FOLIO is built for the cloud, and containerization is used extensively in the community environments as well as live production environments. PostgreSQL is typically the relational storage backend. Kafka and ElasticSearch technologies play a critical role in the operation of the system. Many hosting providers leverage AWS, but others, including many self-hosted deployments do not.
Back end modules are generally written as Java applications that expose their functionality through Okapi, FOLIO’s API gateway. Web service endpoints in Okapi can be, roughly, divided into two parts: general module and tenant management APIs, and endpoints for accessing module-provided, business-logic specific interfaces, e.g. Patron management or Circulation. Recently modules have been created using a Spring framework we refer to as Spring-Way.