Review: Altova DiffDog 2005

• By Mike Gunderloy
• January 19, 2005

Altova DiffDog 2005 Professional Edition
$129
Altova, Inc.
Beverly, Massachusetts
(978) 816-1600
www.altova.com

I've reviewed XMLSPY and the other XML-oriented products from Altova several times over the years, but I've always thought of them as strictly an XML tools vendor. So I was a bit surprised to get the press release announcing their latest product. DiffDog 2005 is a visual diff and merge application. It does work (and well) with XML files, but it also works with other files and directories. Despite being a slight departure from the other tools that the company has produced, this is a well-done piece of software that's a pleasure to use.

When you start DiffDog, it presents an attractive Windows interface that XMLSPY customers will recognize as matching the GUI standards set by the other Altova products. You can open multiple comparison windows and display them in either a MDI interface or a tabbed interface at the same time. Each window can do one of three types of comparison: file, directory, or XML. A file comparison, of course, shows the differences (color-coded) between a pair of files. Directory comparisons let you see the differences between two directories. XML comparisons also compare a set of files - but in an XML-aware fashion. That means it understands DTDs, white space, reordered elements, and other features of XML.

There are lots of nice little touches here. In addition to moving changes from either version of a file to the other, you can actually edit the files directly in the diff windows. You can use Altova's familiar grid view for XML files. You can specify which file types to consider as XML when doing a directory comparison.

Even on large files or directories, the tool is quite snappy. There's also a command-line interface so you can tie DiffDog in to your source code control system (or anything else). One nice touch there is that there's a "quiet" mode where you call the command-line version and get back text output that you can process further as part of a batch. If you'd like to give it a spin, you can download a 30-day trial copy. There's also a Standard edition at $69 that lacks the advanced XML features.