Subject: Re: [Sipping] use of SIP URI for announcements

From: Ben Campbell <[email-masked]>
Date: Wed, 22 Aug 2001 14:20:53 -0500

> My first choice is always to let users access servcies through things
> like web pages or vxml voice systems. Something like:
> 
> <a href="sip:sadasdapda09sd98as8da0-=[email-masked]">click here to initiate a
> super-foobar automated conference with feature wizbang turned on!</a>
> 
> THis means that I don't need to standardize anything, and a SIP client
> can access that service without needing to know about its existence
> ahead of time. So, I get the flexibility to design services that are new
> without requiring standardization for each one. Thats a big goal with
> sip, right?
> 
> Yet, I seem to get a lot of pushback on that....

That is exactly the intent behind rfc3087. You should not need to know 
the URL for a service in advance. The owner of the service hands it to 
you on a web page, a SIP redirect server, proxies you to it, etc.

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---

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 22 Aug 2001 15:15:46 -0400

Dredging up more old threads... my apologies for my burstiness on the lists.
I think this should be getting better now.

> -----Original Message-----
> From: Ben Campbell [mailto:[email-masked]]
> Sent: Thursday, August 09, 2001 12:35 PM
> To: [email-masked]
> Cc: [email-masked]; [email-masked]; 'Christian Huitema'
> Subject: Re: [Sipping] use of SIP URI for announcements
> 
> 
> I am very concerned about any trend (standard or otherwise) towards 
> assigning global meaning to URLs. I find a _convention_ even more 
> dangerous than a _standard_.

I agree. Conventions are problematic since you can't rely on them. So, I
still need lots of provisioning, and this will be a huge pain for user
generated scripts (like CPL) that don't even have an easy way to find out
how to talk to their voicemail server.

IMHO, URLs were not meant to be seen. The best uses of URLs are when they
are handed to you, with the enclosing context defining their meaning. In the
case of an HTML page, the hypertext rendered to the human indicates when to
use the URL. In voiceXML, the voice prompts played to the user help the vxml
server figure out what URL to use. URLs can be handed on business cards, in
which case the "surrounding context" that defines their meaning is evident
from the fact that its on a card - "use this URL to call me".

The next best thing is when URLs can be constructed because of a standard
that defines the meaning for a particular URL. mailto:[email-masked]
is definitely useful, and its only useful because I can pretty much rely on
this in any piece of software I write. If a server wants to send email to
the postmaster at a domain, thats how it formulates the URLs.

Conventions, on the other hand, mean that everything still needs to be
configured by hand, in which case, why is a convention needed in any case? I
have argued at the meeting as well, that this configuration may not even be
possible. Lets say my voip provider outsources voicemail to voicemail.com.
They have a convention for addressing voicemail inboxes. Now, if I want to
write a CPL script that forwards a call to voicemail, how do I know what URL
to use in my CPL script? With no standard, and no way to discover it, what
do I do? 

My first choice is always to let users access servcies through things like
web pages or vxml voice systems. Something like:

THis means that I don't need to standardize anything, and a SIP client can
access that service without needing to know about its existence ahead of
time. So, I get the flexibility to design services that are new without
requiring standardization for each one. Thats a big goal with sip, right?

-Jonathan R.

---
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
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