architecture.md

Architecture

What follows is some light documentation on how stac-map is built.

Core concepts

Here's the two core concepts of stac-map.

Everything starts with the href

stac-map is driven by one (and only one) href value, which is a URI to a remote file or the name of an uploaded file. The href is stored in the app state and is synchronized with a URL parameter, which allows the sharing of links to stac-map pointed at a specific STAC value.

The value could be (almost) anything

Once the href is set, the data at the href is loaded into the app as a single value. The value could be:

• A STAC Catalog, Collection, or Item
• A STAC API
• A GeoJSON FeatureCollection with STAC Items as its features (commonly referred to as an ItemCollection, though no such term exists in the STAC specification)
• A stac-geoparquet file, which is treated as an ItemCollection.

The behaviors of the app are then driven by the attributes of the value.

Concept diagram

Any values that don't have a parent are set by the user, either directly (e.g. href) or by interacting with the app (e.g. bbox).

flowchart TD
    h[href] --> value;
    value --> catalogs;
    value --> collections;
    collections --> filteredCollections;
    bbox --> filteredCollections;
    datetimeBounds --> filteredCollections;
    value --> linkedItems;
    linkedItems -- if no user items --> items;
    search --> userItems;
    userItems --> items;
    items --> filteredItems;
    bbox --> filteredItems;
    datetimeBounds --> filteredItems;

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