[gnome-network]SrvLoc research.

["Miguel A. Arévalo" <marevalo marevalo net>]

Hi all,

a week later I've been able to do some service location protocols 
research, my plan is to do a study of the different protocols in use in 
order to develop a rich enough API for supporting all of them.

Ok, here they go some of my notes on the first aproach:

* DNS ( static / zeroconf) : http://www.faqs.org/rfcs/rfc2782.html
	Architecture:
		Centralized DNS (with dynamic option) / Distributed mDNS
		Sync API?
	You ask for:
		service && protocol && domain
		_kerberos._udp.company.com
	You get:
		host fqdn, priority, weight, port
	Users now:
		smtp (dedicated MX), jabber s2s, kerberos, Windows 2000

Comments:
Quite simple <-> little flexibility
There can't be different real services for the same service id on the 
same domain, for example, only one database per domain.
Cannot add any user friendly descriptors.


* SLP : http://www.srvloc.org
	Architecture:
		Multicast , Register Agent , Directory Agents
		Async API , user defined attibutes
	You ask for:
		service , domain or host , port , attribute filter
	You get:
		full service URL :
		service://host.fqdn.com:port/path;attr1=val1;attr2=val2
	Users now:
		KDE RD, Novell >=5, Axis, CUPS

Comments:
Great flexibility.
Async API good from the usability point.
service URLs are great


* SAP :
	Architecture:
		Seems to be only for IPX networks.
	Users now:
		Novell over IPX (mainly < 5)
Comments:
¿Is gnome-network going to support IPX? If that is the case I will try 
to do some research on it.


* NetBIOS ( NBT browsers / WINS ) :
	Architecture:
		Multicast / Centralized
	You ask for:
		Resource type , netbios name
	You get:
		Resource type , netbios name , IP Address
	Users now:
		Windows NT, Samba
	
Comments:
As far as I see only three services are interesting:
	- File sharing ( SMB/CIFS )
	- Printing ( SMB/CIFS )
	- Remote desktop ( RDP )
All the shares (incl. printers) are on the same NetBIOS name
Implement SMB/CIFS queries for browsing shares?
Mapping of shares: netbios-ssn://NBTSERVER\Share?
It's still a mistery to me how the Terminal Server client finds the 
server. Hints?


So:

- I think we should support at least DNS and SLP and then proceed with 
NetBIOS after that.
- I think that an asynchronous API would be the best (in order to map 
correctly SLP and from a usability point of view).
- Should we go with the service URL or with a set of (attribute,value) 
pairs?

Ok, now I will try to get a good in depth sumary of the DNS and SLP API 
during this week, also will look at one of the different SMB browsers to 
get a good idea on how they query the SMB protocol.

Questions ?

Regards,

Miguel A. Arévalo