Dev Hack: Printing from a Map - Using Shell Commands Inside a Map Design

Contributed by Jake Hughes, Support Engineer at Pervasive Software, Inc.

A less well-known feature of the Pervasive Map Designer is its ability to embed shell commands within a map. This gives the Map Designer yet another edge of versatility and power while keeping the interface as simple as possible. As an example of it's usefulness, here are the steps for printing the output files of a transformation.

Printing from a transformation is a capability that can come in handy in certain situations. For instance, if some records are rejected, it could be good to immediately see a printout of the problem records to spot the errors. A printout of the output file could also be useful for a quick eyeball proofing check, or to show executives or managers an example of the output.

If someone needed printed output from a transformation, they might not be aware that such a thing is possible using Pervasive® Data Integrator™. However, since there is a fairly simple shell command to print a file, and the Map Designer can make shell commands, printing an output file from a map design is quite simple.

The variations in printers make it very difficult to directly embed the functionality, but that variability can be accounted for in the map design. The PCL section of the printer manual will have specifications on the correct options needed by the printer driver being used. Setting these options correctly in the map is essential. Because of that, higher-end printing hardware with good documentation is a requirement.

Three steps to print from a map:

1. Create, test, and save a map design that would create an output file compatible with your printer, generally with .prn as the file extension. Refer to the PCL section of the printer manual for specifications.

   If you would like a quick look at how this works, create a simple one-to-one map of the Tutor1.asc file provided with Pervasive Data Integrator. Most printers will print a simple delimited ASCII file although the formatting may be odd or parts of it may run off the page. Those PCL specs are the key to better formatted output.

2. Add a command line to one of the events in the map design. The AfterTransformation event in the Transformation and Map Properties makes the most sense since the output file will be fully created or updated at that point.

   Example 1: Shell("cmd /c copy " & Chr(34) & Targets(0).Filename & Chr(34) & " \\printserver\Example_Printer")

   This command line will print the target file, regardless of its name or location by using the metadata expression Targets(0).Filename. The filename parameter does not need to be changed to the exact name of the file. This parameter stays the same unless you would like to print the reject file, in which case you would change the metadata expression to Targets(2).Filename. Of course, a reject subsystem already has to be set up in the map design and a reject file created as part of the map before it will be possible to print the reject file. If you need to print the source file, Sources(0).Filename is the correct expression.

3. Adjust the server name, printer name, and path to the printer in the command line, and change the file parameter if a file other than the target file is to be printed.

   Example 2: Shell("cmd /c copy " & Chr(34) & Targets(0).Filename & Chr(34) & " \\texprint\Integration_Printer")

   This would print the target file called mytargetfile.prn to the Integration_Printer on the texprint server.

That's all there is to it. Execute the map and it will create the output *.prn file and the AfterTransformation event will trigger sending that file to the printer.

This is just an example of what you can do with this little-known feature of Pervasive Map Designer. Any similar task that can be performed with a shell command can be executed in the same way. Simply add the shell command line arguments to one of the triggering events using the sample syntax above as a guide.

One caution should be noted. Shell commands vary between platforms. This example syntax will work fine whether the transformation is run from the Map Designer design environment, called from a process step, or executed by the Pervasive Integration Engine as long as it is run on a Windows platform. The shell commands for executing via the Integration Engine on a Linux box or other supported platform might be a bit different. As long as you know your shell commands and adjust according to runtime environment, you should still be able to take advantage of this functionality.