Saturday, April 04, 2009

UUIDs and 2D Barcodes

I wrote about UUIDs (Universally Unique IDs) earlier and speculated about some of their possible uses. One of them, I thought, would be the ability to link them to real-world entities through corresponding 2D barcodes, which are a cool innovation in their own right.

So this weekend, I spent some time trying to combine both technologies.

Apparently, there is a standard called PDF 417 that defines 2D barcodes. There are Open Source encoders and decoders that implement this standard.

I downloaded the Pdf417lib encoder software from SourceForge. It's just a simple Java class that you compile and run, so it's not particularly complex to use. Of course, it's not the best-documented piece of software around, but then again, I can't look an Open Source horse in the mouth. I just wish I knew what the various parameters were so I could tune them. As it was, I tried fiddling around with some of them and settled for something that sort of worked. The main() method of the class is written to generate a PostScript file corresponding to any text string that is fed to it, so all I had to do was pipe in a fresh UUID as that text string, using the java.util.UUID class and its randomUUID() method. I didn't have the appetite to do much more than prove the concept.

I wrote the following bit of code based on the main() method of the Pdf417lib class itself. This is what my test class looks like:

The critical lines here are:

Pdf417lib pd = new Pdf417lib();
pd.setText( UUID.randomUUID().toString() );

I compiled and ran the class quite simply:

$ javac
$ java TestUUIDBarcode
$ ps2pdf test1.pdf

The "ps2pdf" command, as can be guessed, converts PostScript files to PDF.

I ran this once more just to check that I wasn't getting the same barcode again. The UUID generation is meant to be random, so I should get a new barcode every time.

Here are two of them. I hope they look different enough.

So that's what UUIDs look like when converted into 2D barcodes. All courtesy a standard JDK function and an Open Source library. During the dot-com era, someone could have started a company based on this idea ;-).

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