This chapter describes the usage of the PROMOTIC system in virtual computers. What is a virtual computer? Usually it is a system where there are multiple (independent) instances of a operating systems running on a single server (hardware) that appear as independent hardware platforms (while this is physicaly still a single server).
Virtual computers then allow to separate individual systems/applications in order to prevent them from influencing each other and to protect the operating system of the physical computer (server) itself.
For this purpose, there are multiple virtualization tools available: for example Microsoft Virtual PC
by Oracle, or VMware
. Some of these tools must be installed on the host system (HOST
). In the visrtual PC environment, it is possible to install additional hosted operating systems (GUEST
Specificity of operating the PROMOTIC system in virtual environments
The PROMOTIC system is very often used for data acquisition from different subordinate systems connected to the computer via Ethernet or via the computer's serial port (RS232/485
). The running PROMOTIC application also usually needs HW Key
license for its operation. It it is necessary to understand that the GUEST
systems usually have limited access to the physical devices of the computer (network card, USB
ports) and therefore the access for example to serial or USB ports may be limited or denied.
The possibility to make these physical devices available for HOST
computer in the virtual environment is dependant on the virtualisation tool that is being used. Some tools cannot allow usage of USB and in such cases it is necessary to consider different ways of the PROMOTIC system licencing, for example the PmLicServer
If the USB HW Key or serial port are usable in the virtual computer, then it is necessary to understand that using these in the virtual computer means that this haedware will not be available for HOST
computer or even for another virtual computers running on the same physical computer. It means that the physical hardware can be dedicated only for a single computer (physical or virtual).
Possible solutions of licencing the running application on a virtual PC.
1) The HW Key is plugged into the host PC and enabled to the virtual computer. See above.
then based on the application type and the way the application is running it can be licenced as follows:
a) HW Key containing the license - for applications that are accessed by Web clients and that is launched after OS Windows starts or as service of OS Windows.
2) The HW Key is enabled to the virtual computer by USB/Ethernet converter. This is not a recommended solution due to higher risk of instability after longer period of time. The usage of such key is similar to the applications described above.
3) The HW Key is plugged into an independent computer that is accessible in the Ethernet
network and is running the PmLicServer license server
service. The advantage of such solution is the possibility to run the NetKey service on a cheap, low performance computer and can also be used to provide license to other running applications.
4) The last possible solution is the usage of SW Key with hardware check. This solution is not recommended and can cause serious problems. Such license stops its functionality if the configuration of the virtual PC software is changed or updated.