The CData QuickBooks Desktop Gateway can be used to read and write to QuickBooks in situations where direct COM access to QuickBooks is not available (e.g., ASP.NET, Java, or QuickBooks on a remote machine). Follow the procedure below to connect to QuickBooks for the first time through the Desktop Gateway:

1. If you have not already done so, download the CData QuickBooks Desktop Gateway from here and install it.
2. Open the company file you want to connect to in QuickBooks using an administrator account in single-user mode.

3. Open the CData QuickBooks Desktop Gateway from the system tray and add a user on the Users tab. Enter a User and Password and select the level of access in the Data Access menu.

   Note: The CData QuickBooks Desktop Gateway does not use the User and Password properties to access QuickBooks; the User and Password properties authenticate the user. Authentication to QuickBooks is handled by the ApplicationName property.

4. When you first connect, a dialog appears in QuickBooks prompting you to authorize the application. After authorizing, you can execute commands to QuickBooks. Specify the URL of the Desktop Gateway and the User and Password. By default, the Gateway connects to the currently open company file.
5. If you want to access QuickBooks when QuickBooks is not running, save the company file information for the user. The Desktop Gateway automatically opens QuickBooks in the background with the company file for that user.

NOTE: that if the QuickBooks UI is open, you can only connect to that company file. Additionally, the user permissions you specify for the Desktop Gateway must match the user permissions you used for QuickBooks. The Desktop Gateway installs as a service in the current user account.

How do I Connect to QuickBooks over SSL/TLS?

You can enable SSL/TLS on the Advanced tab.

You will also need to send your public key certificate to the connector. You can do so by setting the SSLServerCert property.