10KB 가상 더미 데이터
+	for i := range dummyData {
+		dummyData[i] = byte(rand.Intn(256))
+	}
+	fmt.Println("Uploading dummy file (10KB) via Client Streaming...")
+	status, err := AskUploadFile(context.Background(), client, "firmware.bin", dummyData)
+	if err != nil {
+		fmt.Println("File upload failed:", err)
+		return
+	}
+	fmt.Println("Upload Success:", status.Success)
+	fmt.Println("Upload Message:", status.Message)
+	fmt.Printf("Uploaded Bytes: %d bytes\n", status.BytesUploaded)
 }