Non-intrusive object serialization

[Sabyasachi Basu]

Most C++ object serialization techniques are intrusive, that is they
require all serializable classes need to have functions to stream in
and stream out their contents.

I came across "non-intrusive serialization" while going through the
tutorial on Robert Ramey's serialization library for Boost. However,
it is not clear to me how to implement serialization without the
cooperation of the classes being serialized.

Can someone through some light on this concept?

Thanks in advance.
Sabyasachi

 

[Claudio Puviani]

Most C++ object serialization techniques are intrusive, that is they
require all serializable classes need to have functions to stream in
and stream out their contents.

I came across "non-intrusive serialization" while going through the
tutorial on Robert Ramey's serialization library for Boost. However,
it is not clear to me how to implement serialization without the
cooperation of the classes being serialized.

Can someone through some light on this concept?

By "non-intrusive", he means that the coupling of the class to be serialized and
the serialization mechanism is done by a third entity. This third entity is
created with the knowledge of how to extract and reconstitute another object's
data. Ramey's serialization library simplifies the specification of this third
entity.

Design-wise, this external coordinator is the cleanest approach, but it suffers
from redundancy and any changes to the class being persisted must be reflected
in the serialization helper. The only way to avoid this is to have a
preprocessor that generates the helper classes, and if you've ever dealt with
ODMG or even CORBA, you're probably cringing.

Claudio Puviani