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3. The Hub & Spoke model

One of the notable differences between Anaconda and most other operating system installers is its non-linear nature, also known as the hub and spoke model.
The hub and spoke model of Anaconda has several advantages, including:
The diagram below shows the installer layout as well as possible interactions between hubs and spokes (screens):

Figure 1. Diagram of the hub and spoke model

In the diagram, screens 2-13 are called normal spokes, and screens 1 and 14 are standalone spokes. Standalone spokes are a type of screen which is a type of screen that should be used only in case it has to be visited before (or after) the following (or previous) standalone spoke or hub. This may be, for example, the Welcome screen at the beginning of the installation which prompts you to choose your language for the rest of the installation.


Screens mentioned in the rest of this section are screens from the installer's graphical interface (GUI).
Central points of the hub and spoke model are hubs. There are two hubs by default:
Each spoke has several predefined properties which are reflected on the hub. These are:
To make the user interface clearer, spokes are grouped together into categories. For example, the Localization category groups together spokes for keyboard layout selection, language support and time zone settings.
Each spoke contains UI controls which display and allow you to modify values from one or more sub-trees of the in-memory tree-like structure which was discussed in Section 2, “Architecture of Anaconda”. As Section 6, “Writing an Anaconda add-on” explains, the same applies to spokes provided by add-ons.