Proposal for Leaf Guidance of Dynamic Queries


                                 Mario Solares

                               Free Peers, Inc.

                                   June 2003

Problem

Dynamic Querying has a limitation concerning client side filters that can
only be addressed by the client. An ultrapeer has no knowledge of client
side filters and therefore might terminate the query early because it
has no knowledge of hits dropped by those filters. It could be argued
that the query should be rich enough in the first place so as to not
generate a query hit that will be dropped, however that is beyond the
scope of this document.

Proposal

We propose that when an ultrapeer is performing dynamic querying on behalf
of a leaf that has requested control, the ultrapeer will request the
number of hits that have satisfied the leaves client side filters. This
Query Status Request, originated by the ultrapeer, will have the original
query message guid. The ultrapeer will need to wait for the leaf to reply
before sending the next query. The Query Status Response, again containing
the original query guid, will indicate the number of hits.

Query Status Responses can be sent unsolicited and the ultrapeer should
handle them gracefully. If the leaf does not reply to a Query Status
Request within 10 seconds the query can be terminated by the ultrapeer.

Modifications

           
We propose using bit 12 of the minspeed field to indicate status awareness.

            Query Message
 __________________________________________________________________________
|   Fields    | Minimum Speed |Search Criteria|  NUL (0x00)   | (Optional) |
|_____________|_______________|____String_____|__Terminator___|_Query_Data_|
|_Byte_offset_|_____0...1_____|_____2...N_____|______N+1______|_N+2...L-1__|

   Minimum Speed: Setting bits 15 and 12 will indicate that the client
   wishes to control the query and will accept Query Status Requests and
   will provide Query Status Responses.

New Vendor Messages
       We propose creating two new vendor messages.

            Query Status Request
 __________________________________________________________________________
|_____Fields______|___Vendor_ID___|__Sub-Selector___|_______Version________|
|___Byte_offset___|_____0...3_____|_______4-5_______|_________6-7__________|

   Vendor ID: "BEAR" - 0x42454152.
   Sub-Selector: 11 - 0x000B
   Version: 1

            Query Status Response
 ____________________________________________________________________________
|              |               |              |              |               |
|Fields        |   Vendor-ID   | Sub-Selector |   Version    |   Hit Count   |
|______________|_______________|______________|______________|_______________|
|_Bytes_Offset_|_____0...3_____|_____4-5______|_____6-7______|______8-9______|

   Vendor ID: "BEAR" - 0x42454152.
   Sub-Selector: 12 - 0x000C
   Version: 1

   Hit Count: The number of hits that the client's filters allowed
   through.  0xFFFF should be used to indicate that the query should be
   terminated. This value is unsigned. Little-Endian