wasm accessing system config and other wasm apis

[amitu]

If a system eg lets-talk-system is configured via lets-talk system alias thing, it can define data eg lets-talk.dashboard-url, and wasm can access this via calling ft-sdk::system_var("lets-talk.dashboard-url") -> Result<serde_json::Value, SystemVarError>.

The request will be sent to host, and host will evaluate the FASTN.ftd, find the lets-talk alias and its corresponding provided-via, evaluate that document and extract the variable-name out of it.

App SDKs

Every app has to has a system, for storing configuration and if any app wants to access configuration of any other app it should import that app's sdk crate, which gives a type safe wrapper over ft-sdk::system_var.

These SDKs will be very minimal, only type definitions etc.

App SDKs can also wrap HTTP calls for APIs defined in by that app, eg auth app can expose login/create account etc APIs, and any app can call those APIs using the SDK, which will internally make one wasm call another wasm with type safe API.