APIs provide a way for two systems to have a conversation with each other. eHive APIs provide ways for 3rd party systems to read and optionally write information from and to the eHive servers. You can think of this as being a telephone line between eHive and other systems with a pre-agreed set of basic questions, commands and responses.
Data can be harvested (copied) by other applications using the Open Archives Initiative Protocol for Metadata Harvesting. This process only has access to public data.
Data can be accessed by other application using the eHive-specific application programming interface (API). This can access either public or private data. All access is encrypted over HTTPS. Access keys are granted to each application using the Outh2 protocol.
OAI-PMH responses are in Dublin Core XML format. eHive API responses are in eHive JSON format.