In discussing WBMM (which has some similarities to PSI), I advanced the premise that Web Based management would use the infrastructure (access path, proxies etc) that enterprises have established for user web access. I suggested that this was parallel to what PSI was doing, since I thought that that indeed, was the way that PSI would allow deployment without requiring firewall reprogramming, special proxy setups, etc.
However, Ira corrected me and observed that:
PSI implementations MUST ONLY use the (future) IANA-assigned
PSI "registered port" (a number greater than 1024 for a vendor
defined protocol).
PSI implementations (even by administrator configuration)
MUST NOT ever use port 80.
and further indicted that to use port 80 for things other than human driven browser clients would violate guidelines being established by IETF/DMTF/W3C.
However, this non use of port 80 for PSI is not clear in the specifications. There is a statement relative to URL examples to the effect that the port 80 indicated would be replaced by an IANA to be assigned number; but that does not appear to be a ban on the use of port 80. And the section on firewalls in the Application Guide is empty.
I believe that requiring any location that is to support a PSI Client or PSI Target Device create a new path through the firewall will serious affect the potential adoption of PSI. One may observe that assigning port 631 to IPP did very little to allow its use as an Internet Printing Protocol. In presenting PSI to NetSilicon customers, the ability to use the existing port 80 facility is a very important factor.
Therefore, I would like some clarification about what the intent in specification really is, and what the position of the working group is.
Many thanks.
Bill Wagner, NetSilicon/A Digi International Company
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