Architecture

notes on architecture

Session is a Datastructure

A Datomic database, built up by the Session UI or other processes.

Defined by a Datomic schema

Purpose: convey sequences of computations

record sequence of computations (request and result pairs)

store the location of values, so that user code doesn't need to think/talk about places

allow for annotation of computations, via user and ecosystem-defined schema attributes

provide transaction stream for services to listen and react to

services speak to session via transactions, but can be or do anything (storage, hadoop, queues, etc)

Services interact via the Session datastructure

UI transacts a request, evaluator listens to transaction stream to detect it and take action.

Evaluator transacts a result, UI finds it in the tx stream and pushes it into the UI

Don't store large data directly

Instead coordinate the evaluator service with the storage service. (work in progress)

UI is simple wrapper of the Session datastructure

Represent UI elements as edn data

User-created content and session UI made of the "same stuff"

Perceive session and user content without relying on reproducing/reinitializing state

Stateless, as much as possible

Stateful UI can store its own state in datomic, with its own attributes

UI should reflect the current state of database

modulo new user input which waiting to be transacted

stream transactions into UI and update display as needed

because we have history, can recover previous version of session