Print Server Appliances that Spool?

man_ls asks: "I have recently run across the need for a network print server appliance, that can spool the data it is given and send it slower than 10 mbps to the printer. A client of mine has an Intermec label printer, with an internal processor too slow to accept data directly from the network without being buffered. Due to the system the client is running (OpenVMS) it must be connected to the network, it can't be local on one of the servers. Any ideas of a small print server box that can act like a spooler?"

Comments

Re:Dedicated servers

[Zocalo]

We had that too. We flashed the EEPROM to the latest firmware on the afflicted ones (four or five out of several dozen) and the couple that didn't stop crashing we RMA'd for replacements which worked fine - problem solved. Since there were similar firmware revisions on the problem kit we put it down to a coding issue in the firmware. We also noticed that not all the potentially susceptible kit was having problems when we went around and updated all the firmware as part of our Y2K effort, so you might want to investigate an upgrade, just in case it's a similar issue.

Apart from that batch, they've been rock-solid - the one I've got at home hasn't been rebooted since I installed my current UPS which was... 940 days ago according to the Netport.

I think I used to have your job...

[Zarf]

A client of mine has an Intermec label printer, with an internal processor too slow to accept data directly from the network without being buffered.

I ended up writing a bunch o' custom Intermec Printer Drivers for linux and using one of their prolific Linux boxen to act as a spooling server. Wasn't that bad to work out. The hardest bit was writing the Intermec drivers... I had to reverse engineer those. Fortunately it was a custom app and only printed a half dozen types of documents.

If you're interested I could share the "reverse engineering" technique... more of a quick hack actually. Heck, the whole thing was a clever hack... I hate clever.

Re:I think I used to have your job...

[Zarf]

Intermec printers are a breed of printers that talk IPL or Intermec Printing Language. There are large manuals on IPL and a programmer is certainly welcome to use them to develop Intermec printer drivers. Therefore I assume that Intermec isn't terribly upset with people developing their own software to run on their printers.

It is possible therefore for a programmer to work just like they would with postscript. You could create a converter for some other format such as HTML and dump that to IPL. That's a lot of work but it's the most versitile way... But you can create a custom "driver" again using the term driver very loosely.

The quick and dirty hack I used relies on the fact that the Intermec thermal printers were used to print only a half dozen different types of documents. Each of these prints worked off of a third party "template" in a third party "template" language. The template could be created in the third party application and printed to an intermec printer... only the data in the IPL changes over time.

The problem is that as far as I know there is no such thing as an IPL template program. I needed the template in IPL not some other template language. Someone could write one I suppose. I wasn't about to. So I used the Windows application (it had some amazing copy protection software on it but was horribly inflexible for the user) and printed out one of each type of document. I then set up a Linux box in the development area with a port listener and set up the windows box to print to the Linux box instead of the Intermec printer.

I captured the print data transmitted for each document and looked the output looking for the data that had to change with each print. Fortunately I was lucky and didn't have to change much of the IPL ... the fields were in plain text. So I set the values in the fields to "**date**" or "**UPCBarCode**" and such things.

I saved each IPL print to a file and wrote a PERL program to wash this data each time a print request was made from another application and dump it out to the Intermec printer emulating the way that the Windows application talked to the printer. The result ended up evolving into a custom print application... and one that didn't use the Unix print facilities and so we get to call it a "print driver" to make is sound more important.

This doesn't address the original post directly but I guess but it should illustrate the idea of how to hack around with a linux box to masquerade as another network device and how to get what you want out of it.

I just went back and re-read the original post. His problem has little to do with IPL or Intermec printers in general... he should simply put the Intermec on a slower network connection. The "right" answer is to use a spiffy switch like a Cisco something-or-another that has 10Meg ports on it the result is to create a deliberate bandwidth bottle neck in one area of the network. This will force the communications to be slower and won't require changing software. This imples hacking around with IOS or the routers to set ports to slower settings and possibly tweaking buffer memory allocations...

Barring the right answer due to lack of know how, permission, equipment, or money... the hack could be to do something like what I did and put a bunch of sleeps in the code sending chunks of IPL at a slowed down rate... and that is evil... but it would work.

Here

[FreeLinux]

When it comes to network printers and print servers the authority has always been Hewlett Packard. You'll find what you need (is a 7GB spool enough for labels? ) here but at nearly US$2,000 I would think that you could build a Linux box running CUPS and Samba for a lot less.

Trying to answer your question

[bill_mcgonigle]

I think most of the respondents here are missing the point when they recommend a cheap COTS print spooler - they rarely have the rate limiting feature you need.

Why not just setup a simple print spooler (samba/netatalk) which will deliver files to a queue. Then you can write a little perl script to read the file in at a known data rate (while ... read buffer size ... sleep ... print) out to the printer device. Delete the spooled file when it's done. You'll probably need to set binmode on your filehandles.

Low Tech Solution

[orn]

Just find a 10bT hub and hook one end to your 10/100 switch and the other to your printer. Let TCP handle all your buffering for you.

Those hubs are probably sitting on the trash pile of countless IT departments right now. You might be able to pick one up on e-bay...

Rudy

Re:Dedicated servers

[morzel]

Next time you produce a rant, please be sure to include at least one qualifying answer in your rant.

Poster was looking for a print spooler (not a print server), that has some kind of configurable output rate throttling; none of which is supported in the devices you listed.

Offtopic question related to printing

[RGRistroph]

I would like to be able to use linux to emulate a printer. That is, I would like to be able to take another computer, hook it to my parallel port, and then have that computer think for all practicle purposes that it had a printer on the other end. My computer could simply log what was being printed, or forward it to a different printer, or whatever.

Has anyone here ever done this ?

The purpose is to make a linux box that can emulate an older printer to a legacy computer, take the files to be printed and possibly modify them and send them to a modern printer (such as a network or USB interface).