Correction to PrtChannelTypeTC

Correction to PrtChannelTypeTC

Correction to PrtChannelTypeTC

JK Martin jkm at
Sat Aug 24 13:05:00 EDT 1996


> I believe that there is an error in the PrtChannelTypeTC.  This
> has been pointed out in the past but has not been corrected in the
> draft.  If this is not correct, could someone please explain?
> The text should be as follows:
>    chPort9100(11),             --A bi-directional, LPD-like protocol
>                                --using TCP port 9101 for control and
>                                --TCP port 9100 for data.
>   chAppSocket(12),            --Adobe Systems, Inc.

I believe these descriptions are not quite accurate.

The "chPort9100" type is (and always has been, IMHO) a simple description
of what HP had started with its network-capable LaserJet (ie, JetDirect)
products.  This method involves a *single* stream (TCP) connection to the
device to transfer a print job, with modest "back channel" return of job
information.  It is *not* similar to LPD in any way, shape or form, nor
does it use a second stream connection.

Ironically, the "chAppSocket" channel type, on the other hand, has always
been described as being *exactly* as shown in your description for the
"chPort9100" type above.

I distinctly recall when Steve Zilles (Adobe) originally submitted the
chAppSocket channel type, since this type of technology is of critical
interest to my company (Underscore).  I had requested Steve to get me
some specs on this print job submission method, but have yet to receive
any to date.

Recently, I again requested information about chAppSocket, this time from
an old friend (Rick LeVine, formerly of Digital) who recently joined Adobe.
Rick has been trying to track down this info, but to date has not been

Perhaps representatives from Adobe and/or Hewlett-Packared can help
clarify this situation?


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