D4.2 OpenAIRE back-end and Invenio upgrade: specification and release plan

The D4.2 OpenAIRE back-end and Invenio upgrade: specification and release plan (M3-ongoing, R-wiki) deliverable includes a specification of the software and a release plan for upgrading OpenAIRE back-ends and Invenio according to the data model in D4.1. The deliverable is on-going and will be updated at M15 (before first BETA release of the service), M23 (before second BETA release of the service), and M27 (before production release of the service).