Item item; // ... populate the item's data proto::Item pb_item = item.GetProto(); // retrieve the protocol buffer messageIn this example, the Item object's data is populated, and then the GetProto() method is used to retrieve the protocol buffer message. This message can then be serialized or deserialized, as needed. The package library that contains the GetProto() method is likely to be a protocol buffer library, such as Google's protobuf library or a third-party implementation of the same.