Launching Desktop Sessions¶

Desktop sessions provide a full Linux graphical environment in your browser, giving you access to traditional astronomy software with familiar desktop interfaces. This guide walks you through launching and using desktop sessions on the CANFAR Science Platform.

🎯 What You'll Learn

How to launch, connect, and size desktop sessions
What software is available and how to launch it
How to manage files and storage within desktop sessions
Tips for collaboration, performance, and troubleshooting

Overview¶

Desktop sessions offer:

Full Linux desktop: Complete graphical environment in your browser
Multi-application workflow: Run multiple programs simultaneously
Traditional interfaces: Use software with graphical user interfaces
File management: Visual file browser and management tools
Session persistence: Resume work exactly where you left off

Common use cases include:

Running GUI-based astronomy software (DS9, SAOImage, IRAF)
Complex multi-step workflows requiring multiple applications
Teaching and demonstration scenarios
Legacy software that requires a desktop environment

Creating a Desktop Session¶

Step 1: Select Session Type¶

From the Science Portal dashboard, click the plus sign (+) to create a new session, then select desktop as your session type.

Step 2: Choose Container¶

The desktop container includes a comprehensive set of astronomy software. Currently, there's one main desktop environment available with pre-installed tools.

Step 3: Configure Session¶

Session Name¶

Give your session a descriptive name that will help you identify it later (e.g., "data-reduction", "teaching-session", "multi-instrument-analysis").

Resource Configuration¶

Desktop sessions typically require more resources than other session types:

Memory (RAM): - 16GB (recommended): Standard desktop usage - 32GB: Multiple applications or large datasets - 64GB: Intensive workflows with large data

CPU Cores: - 2 cores: Basic desktop operations - 4 cores (recommended): Multiple applications - 8+ cores: Compute-intensive desktop workflows

Step 4: Launch Session¶

Click the Launch button and wait for your session to initialize. Desktop sessions may take slightly longer to start than other session types.

Your session will appear on the Science Portal dashboard. Click the desktop icon to access your session.

Connection Timing

Sometimes it takes a few seconds for the session link to work properly. If you see a "Bad gateway" error, wait a moment and try again.

Connecting to Your Desktop¶

Initial Connection¶

Click the Connect button to access your desktop environment.

Desktop Environment¶

You'll see a full Linux desktop environment with:

Taskbar: Application launcher and system controls
File manager: Browse your storage and files
Terminal: Command-line access
Pre-installed software: Astronomy applications ready to use

Session Persistence¶

When your session becomes inactive, you'll be returned to the connection page. Click Connect again to resume exactly where you left off - all your applications and work remain open.

Available Software¶

Astronomy Applications¶

Your desktop session includes:

DS9: Advanced FITS image viewer and analyzer
SAOImage: Astronomical image display
CASA: Complete radio astronomy suite with GUI
Python environments: With Jupyter, AstroPy, and other libraries
IRAF/PyRAF: Legacy optical astronomy reduction (if needed)

Development Tools¶

Text editors: gedit, vim, emacs
IDEs: Available through package installation
Version control: Git and other VCS tools
Compilers: GCC, Python, and other development tools

System Tools¶

File manager: Graphical file operations
Terminal: Full shell access
System monitor: Resource usage monitoring
Network tools: File transfer and connectivity utilities

Working with Applications¶

Launching Applications¶

Method 1: Application Menu 1. Click the applications menu in the taskbar 2. Browse categories (Graphics, Science, Development) 3. Click to launch your chosen application

Method 2: Terminal

# Launch DS9
ds9 &

# Launch CASA with GUI
casa --gui &

# Launch Python with astronomy libraries
ipython --pylab

Method 3: File Association - Double-click FITS files to open in DS9 - Right-click files for "Open with" options

Example: Multi-Application Workflow¶

Here's a typical desktop workflow for optical astronomy:

File Management: Use file manager to organize data
Image Display: Open FITS files in DS9 for inspection
Analysis: Launch Python/Jupyter for data analysis
Documentation: Use text editor for notes and scripts
Results: Save plots and analysis outputs

CASA Desktop Usage¶

To use CASA with its graphical interface:

# Launch CASA with GUI
casa --gui

# Or use the interactive shell
casa

The desktop environment allows you to use CASA's plotting and visualization tools that aren't available in command-line mode.

Desktop Session Tips¶

Copy & Paste Between Containers¶

Since different containers (e.g., CASA and terminal windows) in a desktop session may run on different remote computers, copying and pasting text between containers requires using the Clipboard application.

