[OAI-implementers] List Id's for multiple sets

Simeon Warner simeon@lanl.gov
Thu, 8 Feb 2001 13:43:32 -0700 (MST)

On Thu, 8 Feb 2001, deridder wrote:
> Now that we're adding more sets, I'm suddenly unclear about the usage of
> ListIdentifiers and ListRecords, where the set specification is optional.
> When no set is specified, should I list ids/records from first one set,
> then another, then another, till I run out of sets?  
>  (alphabetical order?)

The only meaning is that you should list the complete contents of
the repository -- regardless of whether items belong to none, one
or more sets.

The order in which you return ids/records is not specified by
the protocol. You may choose any convenient order.
> Using resumption tokens, should I keep track of which sets I've covered so
> far, and pick up where I left off, so that all sets are covered, when no
> set is specified?

This is entirely implementation dependent. The protocol spec. explicitly
says that the resumptionToken is opaque. I suggest you do whatever
makes the implementation simplest.
>   This is looking more complicated than I expected.  With no dates
> specified, and no sets specified, the list could be enormous;  and as more
> and more sets are added, the resumption tokens could get pretty hairy too.

We haven't touched on issues of how large the resumptionToken might
get. I think one should try to avoid them getting too huge.
>   Question to those who have implemented this for multiple sets:  is this
> how you have done it, or do you have a better way?

I _choose_ to encode the equivalent parameters for a request to continue
the list. This is possible because I _choose_ to return ids/records in
date order with 1 day granularity. 


>  --Jody