Microsoft has posted a paper discussing their new Delta Compression API , which looks like it is a byproduct of their Windows Update program, a place where delta compression is probably pretty useful.
The idea of performing data compression by doing diffs between files is not a new one, but I do think it has been underutilized. There are a few projects out there, such as Deltup , which is basically a patch system. Microsoft has published a paper on this in the past, Using Binary Delta Compression (BDC) Technology to Update Windows Operating Systems .
I’ve even seen some nice code on the CodeProject site, a project called A Generic, Reusable Diff Algorithm in C# - II .
Still, when Microsoft puts it in an API, well, it’s time to sit up and pay attention, because it means you might be able to make easy use of this in your programs - although considering the skill with which Microsoft normally designs APIs, this isn’t likely.
But this looks pretty comprehensive, so if your diff needs are confined to the Win32 platform, maybe you ought to take a look.