Accessing the Clipboard¶

Open the Clipboard: Click the arrow at the far left of the desktop to open the application menu
Find Clipboard: Look for "Clipboard" in the middle of the application list and click it

Using the Clipboard¶

The Clipboard serves as an intermediary for transferring text between containers:

Copy text: Highlight text in the source container and use Ctrl+Shift+C
Transfer via Clipboard: The text should appear in the Clipboard application
Select in Clipboard: Highlight the text in the Clipboard and press Ctrl+Shift+C
Paste to target: Click in the destination container and use Ctrl+Shift+V

Keyboard Shortcuts

Copy: Ctrl+Shift+C
Paste: Ctrl+Shift+V
These shortcuts work consistently across all desktop containers

Adjusting Font Size¶

Desktop containers support adjustable font sizes for better readability:

Changing Terminal Font Size¶

Access font menu: Hold Ctrl and right-click anywhere in a terminal window
Select size: Choose from the available font size options (Small, Medium, Large)
Apply immediately: Font changes take effect instantly

This feature works in: - Terminal windows - CASA command-line interface - Text-based applications

Font Persistence

Font size changes apply only to the current session. You'll need to readjust when starting new sessions.

File Management¶

Storage Access¶

Your desktop session provides access to:

/arc/projects/[group]/: Shared project storage
/arc/home/[username]/: Personal persistent storage
/home/[username]/: Session-local home directory
/tmp/: Temporary scratch space

Persistence Reminder

Use /arc/projects/ or /arc/home/ for important files. The session-local home and /tmp/ are not guaranteed to persist after the session ends.

File Operations¶

Use the graphical file manager for:

Drag-and-drop: Move files between directories
Visual browsing: Preview images and data files
Batch operations: Select multiple files for operations
Permissions: Set file and directory permissions

Data Transfer¶

Transfer files to/from your desktop session:

Browser upload: Use Science Portal file manager
Command line: scp, rsync, wget
Cloud storage: Mount external storage systems
USB/local: Upload through browser interface

Session Management¶

Resource Monitoring¶

Monitor your session resources:

# Check memory usage
free -h

# Monitor CPU usage
htop

# Check disk space
df -h /arc /tmp

Performance Optimization¶

Close unused applications: Free up memory and CPU
Use virtual desktops: Organize workflows across multiple desktops
Monitor network: Large file transfers can affect responsiveness

Ending Sessions¶

To properly end your desktop session:

Save all work: Ensure data is saved to persistent storage
Close applications: Exit programs cleanly
Disconnect: Close the browser tab
Delete session: Use Science Portal to free resources

Collaboration Features¶

Share your desktop session with collaborators:

Access session sharing from Science Portal
Add collaborator usernames
Set permissions (view-only or full control)
Collaborators see your full desktop in real-time

Teaching and Demonstration¶

Desktop sessions are ideal for:

Live demonstrations: Show software usage to groups
Hands-on training: Students can follow along
Collaborative debugging: Work together on problems
Code review: Visual examination of code and results

Troubleshooting¶

Common Issues¶

Session won't connect - Wait 30 seconds and try again - Check browser compatibility (Chrome/Firefox recommended) - Disable browser extensions that might interfere

Poor performance - Check resource usage with htop - Close unnecessary applications - Consider increasing session memory

Applications won't start - Check for error messages in terminal - Verify sufficient memory available - Try launching from command line for error details

File access problems - Verify paths to /arc/projects/[group]/ - Check group permissions - Ensure files aren't locked by other processes

Browser Optimization¶

For best performance:

Use Chrome or Firefox: Best compatibility and performance
Close other tabs: Free up browser memory
Stable connection: Ensure reliable internet connection
Disable browser extensions: Remove potential conflicts

Getting Help¶

Support: Email support@canfar.net
Community: Join our Discord for desktop tips
Documentation: Check software-specific guides for DS9, CASA, etc.

Best Practices¶

Resource Management¶

Plan resource needs: Estimate memory for your workflow
Monitor usage: Check system resources regularly
Clean up: Remove temporary files when finished

Workflow Organization¶

Organize windows: Use multiple desktops for complex workflows
Save frequently: Desktop sessions can be terminated for maintenance
Document work: Keep notes on your analysis steps

Data Management¶

Use persistent storage: Save important work to /arc/
Organize files: Create clear directory structures
Backup results: Important outputs should be backed up

Next Steps¶

CASA Desktop Workflows: Advanced CASA usage
Radio Astronomy Guide: Desktop-based radio analysis workflows
Batch Processing: Scale up desktop workflows
Notebook Sessions: Alternative analysis environment

Last update: 2025-08-07
Created: 2025-08-07