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An Omnis library to load prerequisite libraries and automatically update libraries under the user's application data folder
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An Omnis library to load prerequisite libraries and automatically update libraries under the user's application data folder


  • Omnis Studio 10.0 or later
  • macOS or Windows (though this may work on Linux without modification)

Pre-loading libraries

app_loader.lbs manages loading one or more prerequisite libraries before starting a final, primary library. This works by separating prerequisite libraries into a lib folder and leaving the final library in startup.

Prerequisite libraries will be launched with their Startup_Task enabled, but should not rely on any other library to be open. The primary library's Startup_Task should be responsible for loading the application.

The expected folder layout is:

├── lib
│   ├── prerequisite1.lbs
│   ├── prerequisite2.lbs
│   ├── prerequisite....lbs
│   └── prerequisiteN.lbs
└── startup
    ├── app_loader.lbs
    └── primary.lbs

Since Omnis loads libraries in alphabetical order, your primary library should be named to load after app_loader.lbs. If this is not doable, rename app_loader.lbs to run first by prefixing it with an underscore, i.e. _app_loader.lbs.

Updating libraries

app_loader.lbs will also ensure the libraries in the application data directory are the same version as those in the program data directory under firstruninstall/. This is accomplished by tracking a build number, which is a single incrementing integer denoting one or more libraries has been changed.

When launched, app_loader.lbs will compare the build_number.txt file in the program directory's firstuninstall/startup with build_number.txt in the application data's startup/. If these build numbers differ the files in firstruninstall/lib/ and firstruninstall/startup/ will be copied to the application data directory, overwriting existing files.

Extra files will not be removed.

Any error that occurs will be logged to the Omnis trace log, which will be opened upon receiving an error.

Live updates

If you have a system to download and update files in the program directory, you can programmatically trigger app_loader.lbs to shut down all libraries, update files in the application data directory with new ones, then restart the libraries. This provides a live update that never closes the Omnis runtime.

The flow would be:

  1. Download the updated file or files
  2. Copy the updated file or files to firstruninstall/ in the program directory (this may require administrative rights)
  3. Message app_loader.lbs to reload the libraries using this call:
Do $itasks.app_loader.$reloadLibrary($clib)

The reload message will trigger app_loader.lbs to:

  1. Shutdown the library triggering the reload
  2. Close all open libraries besides app_loader.lbs
  3. Update the libraries in the application data folder from firstruninstall/
  4. Start all libraries in lib/
  5. Start all libraries in startup/


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