added d a part of Datacite documentation

docs/data-provision/aggregation/datacite.md

@@ -1 +1,42 @@
-# Datacite
+# Datacite
+This section describes the aggregation workflow of Datacite and the mapping implemented for it.
+
+## Datacite datasource
+[Datacite](https://datacite.org/index.html) is a leading global non-profit organisation that provides persistent identifiers (DOIs) for research data and other research outputs. 
+
+## Datacite API
+The [DataCite REST API](https://support.datacite.org/docs/api)  allows users to retrieve, query, and browse DataCite DOI metadata records. In particular, it exposes a method for incremental harvesting new datacite records.
+
+```
+https://api.datacite.org/dois?page[cursor]=$CURSOR&page[size]=$NUMBER_OF_ITEM_PER_PAGE&query=updated:[$FROM_DATE_TIMESAMP TO $TO_DATE_TIMESAMP]
+```
+
+On this API Request, we introduce some variables:
+- **CURSOR**: The value of the cursor to iterate the pages
+- **NUMBER_OF_ITEM_PER_PAGE**: (max 1000) defines how many records we can download for each page.
+- **FROM_DATE_TIMESAMP, TO_DATE_TIMESAMP** interval timestamp of the updated record
+
+
+Each record contains two pieces of information needed for incremental harvesting:
+- **isActive**: tell if the record is deleted (isActive:false)
+- **updated**: timestamp of last update
+
+
+## Collection Workflow
+
+The collection workflow is responsible for aggregating new datacite records. Each record is stored on a table called Native Datacite Store with the following schema:
+- **DOI**: The DOI PID of the datacite record (It is a primary key)
+- **update_timestamp**: the last update date timestamp
+- **json**: the native record JSON
+
+During the collection workflow, we identify the most updated record date, and the collection phase downloads all new datacite records and update the existing one through the API using this date as **FROM_DATE_TIMESAMP** variable.
+
+
+## Datacite Mapping
+The table below describes the mapping from the XML baseline records to the OpenAIRE Graph dump format.
+
+
+| OpenAIRE Result field path         | Datacite record JSON path     | # Notes           |
+|------------------------------------|-------------------------------|-------------------|
+| `id`                               |  `\attributes\doi`|the identifier will be created by folloing the openaire PID generation policy |
+| `instance`<br>`instance.type`      | `\attributes\types\resourceType` `\attributes\types\resourceTypeGeneral` `attributes\types\schemaOrg` |   Use the vocabulary _dnet:publication_resource_  to find a synonym to one of these terms and get the `instance.type`. Using the **dnet:result_typologies** vocabulary to find the `instance.type` synonym we can get one of the main entity: <br> `publication` <br> `dataset` <br> `software` <br> `otherresearchproduct`    |