eXo Repository Service is a standard eXo service and is a registered IoC component, i.e. can be deployed in some eXo Containers (see Service configuration for details). The relationships between components are shown in the picture below:
eXo Container: some subclasses of org.exoplatform.container.ExoContainer (usually org.exoplatform.container.StandaloneContainer or org.exoplatform.container.PortalContainer) that holds a reference to Repository Service.
Repository Service: contains information about repositories. eXo JCR is able to manage many Repositories.
Repository: Implementation of javax.jcr.Repository. It holds references to one or more Workspace(s).
Workspace: Container of a single rooted tree of Items. (Note that here it is not exactly the same as javax.jcr.Workspace as it is not a per Session object).
Usual JCR application use case includes two initial steps:
Obtaining Repository object by getting Repository Service from the current eXo Container (eXo "native" way) or via JNDI lookup if eXo repository is bound to the naming context using (see Service configuration for details).
Creating javax.jcr.Session object that calls Repository.login(..).