Subject: Re: IPP> What is it we really need?

From: [email-masked]
Date: Mon, 6 Jan 1997 13:49:03 -0500

Classification:
Prologue:
Epilogue:

Randy, can you help us all to understand the "cost" issues?  I for one do not
know what the cost of implementing HTTP or HTTP-Lite would be.   What I do know
is that there is lots of HTTP server code out there that I can re-use, thus
substantially shortening my development time.  Furthermore, if a printer
manufacturer puts HTTP in the printer to support configuration (as Tektronics
has and others have said they will do) then it will be there anyway, so why not
use it? And, while I agree that we need to be careful about tying printing
protocols and the web together, I would hate to see us re-inventing (and
reimplementing) everything that already exists in HTTP  when we need it.
Finally, I think that the most compelling argument is the one of wanting to see
ubiquitous support across the major industry platforms -- both as clients and
as print servers.  HTTP  WILL BE supported on all of the interesting clients
and server platforms!  How do we convince the platform vendors to build support
for a new protocol???

---------------------- Forwarded by Roger K Debry/Boulder/IBM on 01/06/97 11:36
AM ---------------------------

        ipp-owner @ pwg.org
        01/06/97 11:00 AM
Please respond to [email-masked]@internet

To: ipp @ pwg.org@internet
cc: moore @ cs.utk.edu@internet
Subject: Re: IPP> What is it we really need?

Keith Moore wrote:
>
> ..snip..snip..
>
> If nothing else, printing protocols and the web each need to evolve
> separately; we need to be very careful about how we tie them together.
>
> Keith

I think we need to decide whether or not we are doing IPP or WPP
(Internet Printing Protocol or Web Printing Protocol)

The statement made by Keith (included in this msg above) I think is
crucial. I haven't thought about the ramifications (and permutations)
of tying a printing protocol to another N-numbered set of technologies
like HTTP, LDAP, CGI, and HTML (if we decide to use forms). It looks
like it might be more than we want to get into, at least from an
interoperability and maintenance standpoint.

At any rate, we need to think about someone that wants to do
printing across the internet, but does not want to be burdened with
the cost of implementing HTTP (or even HTTP-lite).

In this same vein, it would be very difficult to account for IPP
usage if we "hide" the IPP protocol within a set of HTTP accesses,
using the HTTP TCP port number, for example. This echoes the
ideas expressed by Alex earlier, and would also allow net-admins to
create policies that enable/disable HTTP and/or printing as
separate applications, something that sounds desirable IMHO.

Randy
(Good luck sorting this out in New Mexico ;)

--
Randy Turner
Network Architect
Sharp Laboratories of America
[email-masked]

---

From: Randy Turner <[email-masked]>
Date: Mon, 06 Jan 1997 10:59:11 -0800

> and server platforms!  How do we convince the platform vendors to build support

At least for printing, we ARE the platform vendors, so we would supply
IPP service
layers for the platforms we are interested in supporting. We also have
most (if not
all) of the major commercial computing platform vendors as part of the
committee, so
the people we have to convince would basically be ourselves.

Like Keith said earlier, there is alot existing code out there, but that
doesn't
mean its necessarily the right place to start standardizing a printing
protocol.
Also, the existing code will not function without IPP enhancements, and
the bulk of
the work left to do (with regards to design and implementation) have to
do with
the protocol thats layered on top of TCP or HTTP. 

There are also alot of other issues that may come up and bite us when we
start
layering on top of HTTP, like caching, proxies, and security models. It
may end
up that the usage model of how HTTP is used for the majority of the
industry
(Web page browsing) may conflict with how we want to implement printing.
I heard
some very complicated usage models come up at the HTTP working group
meeting in
San Jose, with regards to caching and proxying. These algorithms and
configurations
may conflict with our simple requirements of submitting a print job and
checking
status. There are also authentication and authorization issues with
regards to
HTTP that might not work the way we want them to for printing.

I guess what I'm saying is that if you select HTTP as the transport, you
have to
accept alot of the baggage and disadvantages of using HTTP, along with
the good
aspects. And that extra baggage of issues and dependencies may not
balance out
equally with the advantages of existing code. It may be a very hard pill
for the
committee to swallow.

Randy