[cap-talk] Styles of persistance

[Bill Frantz]

shap at eros-os.com (Jonathan S. Shapiro) on Monday, March 31, 2008 wrote:

>In most cases, the best way to upgrade an object is to serialize its
>state, instantiate the new version, and have the new version read in the
>old state (possibly using an intermediate, transient format converter to
>separate out the conversion logic).
>
>To the extent that this is true, the only objects requiring a complex
>upgrade protocol are objects that require on-line update.

Perhaps an interesting use case is the
KeyKOS/EROS/CapROS/Coyotos(?) space bank. Instances of the space
bank have life-times from minutes to the life of the system.
Serialization is not used to move it from system to system. :-) It
has a significant internal data structure to keep track of
in-use/free, and the objects to be rescinded when a space bank is
zapped. And, as allocation strategies change, it is likely to need
to be changes.

It would be useful to get the upgrade path for the space bank right
in the first release.

Cheers - Bill

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