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Re: How to get bytes of printed file using Win32_PrintJob

29-Nov-08 10:53

Hii all..
I am creating a small application that supposed to monitor printing activities. I used Win32_PrintJob and successfully get the informations of printing process such as DocumentsName, PagesPrinted,TotalPages,Size,etc.
I store these values into database as printer log.

But, I have some difficulties in getting the bytes of printed files. Is it possible to do that using Win32_PrintJob?
I want to get these bytes to store it into database, so that the admin can see the content of printed files in the next time.

Thanks before for the answers.

0x3c029-Nov-08 23:34

Re: How to get bytes of printed file using Win32_PrintJob

29-Nov-08 23:34

I don't think there's an easy way to get the print job bytes using WMI. Try another, faster approach. Get every print queue using the LocalPrintServer.GetPrintQueues() method, iterate from 0 to the return value of the PrintQueue.NumberOfJobs property of the individual print queue, and use the returned PrintSystemJobInfo class from the PrintQueue.GetJob() method. There should be a PrintSystemJobInfo.JobStream property which will give you the stream of the job's data. All of these can be found in the System.Printing namespace, which you need to add a reference to (ignore what the MSDN page says about Vista, it works on XP just as well)

Wahyu Hidayat1-Dec-08 16:12

Re: How to get bytes of printed file using Win32_PrintJob

1-Dec-08 16:12

1 LocalPrintServer lps = new LocalPrintServer();
2 PrintQueueCollection pqc = lps.GetPrintQueues();
3 PrintSystemJobInfo pj;
4 foreach (PrintQueue pq in pqc)
5 {
6 pj = pq.GetJob(pq.NumberOfJobs);
7
8 }

As u sugggested, I create above code. But, I get an error at 6 line. With error description "Value cannot be null. Parameter name: printingHandler".
Do you have some suggestion? Or could you give me simple code that show your suggestion will work.

Thanks...

Wahyu Hidayat1-Dec-08 19:06

Re: How to get bytes of printed file using Win32_PrintJob

1-Dec-08 19:06

private PrintSystemJobInfo GetInfo()
{
LocalPrintServer localPrintServer = new LocalPrintServer();
PrintQueue q = LocalPrintServer.GetDefaultPrintQueue();
q.Refresh();
foreach (PrintSystemJobInfo pj in q.GetPrintJobInfoCollection())
{
return pj;
}
return null;
}
PrintSystemJobInfo pj = GetInfo();
int len = pj.JobStream.Length;

I use Windows XP Sp2
When executing len = pj.JobStream.Length an error occur "Object reference not set to an instance of an object."

Is JobStream works in XP? Because I read that it works on vista only.

0x3c01-Dec-08 20:13

Re: How to get bytes of printed file using Win32_PrintJob

1-Dec-08 20:13

If it only worked in Vista, then a different exception would have been thrown. As it is, you seem to be dropping past the foreach() for some reason. You do have something printing, even if only to a dummy printer, which isn't connected to the computer?
On the other point, I looked through the System.Printing.PrintQueue class with Reflector, and there doesn't seem to be any code which checks if you're running Vista, unless it relies on some new APIs, but I haven't seen any

Wahyu Hidayat4-Dec-08 5:57

Re: How to get bytes of printed file using Win32_PrintJob

4-Dec-08 5:57

I use both of connected printer and dummy printer. but the PrintSystemJobInfo.JobStream always return null . Any suggestion?

0x3c04-Dec-08 9:59

Re: How to get bytes of printed file using Win32_PrintJob

4-Dec-08 9:59

There is nothing which could cause the JobStream property to return null. Try something like this for the GetInfo() method of yours:

private PrintSystemJobInfo GetInfo()
{
    LocalPrintServer localPrintServer = new LocalPrintServer();
    PrintQueue q = LocalPrintServer.GetDefaultPrintQueue();

    for(int i = 0; i < q.NumberOfJobs; i++)
    {
        return q.GetJob(i);
    }
    return null;
}

On the off chance, step through the code and check the NumberOfJobs property. Is it set to zero?

Wahyu Hidayat6-Dec-08 5:15

Re: How to get bytes of printed file using Win32_PrintJob

6-Dec-08 5:15

I've tried your code. When I executing the return q.GetJob(i);, it apprears error :
"An exception occurred while creating print job information. Check inner exception for details."

I search the inner exception, and found "Object reference not set to an instance of an object."

In my previous code:
private PrintSystemJobInfo GetInfo()
{
LocalPrintServer localPrintServer = new LocalPrintServer();
PrintQueue q = LocalPrintServer.GetDefaultPrintQueue();
q.Refresh();
foreach (PrintSystemJobInfo pj in q.GetPrintJobInfoCollection())
{
return pj;
}
return null;
}

PrintSystemJobInfo pj = GetInfo();

From pj I can get the printing information such as DocumentName and NumberOfPage. But when I try to get value from of JobStream, the error "Object reference not set to an instance of an object." apprears. Seems that the value of stream is null.

0x3c07-Dec-08 3:23

7-Dec-08 3:23

There's only one thing more that I can think of. Stick with your original GetInfo() and after you get the PrintSystemJobInfo returned by GetInfo(), call the Refresh() method before you access the JobStream property. Something like this:

PrintSystemJobInfo pj = GetInfo();

pj.Refresh();
Console.WriteLine(pj.JobStream == null);

If that doesn't work, then I don't know of any other method to do what you originally intended

re Code

mutafa8129-Nov-08 10:41

mutafa81

29-Nov-08 10:41

Hi all

Now i finished My program, got it's EXE works.

is there is any way to get the code from EXE

and how to protect my EXE from this

Thank you..

Pete O'Hanlon29-Nov-08 10:47

Pete O'Hanlon

29-Nov-08 10:47

mutafa81 wrote:
is there is any way to get the code from EXE

Yes - you can disassemble the code.

mutafa81 wrote:
and how to protect my EXE from this

You might want to try an obfuscator. It won't stop you getting the cod out, but it will make it bloody hard to read.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

My blog | My articles | MoXAML PowerToys

Paul Conrad29-Nov-08 13:48

Paul Conrad

29-Nov-08 13:48

Pete O'Hanlon wrote:
You might want to try an obfuscator. It won't stop you getting the cod out, but it will make it bloody hard to read.

I agree. Though I know of an obfuscator that can cause Reflector to crash when trying to disassemble the obfuscated code.

"The clue train passed his station without stopping." - John Simmons / outlaw programmer

"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

"Not only do you continue to babble nonsense, you can't even correctly remember the nonsense you babbled just minutes ago." - Rob Graham

PIEBALDconsult29-Nov-08 15:12

PIEBALDconsult

29-Nov-08 15:12

That sort of thing isn't worth worrying about.

Thomas Weller29-Nov-08 17:51

Thomas Weller

29-Nov-08 17:51

Nah, I don't agree.
While this might be true for most apps, it's surely not for all of them. It entirely depends upon what's inside your code (e.g. company-specific algorithms that are protected by law).

At least you have to know about the problem to be able to make an informed decision about it.

Regards
Thomas

www.thomas-weller.de

Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning.
Programmer - an organism that turns coffee into software.

Paul Conrad30-Nov-08 6:38

Paul Conrad

30-Nov-08 6:38

PIEBALDconsult wrote:
That sort of thing isn't worth worrying about

Not if you have intellectual property that you do not want the competition to find, or a client to have some one dig around in your work and sell it to someone else.