The SpatioTemporal Asset Tasking (STAT) API defines a JSON-based web API to query for potential future data and place orders ("tasking") for potential future data from remote sensing data providers (satellite or airborne).
STAT takes much of the work done by the STAC community and applies the lessons learned to this specification. The major departure from STAC is the requirement for uncertainty in many of the STAT properties.For example, a user requesting a data capture can provide a range of dates when they would like to capture. Conversely, a data provider cannot be certain of cloud cover in the future and must return a range of cloud cover probabilities to a user.
The STAT specifications define several new entities: Products, Opportunities, and Orders. These are
derived from the SpatioTemporal Asset Catalog (STAC) specification.
Ideally, STAT requests to providers will be ultimately fulfilled via delivery of a STAC Item, so STAT aims to
align with STAC core and extensions.
The core STAT specification provides a structure and language to describe Products, Opportunities, and Orders. The process of interacting with a data provider is done through a REST API.
The core of STAT API includes the /products endpoint and the /orders endpoint.
To know which constraints are available for which product_id, users first explore /products. These constraints can be used to form a POST to the /orders endpoint.
The /opportunities endpoint provides additional functionality on top of core and is designed to be used
after /products and before /orders. It allows users more fine-grained
control and selection of available tasking opportunities by letting them explore the opportunities which
are available for a chosen order configuration. The opportunities are
represented in a FeatureCollection, with order specific attributes and values in the feature properties.
STAT APIs follow the modern web API practices of using HTTP Request Methods ("verbs") and
the Content-Type header to drive behavior on resources ("nouns") in the endpoints listed below.
The following table describes the service resources available in a STAT API implementation that supports all three of the foundation specifications. Note that the 'Endpoint' column is more of an example in some cases.
| Endpoint | Specified in | Returns | Description |
|---|---|---|---|
/ |
Core | ? | |
/products |
Core | ProductsCollection | Figure out which constraints are available for which product_id |
/orders |
Core | OrdersCollection | |
POST /orders |
Core | Order | Order a capture with a particular set of constraints |
/products/{productId} |
Core | Product | |
/opportunities |
Opportunities | OpportunitiesCollection | |
POST /opportunities |
Opportunities | Opportunity | Explore the opportunities available for a particular set of constraints |
STAT API utilizes OGC API Features Conformance JSON structure. For STAT API, we declare new STAT conformance classes, with the core ones detailed in the table below.
The core STAT conformance classes communicate the conformance JSON only in the root (/) document, while OGC API
requires they also live at the /conformance endpoint. STAT's conformance structure is detailed in the
core. Note all conformance URIs serve up a rendered HTML version of the corresponding OpenAPI document at the given location.
| Name | Specified in | Conformance URI | Description |
|---|---|---|---|
| STAT API - Core | Core | Specifies the STAT Landing page /, communicating conformance and available endpoints. |
|
| STAT API - Opportunities | Opportunities | Enables request of potential tasking opportunities |
The Landing Page will at least have the following conformsTo and links:
{
"stat_version": "0.1.0",
"id": "example-stat-api",
"title": "A simple STAT API Example",
"description": "This API demonstrated the landing page for a SpatioTemporal Asset Tasking API",
"conformsTo" : [
"https://stat-api.example.com/v0.1.0/core"
],
"links": [
{
"rel": "conformance",
"type": "application/json",
"href": "https://stat-api.example.com/conformance"
},
{
"rel": "service-desc",
"type": "application/vnd.oai.openapi+json;version=3.0",
"href": "https://stat-api.example.com/api"
},
{
"rel": "service-doc",
"type": "text/html",
"href": "https://stat-api.example.com/api.html"
},
]
}