== System Design


Engines:

Der Engines Ordner enthält Subfolder
für die jeweilige Engine unterteilt
in Logik, Structs unt Tests


Storage:

Momentan beschränken wir uns auf SQLite
über SQLX ohne ORM

#figure(
  image("../../assets/Design.svg", width: 80%),
  caption: [
    The acting components of rvault.
  ],
)



=== Problem Description

// + The API to implement e.g. has the concept of mount points (similar to how filesystems can be mounted on UNIX-like systems).
// 	Mount points can contain multiple slashes.
// 	For example `/v1/some/mount/point/data/some/path/secret` may consist of a mount point `some/mount/point` and further, following routes of the mapped secret engine. //TODO
// 	In this example, `/data` is related to the Key-Value engine and `/some/path/secret` specifies a path within the secret engine instance mounted at the mount point.
// 	This implies a significant problem:
// 	How to determinate what part of the URL displays a mount point, where it is not certan, what the postfix of the URL will be (this problem follows).

// + Another problem is that based on the mount point, the request must be processed by the applicable secret engine.
// 	Based on context, stored on the DBMS, the request must be passed to the secret engine along with the determinated mount point.

=== Solution

// Secret Engines have their dedicated router.
// The main router has an instance of these routers along with the database pool wrapped within a struct in its state.
// The router instances have a reference to the database pool, which is internally wrapped by an Atomic Reference Counter (`Arc`).

// Upon a requst, the remaining path is obtained (via `/+mount_path`).
// Then, the path is looked up at the database, also requsting the engine type.
// If not found, the last last slash character and the following string is removed and looked up again. This is repeated, until the path either is found or has a length of zero, rejecting the request as "404 Not Found".

// If found, the router is called with the request and mount path is given to the router as an "Extension".
// The `call` #link("https://docs.rs/tower/0.4.13/tower/trait.Service.html#tymethod.call")[(link)]
// function which Axum routers inherit from the Tower crate, allows to hand the request over to engine's router.