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FOLIO is a new open source, cloud hostable, app-store based library platform, designed to facilitate collaboration between disparate development teams.

This glossary defines some terms to assist developers. Some other relevant documents are: Acronyms, Glossary.

FOLIO Components


The FOLIO middleware and API gateway. Okapi serves as the foundation layer for managing FOLIO apps and services. For more information, see the Okapi Guide and Reference.


The FOLIO UI toolkit. The Stripes toolkit provides a means of building web applications that expose the functionality of underlying Okapi modules. For more information, see the Stripes Core GitHub repository.

Stripes entities

The document Stripes entities: packages, modules, apps and more is a summary of terms used in that context, e.g. component, package, module, app, plugin.

Platform, LSP Base, LSP Extended

The “FOLIO Platform” and the “FOLIO LSP Base” and the “FOLIO LSP Extended Apps” are defined.

FOLIO Technologies and Concepts

Terms A-F


Application programming interfaces (APIs) are well-defined interfaces through which interactions happen.

App Store

An online portal for obtaining and installing software. FOLIO is designed to support the installation of both free and commercial modules and applications through an App Store.


Amazon Web Services and the Amazon EC2 Container Service is a cloud-based application deployment platform from Amazon. FOLIO is designed to play well in the cloud.


Bibliographic Framework Initiative (BIBFRAME).


Contextual Query Language (CQL). It was previously known as Common Query Language, and that is not to be confused with the OGC language of the same name.

Some starting points are:

A CQL example:

(username=="ab*" or personal.firstName=="ab*" or personal.lastName=="ab*")
and active=="true" sortby personal.lastName personal.firstName barcode

For other relevant CQL examples see the first two items above, and the API docs, and the debug output for tests in each backend module.


The basic functions of persistent storage: Create, Read, Update, Delete (CRUD).


Docker is a platform for managing software containers. FOLIO is well-suited for deployment in a Docker environment.


Definition of Done (DoD).


Don’t repeat yourself (DRY).


ECMAScript is the formally standardised version JavaScript. The Stripes Toolkit is written in ES6, a modern variant that introduces several new facilities.


Electronic resource management (ERM).


Functional Requirements for Bibliographic Records (FRBR).

Terms G-M


Integrated Library System (ILS).


JavaScript Object Notation (JSON) is an open-standard format that uses human-readable text to transmit data objects consisting of lists, collections and attribute–value pairs.

JSON Schema

Vocabularies that define the format of JSON instances.


JSON Web Token is a JSON-based open standard for creating tokens that assert some number of claims. JWTs are authenticated and encrypted, and used by Okapi.


Library Services Platform (LSP).


MARC (Machine-Readable Cataloging) standards.


Markdown is a simple plain text formatting syntax, used for documentation throughout the FOLIO code.


MongoDB is an open source, schemaless document database.


A pattern for building loosely-coupled, highly available, modular applications. Each component of a microservices-based application is a self-contained service, which communicates with other components over the network using a lightweight protocol. The FOLIO LSP is built using a microservices architecture.


A pattern of software architecture in which a single instance of the software is designed to serve multiple tenants, with appropriate security provisions and data separation. FOLIO is designed from the ground up to operate in a multitenant environment.

Terms N-R


NISO Circulation Interchange Protocol (NCIP).


Node.js is a JavaScript runtime for deploying JavaScript code.


npm is the Node.js Node Package Manager - a mechanism for distributing packages of JavaScript code, used by Stripes.

Okapi gateway

See Okapi explained above.


The Open Library Environment is a community of academic and research libraries collaborating to build open source library management tools. OLE has joined the FOLIO community to help with the development of FOLIO.


PostgreSQL (often called “Postgres”) is an open source enterprise-level relational database.


Proof-of-concept (PoC)


RESTful API Modeling Language - a language for the definition of HTTP-based APIs. Okapi module APIs (including the API of Okapi itself) are defined in RAML files and JSON Schema files.


Resource Description and Access (RDA).


React is a JavaScript library for building user interfaces.


Redux is a state container for JavaScript. Stripes uses React and Redux for building stateful JavaScript web applications.


Representational State Transfer architectural style, and RESTful web services, enable interaction between systems using a well-known set of stateless operations and responses.


The RAML Module Builder (RMB) framework, is a special FOLIO module that abstracts much functionality and enables the developer to focus on implementing business functions.

Terms S-Z


Apache Solr.


FOLIO is a single-page application (SPA).


Search/Retrieve via URL (SRU). Version “SRU 2.0” is “searchRetrieve Version 1.0, OASIS Standard”.

Stripes toolkit

See Stripes and the various Stripes entities explained above.


Universally unique identifier, a 128-bit number, see UUID at Wikipedia and How to check for a valid UUID.


Vert.x is a toolkit for building scalable, reactive applications on the JVM. Vert.x is particularly suitable for developing applications using the microservices architectural pattern.


The Node.js module bundler, used to deploy Stripes modules.


A generic term for Web Services Application Programming Interface (see API above).


Yarn is a package manager for Node.js and JavaScript.


Z39.50 refers to ANSI/NISO standard Z39.50, and ISO standard 23950 “Information Retrieval (Z39.50): Application Service Definition and Protocol Specification”. The Library of Congress is the Z39.50 Maintenance Agency.