Quick questions about ed2khash
 

I saw that there are UPs that pass urn:ed2khash:xxx queries.
1. Is the process with urn-ed2k the same as with urn:sha1? we send a queryHit stating we have the file and it begins DL with HTTP-GET or is it different?
2. Which Gnutella clients (i think Raza, but i don't know if anyone else) send these queries (supports ed2k)?

Thanks,
Snayit

It must be one of the multi-protocol clients, probably Shareaza or maybe Morpheus etc. It's not a standardized or documented feature.

In theory, a HTTP GET request for

/uri-res/N2R?urn:ed2khash:...

should work. I think you only see such queries if you don't implement the Query Routing Protocol (QRP). At least, it wouldn't be a good idea to pollute the query routing table with those ed2k hashes. For such purposes a DHT should be used. LimeWire, for example, does not route urn:sha1 queries any longer.

Gnutella will sooner or later be extended with a DHT for such purposes.

I think you are right, i saw the GET messages
 

with the urn:ed2khash:xxx that you mentioned, but i did not understand the rest of your response - why doesn't LimeWire route urn:sha1 queries? What does it mean?

I'll read more about the DHT to figure our more. Thanks,
Snayit

You'll have to check the GDF archive for the details. However, the LimeWire guys are convinced that such queries are bad. For example, it's bad for dynamic querying because searches for exact resources are less likely to succeed than keyword searches. Maybe LimeWire still supports them for TTL=1, Hops=0 but in the general case it doesn't.

The support for urn:sha1 searches in Gnutella was more or less a hack because the QRP hashcode for "urn:sha1:..." is simply added to the routing table for each file you share. This means the table will contain much more items than normally if it hashed only keywords. Therefore, there are more false-positives which means more traffic and less scalability.

When does Shareaze use ed2khash?
 

If it's an ED2K DL - it uses ED2K protocol, right? if so, than how come it uses Gnutella's protocol to query urn:ed2khash?

Thanks,
Snayit

You have to look at its sources or ask the developers to get a definitive answer. Such queries might be caused by ed2k or magnet-links with such a hash. There's of course an urn:sha1 equivalent for each of them but you cannot calculate it before you have the file.

In theory you can use any urn-scheme you like and it will work as long as there are enough peers that support it. Using ed2k hashes is certainly questionable since ed2k has its own network which would be a much better choice for this. Maybe they added it because too many Shareaza users got kicked from the ed2k network.

Shareaza is widely known to do a lot but little correctly and it wouldn't be the first time that it bugged Gnutella like parasite. Exploiting the name "Gnutella" for publicity, abusing Gnutella to bootstrap the infamous G2, free-riding GWebCaches, downloading from Gnutella peers but blocking uploads to them are the well-known examples.