Dedicating a port to printing on the surface sounds good. But, not
being an expert on firewalls, I ask is that a problem? My understanding
is that some firewalls keep things under control by not allowing
certains ports to be used (i.e. nothing can be used unless explicitly
permitted.) Is this going to be a problem in an inter-enterprise
environment? Could someone with a better understanding of
firewalls comment on this?
To: ipp%pwg.org @ interlock.lexmark.com @ SMTP
cc: (bcc: Don Wright)
From: harryl @ vnet.ibm.com>" <harryl%VNET.IBM.COM at interlock.lexmark.com
("Harry Lewis) @ SMTP
Date: 11/18/96 05:18:41 PM
Subject: Proposed well known port for printing via HTTP
In the IPP/1.0 draft version 0.91 (11/14), on PDF (no revision marks) line
474, there is reference to a sample (hypothetical) IPP Job name. The name
is made up of the http protocol indicator, the IP address of the printer, the
"port" and the printer name. Here, the port is an arbitrary example.
I would like to propose we attempt to standardize a well known port for
printing via http. The notion would be that whatever we define as printing
via http will work over http well known port 80 (along with everything else
that flows via http), but, if directed to well known port (say 380 - assuming
this port is not already defined), then only PRINTING, not any other form of
http, would be expected.
This proposal closely follows the motivation described in the internet draft
<draft-mellquist-web-sys-00.txt> submitted June 1996, which recommends
well known port 280 for SNMP over HTTP. Read (3) of this draft for a more
thorough dissertation on the merits of this approach.
As for text to add to the IPP draft (tonight), I suggest a new head level
created between 2 (Distributed Printing) and 3 (IPP Objects) called
2 (Printing via HTTP). Probably, a lot could be lifted from Roger's document
and put into this section, I'm not going to try and flesh this out here.
Also, in this section, however, we should put some words like...
"It will be suggested (in section 5) that Clients identify Printer objects
using an HTTP type URL. One element of this proposal will be to further
recommend the establishment, through IANA, of a well known port (380
recommended) for printing via HTTP. The purpose of this well known port
would be to distinguish printing from non-printing content. While any
acceptable HTTP content could be inter-mixed over HTTP well known port 80,
only HTTP printing would be acceptable on port 380.
The remainder of this draft will define the IPP content for HTTP printing,
including IPP objects, operations, naming and attributes."
Harry Lewis - IBM Printing Systems