processing.adoc

OAPI - Coverages Processing Extension

This extension allows sending a WCPS request to a server for server-side filtering, processing, and fusion, generally: analytics on a coverage server.

To this end, the Processing Extension adds query parameters to the server offering:

q={wcps-query}

where {wcps-query} is a syntactically and semantically correct WCPS query.

The output is a (possibly empty) list of coverages or scalars, depending on the query result type.

Example:

http://acme.com/oapi/collections?q=for $c in (ERA5-cube) return max( $c.temperature )

Note that the query parameter is operating on collection level as any number of coverages can be combined.

Example:

http://acme.com/oapi/collections?q=for $c in (ERA5-cube), $d in (DEM) return encode( $c.temperature > 20 and $d > 100, "image/png" )

Error conditions:

• The query must be syntactically and semantically correct wrt. the service addressed.

OAPI Definition (draft)

The following is a working OAPI definition file for the demonstration service available at http://54.93.148.198:8080/rasdaman. It executes the WCPS query for $c in (S2_NDVI_84) return encode($c[Lat(51.9:52.1), Long(-4.1:-3.9), ansi("2018-11-14")], "jpeg" ) on the server and returns an image result. This can be tested by pasting the contents of the text box below into the swagger editor.

{
  "openapi": "3.0.1",
  "info": {
    "title": "WCPS",
    "description": "This is a sample WCPS server.",
    "contact": {
      "email": "[email protected]"
    },
    "version": "1.0.0"
  },
  "externalDocs": {
    "description": "Find out more about WCPS",
    "url": "http://doc.rasdaman.org/05_geo-services-guide.html#wcps"
  },
  "servers": [
    {
      "url": "http://54.93.148.198:8080/rasdaman/"
    }
  ],
  "paths": {
    "/collections": {
      "get": {
        "parameters": [
          {
            "name": "q",
            "in": "query",
            "description": "WCPS query to be executed by the server",
            "required": false,
            "schema": {
              "type": "string"
            },
            "example": "for $c in (S2_NDVI_84) return encode($c[Lat(51.9:52.1), Long(-4.1:-3.9), ansi(\"2018-11-14\")], \"jpeg\")"
          }
        ],
        "responses": {
          "200": {
            "description": "successful operation",
            "content": {
              "image/jpeg": {
                "example": null
              },
              "application/json": {
                "example": null
              },
              "text/plain": {
                "schema": {
                  "type": "string",
                  "example": 42
                }
              },
              "application/xml": {
                "example": null
              },
              "application/netcdf": {
                "example": null
              },
              "image/tiff": {
                "example": null
              },
              "image/png": {
                "example": null
              },
              "image/jpeg2000": {
                "example": null
              }
            }
          },
          "400": {
            "description": "Invalid query",
            "content": {}
          }
        }
      }
    }
  }
}