CBRAIN is a collaborative, web-enabled grid platform built to facilitate research on large, distributed datasets by managing user access, transfer, caching and provenence for distributed data, as well as mediating interactions with high-performance computing centres (HPCs).
NeuroHub is an alternative interface to CBRAIN. It provides a few special capabilities that are not accessible in CBRAIN, while also lacking many of CBRAIN's features (because it is fairly new, as of August 2020). Users can switch back and forth between the two interfaces, since they share the same authentication and database systems.
CBRAIN (and NeuroHub) consists of two Ruby on Rails Applications: BrainPortal and Bourreau
BrainPortal is the frontend of the CBRAIN architecture. It is a Rails application that provides a web-based graphical user interface to CBRAIN. Users can upload, tag and search their files. They can launch compute-intensive processing jobs on remote High-Performance Computing (HPC) sites. Remote file repositories can be created to provide files from any network-enabled system.
Bourreau is the backend of the CBRAIN architecture. It is a Rails application that is not meant to serve the user directly. It interacts with the CBRAIN Brainportal application using XML, acting as an intermediary between user requests through BrainPortal and the cluster management software running on High-Performance Computing sites. A Bourreau receives requests to launch a processing task, sets up the required working directories, runs the process and then sends information about any newly created files back to BrainPortal. A Bourreau can also be queried about the jobs that are currently running on the HPC where it resides.
CBRAIN is extensively documented in its Wiki.