Messaging protocol and pipeline

Messaging protocol

Python to JS

• JSON string with a list of GL commands.
• GL command name and arguments.
• Arguments are serialized. NumPy arrays are serialized in a special format (with shape, data type, base64-encoded data buffer).

JS to Python

• User events: mouse, keyboard...

Pipeline

• Python script with use('web') backend.
• All GL commands are recorded (lazy evaluation), e.g. in two lists:
  • init_commands
  • paint_commands (flushed as soon as they are sent to the browser)
• The script ends with "show()" which fires up a server.
• Then, one needs to run the browser. The page connects to the Python process through WebSockets.
• Upon initialization, Python sends the init_commands and paint_commands to the browser, which executes them. Also, paint_commands is flushed.
• Upon user interaction, JS sends user events to Python.
• Python processes the user events, and triggers the corresponding Vispy events. All paint_commands are recorded, and sent back to JS.