System terms and components

Terms and meanings

Runtime

The playback application on the device. It loads configuration and content, plays campaigns and displays the application layer, including embedded websites.

Connector

The communication application on the device. It maintains the connection to the message balancer, passes messages between the server and playback application, and handles previews, reports and service commands.

Updater

The application that updates playback software. It checks available versions, downloads packages, switches the active file and restarts the corresponding service. This is separate from updating Ubuntu.

Message balancer

The communication service linking connected clients. In this system it carries control messages, previews, interactions and reports; the name alone does not imply a standby server or guaranteed high availability.

Portal and API

The portal manages accounts, permissions, devices and content definitions. Its API is the programming interface used by administration and other components for specific operations.

File service

Stores and supplies media files and application packages. A definition in the portal may reference a file, but is not the file itself.

Media conversion

Preparation of uploaded media for further use. The output and processing depend on the file type; guides in the Media section explain the details.

Reporting service

Receives and processes operational data and playback totals. A playback report, remote preview and physical screen inspection are different sources of information.

Interactive service

Links a session on a visitor’s phone to the relevant application and device. This does not give the visitor an administration account.

RSS service

The server component that retrieves configured sources for RSS content. It is separate from a website opened directly on the playback device.

JCEF / Chromium

JCEF (Java Chromium Embedded Framework). Chromium is the engine that processes websites. JCEF connects it to Runtime, which receives its rendered output and forwards visitor input.

Off-screen rendering

Rendering a website into frames for inclusion in the playback interface. It does not mean that JavaScript or networking is disabled, or that the website is fully isolated.

Kiosk

The public visitor interface, such as the application menu. It is not another standalone service alongside Runtime, Connector and Updater.

Application sandbox

An environment that restricts a program’s permissions and resources and separates it from its surroundings. Hidden browser controls, navigation restrictions and off-screen rendering do not by themselves establish a complete sandbox.

Local API

An interface through which applications on the device communicate. A request to localhost targets the same device, but the service may also listen on other interfaces. LAN accessibility also depends on the firewall.

Portal proxy / HAProxy

The entry service in front of the portal API. In the described deployment it terminates HTTPS and forwards requests to the internal service over HTTP.

Content layer

The presentation layer plays campaigns; the application layer provides interactive content. These are ways of using the screen, not a security boundary isolating applications.

Stable / beta channel

The choice of application versions offered for an update. Stable and beta are update channels; they do not themselves confirm a package signature or a successful start of the new version.

Wayland / X11

Ubuntu display environments through which applications work with graphics and input. The variant depends on the installation and hardware; it is not a system content layer.

Service container

An environment for running a server service and its dependencies. Several containers can share one host server, so separate containers do not imply independent physical servers.

Report queue

Storage for records awaiting further processing or transmission. It helps with intermittent connectivity, but does not itself guarantee that each record is delivered exactly once.

RPO / RTO

Recovery objectives: RPO expresses how much recent data loss is acceptable in time; RTO is the target time for restoring service. Specific values must be agreed; the existence of backups does not determine them.

Application package / latest.jar

A file containing a version of a playback application. Updater downloads a particular version and points the active latest.jar path to it. This is separate from a user application created under My applications.

Identity verification and permissions

Identity verification establishes who is connecting. Permission checks decide whether they may perform a particular operation on specific data or a device. Neither check encrypts transport by itself.