Job Manager and Nodes

Owned by thomas (Unlicensed)
31 Jan, 2014
4 min read

Network simulations with RealFlow require two additional applications: the "Job Manager" and the "Job Node". Both programs can be downloaded from Next Limit's customer area on the RealFlow website.

The “Job Manager” is the main control centre and only needed once. During the adjustment of the network preferences you have already specified an IP address under “Manager Location” together with a port (65454 by default): the machine with this IP is the computer where the “Job Manager” must be installed. The “Job Node” application, on the other hand, must be installed on each computer you want to use for network simulations, but please keep in mind that you also need an appropriate number of licenses: 5 computers, for example, require 5 node licenses. 

Unpack and run the installers and follow the displayed steps. After a few seconds the programs should already be available. Before you can use them, a few adjustments and settings must be made. The programs can be identified and launched through their icons:

 

 

Both programs, the “Job Manager” and the “Job Node(s)”, must be configured to make them available in your network. You have to repeat this process for each “Job Node”, while the “Job Manager” settings are only made once.

Job Manager Configuration

This application can be installed on any computer of your network and the machine that holds the “Job Manager” can also serve as a simulation node. It is also possible to install an unlimited number of “Job Managers”, but please make sure that there is only one manager running per machine. The “Job Manager” application should also be visible to all computers in the network that are used for a distributed simulation.

The “Job Manager” can be launched with a double-click on the icon. A window appears and you are ready to make your settings. From the menu choose “Settings” (Windows/Linux) or “Preferences” (OS X) and – if necessary – change the default values. These settings are based on the values you have already specified in RealFlow's “Preferences” panel.

 

 

Here we are going to use the default settings:

Port Range

65454 is the communication channel between manager and nodes

HTTP Port

The web interface uses port 8080.

Maximum number of nodes connected

This value can remain untouched, except when you want to add more “Job Nodes”.

 

That is all you have to do, but it is necessary to restart the “Job Manager” to activate the settings. After the restart, the “Job Manager” should display some messages:

 

 

You can now open your browser or the “Job Manager” window in RealFlow's GUI application:

Layout > Job Manager

Go to the address line and type:

http://localhost:8080

Alternatively you can also enter the IP address you have specified in RealFlow's “Preferences” under “Manager Location”. In our example the address is 192.168.1.15:

http://192.168.1.15:8080

As you can see from the “localhost” address, “License Manager” and “Job Manager” are using exactly the same address, but different ports (2226/8080). This is the reason why they can share an IP (here: 192.168.1.15).

Job Node Configuration

To say it again: “Job Nodes” must be installed separately on each computer that you want to add to your network, but they can only be used if you hold an appropriate number of “Node” licenses. It is not possible to run more than one “Job Node” application per computer. If you are trying to start another instance you will receive an error.

The installation and configuration process is the same as with the “Job Manager” and, once again, you can find the parameters under “Settings” (Windows/Linux) and “Preferences” (OS X). There, enter the manager and the HTTP port to establish a communication. If you are using the default values you should immediately see a couple of messages telling you that “Job Manager” and “Job Node” are linked.

When you return to your browser and update the page you will also recognize the new “Job Node” in the “Nodes” table of the interface together with some information, e.g. the node's own IP address, the operating system and (this is important) the RealFlow version: the RealFlow versions of all connected nodes must match (or at least be of a version higher than the RealFlow GUI version that is used to send the jobs to the “Job Manager”), because nodes with different versions cannot be used for a network simulation. If you detect version conflicts we recommend to update your RealFlow applications.

 

 

Please also be aware that, if you want to use a computer for network simulations, the “Job Node” program must be running on this particular machine. It is not enough to start the computer – the node program has to be launched as well.

If a “Job Node” fails to find the license during a simulation it is a good idea to login to this computer, open a web browser and open the “License Manager's” interface, e.g.:

http://192.168.1.15:2226

This is the test to see if the “License Manager” is working correctly. If you cannot reach the address then there is something wrong with your network setup, e.g. corrupted settings or a firewall that blocks the required port. If you can see the program's web interface, but your license is not listed then the manager application is working, but you have to try to reinstall the license.