The license file default is /usr/local/flexlm/licenses/license.dat (or C:\FLEXLM\LICENSE.DAT for Windows and Windows NT systems, SYS$COMMON:[SYSMGR]flexlm.dat for VMS systems). This default can be overridden by the developer via calling lc_set_attr(), or by the end-user setting the environment variable LM_LICENSE_FILE (logical name LM_LICENSE_FILE on VMS) to the pathname of the file. If at all possible, Globetrotter Software recommends keeping the license file in the standard location and allowing the end-user to move it by setting the LM_LICENSE_FILE environment variable.

The end-user installs lmgrd and the vendor daemon. If no redundancy is required, then these daemons run on one server node. If the network has only a single file server which contains all user files, then there is no advantage in having redundant daemons. If redundancy is desired, then the daemon would be installed on three server nodes. FLEXlm supports three server nodes operating as a single “logical” server node on UNIX and Windows/NT systems.

Once the license file and the daemons are in place, all that is required is to start the daemon when the machine boots. The daemon can be most conveniently started in
/etc/rc.boot, /etc/rc.local, /etc/rc, /sbin/rc3.d or /etc/rc3.d, depending on the operating system.

For Windows NT systems, lmgrd can be installed as a system service and started automatically when the system boots.

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Note: FLEXlm does not require the use of privileged sockets, therefore any user can start the FLEXlm daemons.

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If the license file is in the standard location (or the end-user has LM_LICENSE_FILE set properly) FLEXlm use is transparent to the end-user once the administrator has started the FLEXlm daemons.

If all the end-user data is on a single file server, then there is no need for redundant servers, and Globetrotter Software recommends the use of a single server node for the FLEXlm daemons. If the end-user's data is split among two or more server nodes and work is still possible when one of these nodes goes down or off the network, then multiple server nodes can be employed. In all cases, an effort should be made to select stable systems as server nodes; in other words, do not pick systems that are frequently rebooted or shut down for one reason or another.

The major trade-off in the client configuration options is the decision to terminate the application or let it continue running when it loses its connection to the daemon, which can indicate attempted theft. This policy decision must be made by each application vendor; FLEXlm can adapt to the required strategy.

The parameters available to implement the required policy are:

To implement a lenient policy, the number of retries can be set high, and the result of retry failure can be the display of a warning message with further retries at fixed intervals.

If a stricter policy is required, then the number of retries can be set low, with a relatively short retry interval, and termination of the application can be enforced. Other alternatives could include: limiting the functionality (disable printing for example) or slowing the performance of the product.

In both cases, the time while FLEXlm is retrying to connect to a daemon could be used to save files and checkpoint the application. If checkpointing were done and no new daemon connection were possible at the end of the interval, the application would be ready to exit.

Other client trade-offs concern the location of the license file and the appropriate selection of licensable features. In general, Globetrotter Software recommends that you leave the license file location at /usr/local/flexlm/licenses/license.dat (or C:\FLEXLM\LICENSE.DAT for Windows and Windows NT systems, and SYS$MANGER:FLEXLM.DAT for VMS systems), and let the end-user override this path, if necessary, as described in Chapter 12, “End-User License Administration.”

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Note: Globetrotter Software recommends that you do not override the use of the LM_LICENSE_FILE environment variable within your code.

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The application program is a client of FLEXlm. The routines to manage licenses are all contained in the FLEXlm client library liblmgr.a (lmgr.dll for Windows or lmgr32.dll for Windows NT and Win32s).

The include file lm_client.h contains all the symbolic definitions required for most calls. lm_code.h contains the vendor's encryption seeds and FLEXlm vendor key values. lm_attr.h contains the definitions used in the lc_set_attr() and lc_get_attr() calls.

FLEXlm supports the Software License Working Group API. See “Software License Working Group” for more information.

FLEXlm supports License Service Application Programming Interface (LSAPI). See “LSAPI v1.1”.

The following is an example of an application with calls to FLEXlm. The essential macros and functions are: LM_CODE(), lc_init(), lc_checkout(), lc_checkin().

#include "lm_client.h"
#include "lm_code.h"
/*
 *	ENCRYPTION_CODE_n are made up by vendor
 *	VENDOR_KEYn are provided by Globetrotter Software
 */
LM_CODE(code, ENCRYPTION_CODE_1, ENCRYPTION_CODE_2,
			VENDOR_KEY1, VENDOR_KEY2, VENDOR_KEY3, 
			VENDOR_KEY4, VENDOR_KEY5);
LM_HANDLE *lm_job = (LM_HANDLE *)0; /* first arg to all lc_xxx calls */
	/*...*/
	rc = lc_init(lm_job, VENDOR_NAME, &code, &lm_job);
	if (rc)
	{
		lc_perror(lm_job, "FLEXlm initialization failed");
		exit(rc);
	}
/*
 *	Check out feature
 */
	rc = lc_checkout (lm_job, "myfeature", "1.0", 1, LM_CO_NOWAIT, 
					&code, LM_DUP_NONE);
	if (rc)
	{
		lc_perror(lm_job, "Checkout failed");
		exit(rc);
	}
/*
 *	Checkout succeeded. Actual application code here
 */
	/*...*/
/*	
 *	Done with "feature", check it back in.
 */
	lc_checkin(lm_job, feature, 0);
	/*...*/