Printing from a .NET Service [closed]

Answer 1

Printing from a service is a bad idea. Network printers are connected "per-user". You can mark the service to be run as a particular user, but I'd consider that a bad security practice. You might be able to connect to a local printer, but I'd still hesitate before going this route.

The best option is to have the service store the data and have a user-launched application do the printing by asking the service for the data. Or a common location that the data is stored, like a database.

If you need to have the data printed as regular intervals, setup a Task event thru the Task Scheduler. Launching a process from a service will require knowing the user name and password, which again is bad security practice.

As for the printing itself, use a third-party tool to generate the report will be the easiest.

Answer 2

I've done it. It's a pain in the A*s. The problem is that printing requires that GDI engine to be in place, which normally means that you have to have the desktop, which only loads when you're logged in. If you're attempting to do this from a Service on a Server, then you normally aren't logged in.

So first you can't run as the normal service user, but instead as a real user that has interactive login rights. Then you have to tweak the service registry entries (I forget how at the moment, would have to find the code which I can do tonight if you're really interested). Finally, you have to pray.

Your biggest long term headache will be with print drivers. If you are running as a service without a logged in user, some print drivers like to pop up dialogs from time to time. What happens when your printer is out of toner? Or out of paper? The driver may pop up a dialog that will never be seen, and hold up the printer queue because nobody is logged in!

Answer 3

I think we are going to go the third party route. I like the XSL -> HTML -> PDF -> Printer flow... Winnovative's HTML to PDF looks good for the first part, but I'm running into a block finding a good PDF printing solution... any suggestions? Ideally the license would be on a developer basis, not on a deployed runtime basis.

Answer 4

If you can output to post script some printers will print anything that gets FTPed to a certain directory on them.

We used this to get past the print credits that our university exposed on us, but if your service outputs to a ps then you can just ftp the ps file to the printer.

Answer 5

Printing from a Windows service is really painful. It seems to work... sometimes... but finally it craches or throws an exception from time to time, without any clear reason. It's really hopeless. Officially, it's even not supported, without any explanation, nor any proposal for an alternate solution.

Recently, I have been confronted to the problem and after several unsuccessful trials and experimentations, I came finally with two viable solutions:

• Write your own printing DLL using the Win32 API (in C/C++ for instance), then use it from your service with P/Invoke (works fine)
• Write your own printing COM+ component, then uses it from your service. I have chosen this solution with success recently (but it was third party COM+ component, not own written) It works absolutely fine too.