Every UNO object, that wants to be serializable, should implement
this interface. The object stores stores itself, when the
write method is called.
The object needs to be created before it deserializes
itself again (by using the read method). Therefor it must be
createable by name via a factory, which is in general
the global service manager. The create and read mechanism
is implemented by the ObjectInputStream.
The serialization format (the series of strings, integers, objects) must
be specified at the specification of the concrete service.
The interface does not support any special versioning mechanism.
reads all the persistent data of the object from the stream.
In case
other XPersistObjects are read from the stream, the implementation uses a factory
to create these objects (in general the global service manager).
The implementation must read the data in the order documented at
the service specification.
