DrugBank 6.0 was implemented using a newly updated version of Ruby on Rails (http://rubyonrails.org, version 6.1.0 running on Ruby 3.2) web framework incorporating a MariaDB SQL relational database (https://mariadb.com, version 10.4) and a Neo4j graph database (https://neo4j.com, version 3.5) to manage all drug data, including entity relationships, external references, descriptions, visualization specifications and chemical structures. DrugBank utilizes a modular monolithic architecture, in which various systems are isolated based on clear domain boundaries. The structured knowledge stored in both its relational and graph databases is dynamically extracted and rendered into web pages by DrugBank's HTML interface responder. Search functionality across the website and its application programming interfaces (APIs) is provided by a custom search mapping software powered by an Elasticsearch cluster (http://elastic.co, version 6.5). DrugBank services (website, chemical structure handling, APIs and data processing pipelines) are distributed and vertically scaled across a series of virtual servers (UpCloud, http://upcloud.com) equipped in total with 138 CPU cores, 9.6 TB of disk space, 600 GB of RAM and an additional 15 TB of storage space on an Amazon S3 storage facility.
