Add processing execution link for traceability (#26)

* Add via link for traceability

* via to processing-execution

* example + changelog

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- `processing-execution` relation type to link to the processing execution that produced the data.
+
 ## [v1.1.0] - 2022-01-07
 
 ### Added

README.md

@@ -94,10 +94,11 @@ Potential expression formats with examples:
 The following types should be used as applicable `rel` types in the
 [Link Object](https://github.com/radiantearth/stac-spec/tree/master/item-spec/item-spec.md#link-object).
 
-| Type                  | Description                                                  |
-| --------------------- | ------------------------------------------------------------ |
-| derived_from          | URL to a STAC Item that was used as input data in the creation of this Item. |
-| processing-expression | A processing chain (or script) that describes how the data has been processed. |
+| Type                  | Description                                                                       |
+| --------------------- | --------------------------------------------------------------------------------- |
+| derived_from          | URL to a STAC Item that was used as input data in the creation of this Item.      |
+| processing-expression | A processing chain (or script) that describes how the data has been processed.    |
+| processing-execution  | URL to any resource representing the processing execution (e.g. OGC Process API). |
 
 ## Contributing
 

examples/item.json

@@ -35,7 +35,14 @@
       "Sentinel-1 IPF": "002.71"
     }
   },
-  "links": [],
+  "links": [
+    {
+      "title": "GRD Post Processing (90AF)",
+      "rel": "processing-execution",
+      "href": "https://api.example.com/processing/s1-grd-l1c/jobs/90AF",
+      "type": "application/json"
+    }
+  ],
   "assets": {
     "manifest": {
       "type": "text/xml",