Scaling Issues for Certificate Systems
Some issues of scaling are intrinsic to certificate systems, i.e., can be
understood largely in terms of system functionality, however it is implemented.
We also mention some issues that quickly arise when one considers how
one might implement them.
Intrinsic
Cost of recertifying
-
At some point, executing code is the
cost of knowledge. One must decide when
knowledge is worth establishing.
-
Granularity can be made fine to
appropriately minimize the dependency
of certificates on texts.
-
Allow rechecking of certificates
incrementally (as a collection)
with the possibility of leaving
a certificate intact -- which
does not propagate rechecking.
Cost of Cloning objects
-
Cloning does not cause reconsideration;
only deleting or changing content does.
-
The clone of a text can often be represented
much smaller than the cloned text comprising
a pointer to the original and a table used
as a map to change identifiers in the text.
-
Although one may choose to clone some objects
along with all objects that refer to them,
one can stipulate any subset of objects for
cloning, so one can exploit judgments of
what is relevant for the purpose.
Extrinsic
-
Certificates dominate numerically, but are typically small
(consisting of many pointers to more substantial texts)
and many can be expected to be shortlived.
-
Clients must be able to abort updates.
-
Clients must get advice about probable consequences
of changes to decide whether to continue.
-
Backpointers must be maintained
-
tracing back to
pertinent certificates for rechecking must be fast
-
selecting submaps requires building backpointer subsets for each
object in the submap