xpra

Visualization Template

Template of a LEXIS workflow allowing to transfer a dataset from DDI to a Cloud Compute instance on which ParaView is accessible through a Xpra remote session:

The Run workflow is doing:

• the transfer of an input dataset from DDI to a Cloud Staging Area
• the allocation of a Cloud Compute instance
• the SSHFS mount of the staging area on this compute instance
• the copy of data on this cloud staging area locally on the compute instance
• the installation and run of Xpra remote display along with ParaView
• the cleanup of resources once the session has expired or was closed by the user

Input properties

The template expects the following input properties (mandatory inputs in bold):

• token: OpenID Connect access token
• project_id: LEXIS project identifier
• visualization_dataset_path_input_path: Dataset path in DDI containing visualization data
• visualization_walltime_minutes: Duration in minutes of the visualization session
• visualization_decrypt_input: Should the input dataset be decrypted (default: false)
• visualization_uncompress_input: Should the input dataset be uncompressed (default: false)
• visualization_directory: Directory where visualization data will be accesible on a cloud instance (default: visualization)
• visualization_mount_point: Directory where visualization data will be mounted from Cloud staging area (default: /mnt/visualization)
• visualization_ca_pem: PEM-encoded certificate authority content. Will be generated if not provided, but the user will get a warning that he attempts to connect to a server with an invalid certificate authority (as unknown certificate issuer)
• visualization_ca_key: Certificate authority private key content, will be generated if not provided
• visualization_ca_passphrase: Certificate authority private key passphrase
• visualization_port: Port to use to expose the remote display, should be > 1024 (default: 8080)

Ouput attribute

The following output attribute is provided:

• attribute url of component XpraJob: the URL of the remote visualization session

Access to the remote session

Once the XpraJob job is running, the remote session URL is available in the Application outputs in Alien4Cloud. Click on it and you will get an access to the remote session with Paraview running. Select File> Open in Paraview, and select the data to visualize in the home directory visualization (by default). Click on Apply in the Properties pane on the left hand side to visualize you data:

Ending the workflow

The remote display session will automatically be stopped atfer the duration provided in input property visualization_walltime_minutes is elapsed.

But the use can end the session himself clicking on the top left menu of Xpra and selecting Server > Shutdown Server and the workflow will then continue with a cleanup step to release the Cloud compute instance: