Java Advanced Usage

9min
Detecting Virtual Machines
In case your License is using the Prevent virtual machine feature, the Java SDK will try to detect a Virtual Machine (VM) by comparing common VM signatures in hardware components of a node (computer).
In case any of the mentioned components match a VM component signature and the feature is active, the License activation will fail!
If you come across a Virtual Machine that's not properly detected, please submit a ticket with information about the VM used so we can add it to the detector.
Virtual Machines Currently Detected Using the Java SDK
The detection process compares the hardware signatures of the current node (computer) against a list of the following known VM signatures:
bhyve
Docker Container
FreeBSD Jail
KVM
LXC
Lguest
Linux-VServer
Microsoft Hyper-V
OpenVZ
Parallels
Project ACRN
QEMU
QNX Hypervisor
VMware
Windows Virtual PC
Xen/Oracle
Virtual Iron
VirtualBox
Multiple Licenses on Same Device in LicenseClient
By default, the LicenseManager is used as a singleton - but if there is a need for multiple LicenseManagers, each with it's own configuration - you can use the LicenseManagerFactory to create additional managers or use the singleton like before.
Java

// creates a new LicenseManager object, there can be multiple ones using this method
LicenseManager multipleLicences = LicenseManagerFactory.createLicenseManager();

// uses the singleton variant, only 1 manager can be initialized using this method
LicesneManager singleton = LicenseManagerFactory.getLicenseManager();

// creates a new LicenseManager object, there can be multiple ones using this method
LicenseManager multipleLicences = LicenseManagerFactory.createLicenseManager();

// uses the singleton variant, only 1 manager can be initialized using this method
LicesneManager singleton = LicenseManagerFactory.getLicenseManager();
﻿
Custom License Storage in License Client
By default the license is stored on the local disk - encrypted when storing. The location of the license can be changed via the Configuration object. A custom LicenseRepository can also be implemented, see sample below:
Java

// another way to initialize the manager
// is to pass it an additional field which is
// your own implementation of the LicenseRepository interface
public class MyLicenseRepository implements LicenseRepository {
  	void save(License license) {
      	// save the license
    }
 	void delete() {
      	// delete the license 
    }
  	License load() {
		// load the license
    }
  	// add any additional methods you need
}

try {
	licenseManager.initialize(configuration, new MyLicenseRepository());
} catch (LicenseSpringException e) {
    log.error(e.getCause().getMessage());
}

// another way to initialize the manager
// is to pass it an additional field which is
// your own implementation of the LicenseRepository interface
public class MyLicenseRepository implements LicenseRepository {
  	void save(License license) {
      	// save the license
    }
 	void delete() {
      	// delete the license 
    }
  	License load() {
		// load the license
    }
  	// add any additional methods you need
}

try {
	licenseManager.initialize(configuration, new MyLicenseRepository());
} catch (LicenseSpringException e) {
    log.error(e.getCause().getMessage());
}
﻿
Implementing Your Own LicenseSpring using LicenseSpring Core
This is possible to do, where you get to reuse most of the DTOs and authorization that was built. Feel free to contact us, if you require help of implementing your own SDK, with the boilerplate and authorization layers already finished.
Forward Proxy
The Java License Client﻿, Floating Client﻿, Proxy Floating﻿ and Management SDK﻿ - all have support for setting up a forward proxy. Just set the proxyPort and proxyHost fields in any of the configurations to use a forward proxy for your application. You can set just the proxyPort field - this will automatically use "localhost" as the proxyHost.
There is also support for Basic Auth, by setting the proxyUser and proxyPass fields in any of the configurations.
Here is an example setup for the License Client module:
Java
LicenseSpringConfiguration configuration = LicenseSpringConfiguration.builder()
                        .apiKey("api_key")
                        .productCode("product_code")
                        .sharedKey("shared-key")
						.proxyHost("192.168.0.254")
                        .proxyPort(1337)
  						.proxyUser("SampleUser")
						.proxyPass("SamplePass")
                        .build();
LicenseSpringConfiguration configuration = LicenseSpringConfiguration.builder()
                        .apiKey("api_key")
                        .productCode("product_code")
                        .sharedKey("shared-key")
						.proxyHost("192.168.0.254")
                        .proxyPort(1337)
  						.proxyUser("SampleUser")
						.proxyPass("SamplePass")
                        .build();
﻿
Disable SSL
disableSsl() still uses ssl traffic, it just trusts all certificates
﻿
In rare cases, some clients using a forward proxy cannot verify the public certificate of LicenseSpring servers. For these cases, there is an option in the the License Client, Floating Client and Management SDK called disableSsl
Here is an example setup for the License Client module:
Java
LicenseSpringConfiguration configuration = LicenseSpringConfiguration.builder()
                        .apiKey("api_key")
                        .productCode("product_code")
                        .sharedKey("shared-key")
						.disableSsl(true)
                        .build();
LicenseSpringConfiguration configuration = LicenseSpringConfiguration.builder()
                        .apiKey("api_key")
                        .productCode("product_code")
                        .sharedKey("shared-key")
						.disableSsl(true)
                        .build();
﻿
Shutdown Scheduled Executors
License Client (LicenseManager), Floating Client (FloatingLicenseService) and Proxy Floating Client (ProxyFloatingService) have the method shutdownScheduler(), which calls shutdownNow() for their scheduled executors. The executors are used in making periodic checks (if it's enabled) and in some cases will leave threads running indefinitely - when no shutdown signal is received.
Offline mode toggle
LicenseManager has the option to dinamically trigger offline/online mode with the method setOfflineMode(boolean) - mentioned here: https://docs.licensespring.com/sdks/java/modules/license-client#NzxDY

For detecting if the user has access to internet: The connection type is "com.licensespring.model.exceptions.infrastructure.ConnectionException", with the message: "api.licensespring.com: nodename nor servname provided, or not known" or message "timeout" - depending if the internet was available at some point during app running ("timeout" message if internet was available at some point and later disabled)
Updated 18 Jan 2024
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