A high-level complete sequence diagram of BTE

[tokebe]

It would be very useful both for debugging and for new developers to have a high-level sequence diagram for BTE's query handling, either of the general sync endpoint or just starting from the query_graph_handler.

Optimally, this diagram would establish an explanation of the flow of data between each of the primary handler classes, grouped by file/module. Exact methods needn't be documented however the data structures/types (using the new vocab) moving between each handler should be annotated.

Making this diagram would entail stepping through the entirety of the lifecycle of a request, following all major data structures as they are created or obtained, and carefully organizing the diagram to display the module-handler hierarchy and how it interacts in the lifecycle of a request.

https://mermaid-js.github.io/mermaid/#/sequenceDiagram seems like a good tool to do this using markdown so it can be version controlled

[colleenXu]

feel free to move this around in the biothings project (I may not have put it in the right spot)

[tokebe]

Resolved by #491

[colleenXu]

Comments from 8/17 group meeting:

initial Feedback:

• make clear where the files are / when a module is being used
• Color? (issues with dark mode / browser extensions like darkreader?)
• It's awesome

Related sub-diagrams for specific behaviors:

• How we do the cron job, make MetaEdges (this is outside the scope of how-a-query-works workflow)
• How different modules work (call-apis, api-response-transform but this will be refactored??, biomedical-id-resolver)
• How caching works