Whether you use implicit or explicit persistence, an object database or a relational one, each object in your system will have one or more of the following levels of access permission:
When you persist an object, you put it somewhere other than in memory — to a byte stream (serialization), to a file or to a database. Streaming the object allows you to send it between processes on your computer, across a network, through a modem or over the Internet. Writing it to a file or a database allows you to store it for retrieval at a later time.