Listener
The Listener is the executor on a device. It receives calls addressed to that device and runs programs in its available environment.
Section 04 / Devices
Devices
Run programs on a computer, server or robot.
A computer, server or robot can host execution. A Listener receives Extella calls and runs programs on the connected device.
Why it helps
One workflow can connect digital tools with physical actions. The available actions depend on the connected equipment and its handlers.
What it contains
Computers and servers
The map describes execution on Mac, Windows, servers and VPS machines. Choose a device for the task and the resources it needs.
Robots and hardware
Programs can interact with devices through suitable handlers. Extella Dev includes a public delivery robot simulation that illustrates the principle.
Your own infrastructure
The map includes an on-premises scenario for execution within your own infrastructure. Deployment and access must be adapted to the environment.
What was measured
Extella measurements, September and October 2026. Each number holds under the conditions given.
- No inbound port is needed on the device.
The listener polls the Extella service itself: every 5 seconds on a laptop, every second on a server.
- A call takes seconds.
A program that runs for microseconds returns its answer in about 7 to 8 seconds: a median of 8.0 seconds on a laptop and 6.9 seconds on a server over 30 calls (02.10.2026). The time goes to the queue and polling, not to execution.
- One edit reaches every device.
A changed expert reaches every device with one save. Nothing needs to be reinstalled.
- One language runs on different systems.
The same language with one handler worked on a MacBook with macOS and on Linux servers (01.10.2026). A new device is prepared first: the listener and the programs the handler needs are installed.
Articles and demos
DemoTen shipsTen programs run as separate processes on a Linux server, together or one by one; game 9 sends a voyage that goes on after the page is closed.What it shows: The device does the waiting: on the Linux server ten ships came back in 20.3 s together against 51.4 s one by one (06.11.2026), and a voyage in game 9 keeps going after the page is closed.DemoRobot townA delivery robot with town rules: a model writes a few lines, and the handler on a device checks every rule.What it shows: Safety rules live in the executor, not in the model: a small model writes a few lines, the handler explains each mistake in words, and with 2 model calls (755 tokens) the robot delivered 6 parcels of 6.DocumentationWhere a program runsBefore a run, a device needs a working listener, a suitable handler and the program's dependencies.ArticleWhat we are still testingIncluding the path from a motion program to a physical robot.What it shows: Where the boundary is: what is not ready yet and what exactly has not been checked.
Related articles and examples.