Thursday, June 28, 2007

No new versions posted since March, so a few updates. One user sent a MSDOS .bat script for xdelta1/xdelta3 command-line compatibility, another sent a perl script for recursive directory diff, one user reports good performance for an in-kernel application (sample code), and some feature requests. Given the lack of bug reports, it's about time to take xdelta3 out of beta.

Several of you have requested a feature for supporting in-place updates, allowing you to apply deltas without making a copy of the file, which brings me to another bit of user feedback:And the funny part is, users were saying 5 years ago that Xdelta 1.x beats RTPatch. :)

I have to thank the IETF and previous work in open source (e.g., RFC 1950 – Zlib, RFC 3284 – VCDIFF) for making this possible. Zlib bills itself "A Massively Spiffy Yet Delicately Unobtrusive Compression Library (Also Free, Not to Mention Unencumbered by Patents)", and in fact Zlib inspired Xdelta's API from the start (it's "unobtrusive"). Let's not forget Zlib's other main advantage (it's "unencumbered"). As for the the previous request (in-place updates), interest is strong but patents could become an issue.

Multi-threaded encoding/decoding is another frequent request. The idea is that more CPUs can encode/decode faster by running in parallel over interleaved segments of the inputs. That's future work, and probably a lot of it, but I like the idea.

Xdelta 3.0q has 11,480 downloads. It's you the user that feeds open source, and thanks for the great feedback!

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