Backend federation

[sebbacon]

The mechanism by which data from heterogenous patient-identifiable patient sources can be safely combined, analysed and discarded.

For example, it should be possible to write a study definition that uses TPP and EMIS patient data and ONS death data, where the framework handles:

• Identifying which backend can supply each column of data
• Routing requests to that backend
• Coordinating secret-sharing for hashing patient identifiers
• Coordinating upload of each component to a shared area
• Combining the data
• Making it available to later steps in the pipeline
• Deleting this data as early as possible (there is a tradeoff between caching data for iterative development, and only keeping it for as a long as is strictly necessary)

This system requires a trusted (cloud?) infrastructure for the combination and storage of temporary cohorts and the execution of pipeline actions against them.