Deploy The Latest Thing
- Deploy the latest main on shard.homework.quest
- Try to log in and try new functionality to bump stuff to done.
Concepts: Statefullness, Cookies, Channels, LiveViews
Stateless protocol:
- HTTP 1.0 was stateless
- No way to tell if two requests were from the same user.
- Idea: Unique session ID in every link.
Cookies:
- HTTP 1.1 added cookies, which let sessions be maintained across requests.
- Mechanism: Server sends a “set-cookie” header, browser sends back a “cookie” header with the same content.
- This adds state in the browser.
Server-side statelessness:
- Web apps are typically written to be stateless on the server, except for a database.
- That allows requests to be handled by separate processes or threads without worrying about locks / shared memory.
- A request spawns a new handling thread, the thread processes that request sequentially, then the thread terminates after sending the response.
AJAX / fetch:
- JavaScript in the browser can send HTTP requests without triggering a page reload.
- This is very powerful combined with in-brower rendering and partial page updates like with React.
- Problem: The server can’t send a response without getting a request.
Channels:
- Websockets allow for a persistent, bidirectional connection between a browser and the server.
- This requires some longer-term server state.
- Phoenix Channels handle this nicely (demo).
LiveViews:
- Run an elixir process on the server as long as a page is open in the browser, hooked up by a channel.
- Send events to the server, do partial re-renders server side, send diffs to the browser.
- This is obviously a bad idea, but internet connections are frequently so fast and reliable that it works great.
