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Last Updated: 02nd December 2010 03:58:28 pm

A floating license model gives you an easy way to validate the end-user’s rights to use the software. However, floating licenses depend on a stable network connection between the client machine, on which the licensed software runs, and the license server, which delivers the license to the client.

If a machine is not connected to a network or the network has frequent failures, the most obvious solution is to use a node-locked license model instead of a floating license model. With node-locked licenses, the license file must be generated and copied onto the specific machine. The environment variable LMX_LICENSE_PATH must be set to allow the software to “see” the license. The XML license template file for a node-locked license has some restrictions, as described in the section “Application licensing strategies” in the LM-X Developers Manual.

If you decide to use network licensing with an unstable network connection or with applications that are crucial to keep running, you should consider two solutions that will help with the reliability of license checkout for end users: grace licensing and high availability licensing (HAL).

Grace licensing

Grace licensing allows users to continue using a license if the connection to the license server is lost. When the license server goes down, the grace license will be available on the client machine for the currently logged in user for a specified number of hours. In this way, the user can continue their work without interruption, and without any need to borrow a license or take any other action to keep using the application.

To provide grace licensing to your users, simply add the GRACE=“hours” setting to the XML license template file.

High availability licensing (HAL)

HAL is another important feature for applications that require high availability. Activating HAL introduces fault tolerance, because the licensed applications no longer depend on a single point of failure. HAL uses three license servers, each assigned a specific role. The first license server is the primary server and allows clients to both checkout and borrow licenses. The second license server can allow clients to checkout licenses only, in the event the first license server is down. The third license server denies all requests, but is required as part of the configuration to ensure high availability.

To enable HAL, you must use the HAL_SERVERS=”3” setting and all three servers must be specified in the LM-X security configuration file. In addition, you must encode all three HAL license server hostids into the same license, and issue end users a single license that works on all three HAL servers.

Note that HAL requires a stable network connection between the servers. Too many network problems will make the system unstable and license checkouts unreliable.

For further details on how to configure HAL, see the “HAL_SERVERS (redundant servers)” section of the LM-X Developers Manual.