How the Solver and Risk Solver Add-ins Work
For many years, users like you have defined and solved models in Excel workbooks stored on their local PCs, using the Solver add-in included in Microsoft Excel (which was developed by Frontline Systems). The Solver add-in is installed on your local PC. Your Excel workbook is opened from disk, and solved "in place" using your PC's own resources (processor and memory). Neither Microsoft nor Frontline Systems ever "sees" your Excel workbook, unless you provide it separately, for example in technical support.
Modern Excel, Google Sheets, and Frontline's new Solver and Risk Solver add-ins operate differently. Your Excel workbook is stored online, in an Office 365, OneDrive, SharePoint or Google Drive file. When you use the Solver or Risk Solver add-in to solve or run a simulation, the actual solution is computed by Frontline's RASON® Server, operating as a "cloud service" on Windows Azure. For this to happen, it's necessary to transfer a copy of your Excel workbook, over the Internet, from its online location to our RASON Server. Your model is solved using the RASON Server's resources (processor and memory). While this entire process is designed to be secure, you should be aware of it.
The Solver and Risk Solver add-ins for modern Excel are offered under the Office Store's standard End User License Agreement (EULA), which disclaims all warranties and excludes or limits remedies and damages to the maximum extent permitted by law, and specifies that you bear all risk of using these add-ins. Solver and Risk Solver add-ins for Google Sheets have a similar EULA and disclaimers.You should only use these add-ins if you are comfortable with the privacy implications of this process.
Protecting Your Privacy and Information Security
Because Office 365, SharePoint, OneDrive and Google protect your Excel workbooks and other data, before our RASON Server can access your workbook, you must give your permission. You will see a pop-up window in your browser, saying that Solver or Risk Solver wishes to read your workbook, with a button "Trust It." Only when you click this button will the workbook be transferred to the RASON Server, using a limited-lifetime, secure (OAuth 2.0) access token.
The actual transfer of your Excel workbook contents between online storage and your browser, and between the online storage and our RASON Server, is encrypted using the industry standard Transport Layer Security (TLS) protocol. Your workbook is held in temporary storage on Windows Azure, and is deleted immediately after use.
How it Works in More Detail
► When you insert the Solver or Risk Solver add-in into your workbook, only a "pointer" to a Web server (operated by Frontline Systems, also on Windows Azure) is stored.
► When you activate the Solver add-in or Risk Solver add-in, its code is downloaded from Frontline's Web server into your browser, where it runs and displays its task pane. As you define your model, cell selections and options are stored in properties, which will be saved when your Excel workbook is next saved to online storage.
► When you click the Solve or Simulate button, the add-in and its Web server interacts with the Azure Authentication Service and your online storage server to obtain an access token. To avoid prompting you every time you re-solve your model, the access token may be cached in memory for a limited time. The RASON Server uses the access token to retrieve your workbook from your server, via TLS.
► Your workbook is held temporarily in a disk-based queue by the RASON Server; when it is processed and the solution is found, all disk and memory-based copies of the workbook are deleted, and the results are returned to the Solver or Risk Solver add-in in your browser. If you save the results, they will be saved when the workbook is next saved to online storage.