# WIP: infotainer

![Test](https://github.com/joppich/infotainer/workflows/Rust/badge.svg)
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__Note__: At the moment, this project is intended for me to learn and implement stuff I'm interested in. It's not really of any practical use to anyone.

Infotainer contains building blocks for simple pubsub services based on actix/-web, cbor and websockets.

## Components
* __[websocket interface](src/websocket.rs)__: handles client-server interaction
* __[pubsub service](src/pubsub.rs)__: manages subscriptions and handles publication of client submissions
* __[datalog service](src/data_log.rs)__: maintains log indices for and handles filesystem interactions

The websocket interface is an actor whose handlers are largely built around the `ClientCommand` and `ServerResponse` types. 
`ClientCommand` consists of struct variants holding data sent from client to server. These are translated into actix `Message`s by the `WebSocketSession` actor.  
The `ServerResponse` type is used to wrap data sent from server to client and can contain `HashSet<Uuid>`, representing a subscriptions log index, `Publication`, representing data published by some client, or `DataLogEntry`, containing one or more `Publication`s previously submitted to the data log.  

The pubsub service actor handles the `SubmitCommand` and `ManageSubscription` messages. When data is submitted for publication, the actor looks up the addressed `Subscription`, generates a `Publication`, sends it, wrapped in a `DataLogPut` message, to the `DataLogger` and proceeds to distribute it to connected clients subscribed to the `Subscription`.  
`ManageSubscription` has two variants, `Add` and `Remove`, and is used by clients to un-/subscribe from/to `Subscriptions`.

`DatalogService` enables persisting the server state as well as published data. `DataLogPut` messages represent write requests for `SubscriptionMeta`, subscriber lists and `Publication`s. `DataLogFetch` messages are used to retrieve persisted data. Additionally, it maintains a log of subscriptions and their publications.

## Features

- [x] websocket interface/ client message types
- [x] Subscription/Subscription table
- [x] Broadcast-type subscriptions
- [ ] Queue-type subscriptions
- [x] Publication
- [x] publishing messages
- [x] session management
- [x] data log service
- [x] persisting/retrieval of publication data
- [ ] persisting/retrieval of subscription metadata
- [ ] recreating server state from persisted data

## Is it any good?
[yes](https://news.ycombinator.com/item?id=3067434)