Online Patching Systems?

Master_Flash asks: "My company is preparing to distribute an online Windows application that will change over time (don't they all?). We been evaluating online patch systems. There are a number of commercial applications out there. Some look good: RTPatch from PocketSoft, ASTA Binary Patcher, and Necromancer's FlashUpdate. Has anyone had a positive experience with these or other applications? One other idea we had was to use CVS as a patching system. While CVS isn't technically a binary patch it does a great job at checking on which files need to be updated. Most of the files we have are small and change infrequently, so CVS could work. Opinions and guidance are welcome."

Comments

Roll Your Own!

[billcopc]

I made a very simple live update system way back. It involved having all the latest files on a network share. Quite simply, every time the application was launched it would check that share for any files newer than its own and copy them over (thanks to a 30kbyte stub loader). Result: anyone who used my software was assured to have the latest version, and as a bonus if they were using it and it crashed, chances are they'd get a fix when they tried to reload it :)

I later used a variation on that scheme that involved a cron job on the server, checking regularly for new commits to the shared folder. It would then calculate windowed hashes of each file and the client update app would simply compare the server's hashes with its own (cached) hashes. This enabled me to minimize download times since it would only download the chunks that had been changed (in the case of large data heaps). It's not foolproof since I didn't do any insert/delete logic (add 1 byte to the beginning of the file and the rest is immediately invalidated)... but it was simple enough to justify the occasional forethought when releasing updates. It's like a castrated embedded version of rsync :) Damned easy to code too.

Considering the hell I've been thorugh with RTPatch and its ever-flaky software, it would be well worth writing my own smart binary diff (with proper shuffling detection and compression). These things really aren't that complicated to implement and the advantage of rolling your own is that you can include extra logic tailored for your application (or for that particular client).

Re:InstallShield

[engeeke]

I agree that InstallShield is a pretty good solution, but keep in mind that you've got to author your initial MSI properly or upgrades and patching will be very difficult. I've had to upgrade MSIs that weren't build properly initially (lots of "AllOtherFiles###" components, dynamically linked components, missing upgrade table, etc.), and if you don't build that first MSI properly then you're piling hacks on top of hacks. Spend a few bucks on a consultant or ask an expert for some free advice if you need to, but do it right the first time.

InstallShield offers an update service that helps automate the patch distribution, you might want to check out InstallShield Update Service for more information on the update service. It seems like a great option if you can't use BITS (and may be a good option even if you can).

(Hopefully links above don't violate terms of service, I did a quick scan and they don't seem to, but if they are in any way offensive I sincerly apologize. The point is to do it right the first time and get expert advice if you need it. InstallShield offers consulting too, and some of their team is pretty good.)