LazAutoUpdater

Lazarus Auto-Updater

Summary

• LazAutoUpdater is a visual drop-in component for the Lazarus/FPC IDE to make updating your application easier and simpler.
• It is aimed at Lazarus Windows developers who host their project in SourceForge.
• Drop-in the component, set one property (your sourceforge project name) and call these simple methods:
  • If LazAutoUpdate.NewVersionAvailable then...
  • LazAutoUpdate.DownloadNewVersion
  • LazAutoUpdate.UpdateToNewVersion

..and in your form.activate code:

• • LazAutoUpdate.ShowWhatsNewIfAvailable
• You (the developer) have plenty of control over how the component behaves, yet it is simple to use.
• End-users see the updating process as simple and transparent

SourceForge Project

• Project Page
• SVN HTTP Checkout

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Workflow

(Technical explanation)

The Laz AutoUpdater workflow for updating a running application is as follows:

• App downloads a small 'version.ini' file from sourceforge with version info (it can do this at start-up)
• App compares with its own internal version
• If new version available
  • App deletes any contents of local /updates folder
  • App downloads then unzips it from Sourceforge into a local /updates folder
• App uses TAsyncProcess to start the console updater.exe, passing it the name of the file to be updated in the command line
• updater.exe copies a downloaded 'whatsnew.txt' into the App folder and enters Sleep for a few seconds
• Meanwhile App has entered loop checking whether a 'whatsnew.txt' file has been copied into it's directory
• App detects 'whatsnew.txt' and Closes. (in other words the TProcess has started successfully)
• Updater copies /updates/UpdatedApp to App directory.
• Updater uses TProcess to start the updated app
• On Form.Show, App displays 'whatsnew.txt' then deletes it

The User sees:

• Dialog: 'There's a new version of xxx available. Would you like to download it?' Yes/No
• If Yes clicked:
  • Download happens in the background (via a background thread) Optional 'download counter' is shown to indicate progress.
  • User is prevented from closing the app whilst the download is in progress (in Form.CloseQuery)
  • Dialog: 'The update is downloaded. Click OK to install it and restart xxx now' OK
  • User clicks OK
  • A console (DOS window in Windows) opens automatically and the Application closes. The console says 'Please wait updating xxx'
  • After a couple of seconds the console disappears, and the new version of the App starts
  • As soon as the main window is shown, a 'What's New' info box is shown with an OK button
  • User clicks OK button, and never sees the info again

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Versions.ini

The format is as follows:

LazAutoUpdate versions file

[versions]
GUI=0.0.2
Module=1.0.0.0

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Deploying an update

• In the SourceForge project Files section, make a folder called 'updates'
• Upload 'versions.ini' into it
• Upload the zip file containing your updated EXE and the file 'whatsnew.txt'

• The application installer (Inno Setup?) goes into your Files section as normal
  • The Users should only have to download the installer once. All the subsequent versions will go into the /updates folder as above

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In-Application Code

• Here's what a typical 'Check for Updates' handler would look like:

 if LazAutoUpdater.NewVersionAvailable then
 begin
   if MessageDlg(Application.Title, 'A new version of ' + Application.Title +
     ' is available.' + LineEnding + 'Would you like to download it?',
     mtConfirmation, [mbYes, mbNo], 0) = mrYes then
     if LazAutoUpdater.DownloadNewVersion then
       LazAutoUpdater.UpdateToNewVersion
     else
       MessageDlg(Application.Title,
         'Update cancelled', mtInformation, [mbOK], 0);
 end
 else
 begin
   MessageDlg(Application.Title,
     'Your current version is fully up-to-date',
     mtInformation,
     [mbOK], 0);
 end;

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Roadmap

• Wrap as much as possible into a single visual component that a developer can drop onto their form, and set properties ...Done
• Enable (Console) update.exe to deal with multiple files to update
• Enable (Console) update.exe to deal with updates to subdirectories of the application
• Write full documentation so that the process is as painless as possible for developers
• Make the LazAutoUpdate itself auto-updateable via SourceForge

...work-in-progress

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