LazAutoUpdater

Lazarus Auto-Updater

SourceForge Project

• Project Page
• SVN HTTP Checkout

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Workflow

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

• App downloads a small 'version.xml' 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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Version.xml

The format is as follows:

<?xml version="1.0" encoding="utf-8"?>
<APPCONFIG>
  <ProgramInfo>
    <Version GUI="0.0.2" OtherModule="0.1.0"/>
  </ProgramInfo>
</APPCONFIG>

The code to create it:

uses XMLConf
Var XMLConfig1:TXMLConfig; 
begin
 XMLConfig1.Clear;
 XMLConfig1.RootName := 'APPCONFIG';
 XMLConfig1.Filename := 'version.xml';
 XMLConfig1.OpenKey('ProgramInfo/Version');
 XMLConfig1.SetValue('GUI', '0.0.2');
 XMLConfig1.SetValue('OtherModule', '0.1.0');
 XMLConfig1.CloseKey;
 XMLConfig1.Flush;
end;

The code to read it:

uses XMLConf
Var XMLConfig1 :TXMLConfig; 
    szAppVer :String;
    szOtherMouleVer :String;
begin
 XMLConfig1.Clear;
 XMLConfig1.RootName := 'APPCONFIG';
 XMLConfig1.Filename := 'version.xml';
 XMLConfig1.OpenKey('ProgramInfo/Version');
 szAppVer:= XMLConfig1.GetValue('GUI', '0.0.0'); // Default is '0.0.0'
 szOtherMouleVer:= XMLConfig1.GetValue('OtherModule', '0.0.0'); // Default is '0.0.0'
 XMLConfig1.CloseKey;

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Deploying an update

• In the SourceForge project Files section, make a folder called 'updates'
• Upload 'version.xml' 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
• 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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