Client Installation

Downloading the SimStack client

For Linux and Windows systems, the latest version of the SimStack client is available here. The client version installs itself and all dependencies during the first launch. After extracting the .tar.gz or .zip files from the downloaded archive, move it to your local filesystem, and run the proper commands according to your operating system.

The client version requires passwordless via ssh access to communicate with the HPC. If you do not have passwordless via ssh access to the HPC resources already preconfigured, you need to generate a ssh keypair and transfer it to your authorized_keys file of your user account on the available HPC resource. You achieve this with two simple commands, as shown below.


Please run the below commands on the same local machine, where the SimStack client will be installed.

Installation on Linux

If you don’t have the ssh keys, use the steps below to generate them.

  • ssh key generation, just press enter for the passphrase option.

    ssh-keygen -t rsa
  • The ssh-key command above generated two keys in the ~/.ssh directory. Now you have to copy the key to your user account in one of the available HPC resources.

  • Please choose the HPC where you want to have passwordless access.

  • Test the connectivity of your passwordless ssh by running one of the commands below in the Powershell prompt.

  • After completing, the above steps runs the below commands.

    cd  simstack_linux

Installation on Windows

If you don’t have the ssh keys, use the steps below to generate them.

  • Make sure that the ssh is enabled on your Windows system.

  • Check if Powershell is installed on your Windows system, if not you can install it from the Microsoft Store.

  • To generate a public/private rsa key pair on Windows, open the Powershell prompt run the below command, and just press enter for the passphrase option.

  • To copy the ssh key to your user account on the HPC resource, choose and run one of the commands below in the Powershell prompt. Literally copy the command changing only the user.

    type $env:USERPROFILE\.ssh\ | ssh "cat >> .ssh/authorized_keys"
    type $env:USERPROFILE\.ssh\ | ssh "cat >> .ssh/authorized_keys"
  • After completing, the above steps, double click on run-simstack and be happy.

Testing the connectivity

You can test the connectivity of your passwordless ssh in both systems by running one of the commands below. You successfully transferred the key if you establish the ssh connectivity to your HPC without entering your user password.



The HPC resource considered here for this tutorial are the int-nano (first line) and bionano (second line) clusters. Please note that you must replace the user with your user account characters in the above lines, and here we are considering that you named your public ssh key as located in the .ssh\ directory. This website has a detailed explanation of how to generate ssh keys on Windows and copy it to your HPC resource.

Simstack Server Configuration

  • Setup the server by opening the configuration menu: Configuration -> Servers


You must replace the characters xxxxxx with your proper setup as highlighted in the figure above, and don’t forget to load (SSH Private Key) your ssh key.

  • Registry Name: accepts any name.

  • Base URI: can accepts any HPC IP, but here we will limit ourselves with one of the below options.



  • Username: enter with the user account according to your available HPC resource.

  • If ssh key is setup correctly, you should now be able to connect by clicking the Connect button at the top right of SimStack. The green button means you successfully connect to the server.



If you get an error message during your try, double-check the field on the server setup.

Simstack Overview


SimStack’s basic graphical user interface elements.

Using the SimStack client (picture above), simulation workflows are constructed by dragging and dropping various (already incorporated modules) from the window on the left side area (Available WaNos) into the Workflow canvas area. Double click each module to modify module-specific parameters (see input file field) and allocate resources in the Requested computational resources field for each module. To save and reuse your workflow lately, press ` Crtl+S` or `File -> Save`. It will then appear in the left panel Saved Workflows and can be re-loaded by double-clicking. To submit your workflow, connect to the computational resource (the connect button as shown in the last figure of Simstack Server Configuration section) and click `Run -> Run` on the menu bar, or `Crtl + r`. All required input files are uploaded automatically to the HPC resource, and workflow modules may run serially or in parallel, depending on if your workflow uses or not some of the Loop controls features. As shown in the figure above, the SimStack client will display a yellow folder while be running. When successfully finished, the client will exhibit a green folder, and you will be able to retrieve all the relevant data from your simulations. If the simulation presents a computational issue during the execution, SimStack returns a red folder, which we can be inspected to fix the problem.