Delphi: How do you auto-update your applications?

What ever scheme you use, it may be handy to know that you can actually rename a running .exe file. So rename file, copy in new file works nice. And the next time someone launch the program they will launch a the new version. This is ofcourse very handy in enviroment where many users run the same .exe file, like in citrix/terminal server/network share cases.

Years ago I wrote a simple tool which is started instead of the real program, checks for updates, loads and installs them (if any are available), and finally starts the real application.

There are however problems with that approach if your program works in a properly administered environment, where users normally don't have write access to the program directories. You can no longer simply update your own program in such environments. That's why a lot of programs these days come with their own updater tool, which can be installed to run with elevated permissions, so that program updates can be applied even though only standard users do ever log on to the system.

You have to decide whether your target audience can be assumed to run on power user or administrator accounts, or whether you will have to deal with above-mentioned problems. With Vista things got considerably harder already.

With all these problems (net access over proxies, missing write permissions for installation directories, the need to update files that the updater itself is using - just to name a few) I wouldn't try again to code this on my own. Much better to check if any one of the available solutions does all you need it to.

I use the Synapse routines GetHTTP to return a specific resource, and if found then check against the local system to see if an update is required. If so then the resource tells me what page to go to launch and I throw the URL into shell execute so the users preferred browser is displayed.

Most of the time the download is a setup program created by InnoSetup which updates the users system and database to the latest version. When a new "paid" upgrade is needed, I then send the user to a "purchase upgrade" form. My web resources are ASP pages, so I can redirect to a different resource based on the customers version number.

For the main application (our application has a server piece, and a client piece) I have a loader which will check the server to see if the version of the client file on the server is different than the version on the client...if so, it prompts the user if the user wants to update/revert. We chose to prompt the user as sometimes an accidental bug might make it into the system and the user has to downgrade/upgrade only specific machines to help troubleshoot. I maintain a database record with the minimum version required which is updated via the database patch, so if a version must be retired then the record is updated accordingly.

I created my own solution too based on Indy for downloading and http://sourceforge.net/projects/makeupdate/ for file patching. Before that I have used and tried several commercial tools, but no one was doing exactly what I needed.

I use TmxWebUpdate. It's free, simple and gives you good control over the process. I actually own TMS Component Pack with TWebUpdate but never really found a good reason to switch.

Edit: Link updated

Normally we use the third party tool. But in some situations it was not usable so I created an own solution, which was pretty standard:

• Get xml (or any other format) with update info.
• If newer files are published, download and install them.

I use TWebUpdate . It works ok and has a ton of interesting options, but documentation isn't so great and I did bump into a few problems - which is why I download a full installer, instead of just the files...

I will be keeping an eye on this question, btw...

Same as "stg" and "GuyWithDogs", I'm using TWebUpdate from TMS. Although the documentation isn't so great, Its not so difficult to learnt.

With TWebUpdate, you have some options what the protocol you use, it could be done via HTTP, FTP or network access.

For communication layer, TWebUpdate uses WinInet. In some machines, the windows / IE URL cache can be frustating, so I've added a routine to clear the auto-update server address from cache first to ensure the information gathered from the server is up-to-date.