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RE: naming contexts
At 11:35 PM 2001-12-05, Steven Legg wrote:
>> It seems to me that the definition of a "naming context"
>> in LDAP/X.500 makes little sense in the face of multi-master
>> replication. A LDAP/X.500 naming context is subtree of
>> entries held in a single master DSA.
>> Consider three DSAs A, B, C where
>> A masters subtree X
>> B masters subtree Y
>> C masters subtrees X and Y, and
>> Subtrees X and Y are adjacent.
>>From what follows, I assume that Y is subordinate to X.
>> If A and B are masters and C is a shadow of each,
>> LDAP/X.500 says that
>> A holds context X, B holds context Y, and
>> C holds contexts X and Y.
>C holds a shadow copy of contexts X and Y.
Yes, but the distinction here is what values go into
the root DSE namingContexts attribute of each server.
A publishes the name of the vertex of X.
B publishes the name of the vertex of Y.
C publishes the names of the vertex of X and Y.
>> If C masters X and Y and A and B are shadows,
>> LDAP/X.500 says that:
>> A, B, C holds context X
>C holds context X, which is now the union of the subtrees X and Y,
>i.e. there is no longer a context Y. A holds a shadow copy of a
>portion (subtree X) of context X. B holds a shadow copy of a different
>portion (subtree Y) of context X.
A,B,C publishes the name of the vertex of X.
>> If A, B, and C master the subtrees they hold, which
>> contexts does LDUP say they hold?
>Having an entry mastered by more that one master DSA doesn't invalidate
>the definition of naming context as far as I can see, but we do need
>to be a bit more careful how we phrase things.
>A holds a naming context with the context prefix being the root of the
>subtree X. B holds a naming context with the context prefix being the
>root of the subtree Y. C holds a naming context with the context prefix
>being the root of subtree X, the same root as A but with a superset of the
You imply that context prefix information is not replicated
between masters and the definition of a context is local to
There are three basic ways one could define naming contexts
in face of multi-master replication.
a) contexts are determined at each master
b) contexts are determined across all masters
c) contexts are determined at one master
I note that in single-master replication, naming contexts are
defined consistent with all three. In multi-master, you need
to choose one. You appear to choose a), yes?
>For LDUP we're okay if we say we are replicating "replication contexts"
>rather than "naming contexts".
Yes, one could consider the X and Y subtrees as "replication contexts".
>C can be said to hold two adjacent replication contexts (for subtree X and subtree Y).
Yes. One could rephrase the question in terms of replication
contexts, not subtrees.
I think you are saying that where a server masters multiple
adjacent replication contexts, these replication contexts
comprise one naming context on that server. Yes?