[avahi] Re: [avahi-commits] r637 - /trunk/service-type-database/service-types

[Lennart Poettering]

On Mon, 26.09.05 18:30, Marc Krochmal (marc at apple.com) wrote:

> Hey Lennart,

Hi!

> 
> I'm now getting your commit e-mails and I noticed this check-in.  I'm  
> a little concerned about another source of service types popping up,  
> because DNS-SD becomes a lot yes useful if everyone is using  
> different service types.  It makes it much more difficult for  
> products to interoperate if developers must search in multiple lists  
> to find the service types they should use.

Our list is not intended as an official service type list like the one
you maintain on http://www.dns-sd.org/ServiceTypes.html

Instead this is used execlusively for improving user experience in
network browsing tools. "Web Service" is easier to understand from a
user perspective than "_http._tcp." Our list handles i18n and doesn't
contain any information about TXT records. It's not a documenation for
developers but only service type translaton table for user
interfaces. Due to this the wording is not the same as in your
list. e.g. in your list we find the description "IPP (Internet
Printing Protocol)" for _ipp._tcp. In our list this is available as
"Internet Printer". When compiling Avahi the list is converted into to
a gdbm file, and installed that way. To say it in FHS terms: the list
is installed to /usr/share/avahi/ and not to /usr/share/doc/avahi.

Our list is only updated when someone comes across a service not yet
contained in the list in the first place.

We could certainly agree on moving this list out of the scope of Avahi
to something more global, like dns-sd.org.

> I'm also wondering what you mean by the comment that says dns-sd.org  
> "is not a source that complies with the criterion".  The list on dns- 
> sd.org doesn't really have a license because it's just a list of  
> service types.  If you feel like you can't use this list, then I'm  
> sure we'd be willing to slap a BSD style license header to the top of  
> this page.

Yes, A BSD license would be nice for that. Does the list exist in a
form that is more easily parsed for generating a gdbm file?

In case you make the list available under BSD we would surely copy it
from time to time into our database.

> Regarding the RSS types, I'm wondering why we need two different  
> types for this.  Wouldn't "_rss._tcp" be enough?  Can't the protocol  
> figure out what version to use?
> 
> As an example, we don't have an _http10 and _http11 type, and there's  
> ssh version 1 and version 2, but we only have a single _ssh type.
>
> I think RSS is important enough that we should think about this a  
> little first, because whatever we decide, it will be in use for many  
> years, and it's always a pain if applications that used to browse for  
> the *wrong* type then have to transition to the new type by browsing  
> for both for a little while.  I hate it when that happens.  :-)

Hmm, HTTP 1.0/1.1 are completely upwards and downwards compatible as
far as I know. However this is not true for RSS 0.91 vs. RSS
2.0. That's why I used different service types for them.

I actually introduced  this service type because someone on IRC showed
interested in adding support for it to some RSS aggregator app. We
quickly agreed that _http-rss091._tcp, _http-rss20._tcp  and finally
_http-atom._tcp would make some sense. Since we couldn't find a trace
of a RSS DNS-SD type on the internet yet, we simply went on and added
it to our list. 

Using just "_rss._tcp" instead of "_rss-http._tcp" doesn't look
logical to me, since the protocol used IS actually HTTP, only the
resource referred to is RSS. This is somewhat similar to
"_ssh-sftp._tcp" i guess. 

What do you think about this? We can certainly agree on a common name,
since there is no real softwaring actually using it available yet.

BTW: May I politely ask you to add a link to Avahi on either
dns-sd.org or multicastdns.org, the way you already added a link to
those Java, Ruby or Python implementations?

Thank you,
      Lennart

-- 
Lennart Poettering; lennart [at] poettering [dot] de
ICQ# 11060553; GPG 0x1A015CC4; http://0pointer.de/lennart/