Jim leads a deep dive into HTTP — how it works, why it's still the backbone of the internet, and what's changed since Tim Berners-Lee built it at CERN in 1991. Wolf and Jim cover the protocol from request methods to modern performance upgrades, with detours into cookies, CORS, WebSockets, and the tools they reach for when debugging.
Topics covered
- What HTTP is: Hypertext Transfer Protocol, created by Tim Berners-Lee at CERN in 1991; a text-based request/response protocol that underlies the modern web and REST APIs.
- Request methods: GET, HEAD, POST, and friends — including the newer QUERY method (published mid-2026) — plus what idempotency means and why it matters.
- Headers: Host, User-Agent, Content-Type, Content-Length, cookies, and the Accept header's role in content negotiation.
- Status codes: the 2xx/3xx/4xx/5xx mental model, the difference between 301 and 302 redirects, and a couple of joke codes (418 I'm a Teapot, 451 Unavailable for Legal Reasons).
- HTTP versions: from 0.9 (1991, no headers) through 1.0, 1.1 (reusable connections), HTTP/2 (2015, header compression, ~71% adoption), and HTTP/3 (2022, QUIC over UDP instead of TCP — now on roughly 40% of sites).
- Cookies: how they enable state in a stateless protocol, session-based login, and the tracking side of things.
- CORS: what Cross-Origin Resource Sharing is, why it's painful, and Jim's approach of funneling everything through a single HAProxy front end to sidestep it.
- WebSockets: how Jim's team uses them for real-time resource locking and push notifications in their scheduling system.
- Tools: curl (including the handy `-L` and `-O` flags), Postman, VS Code's OpenAPI plugin, HTTPie, and TCPdump/Wireshark for packet-level debugging (including decrypting HTTPS traffic with browser-exported keys).
Also in this episode
- Catching up on Jim's early-morning bike rides at Kensington Metro Park, and a reminder to wave at fellow trail users.
- Listener feedback from Marlon (writing testable code) and DaveMQ (mocking in tests, and a callout for Wolf's missing Mastodon announcements).
- A recommendation of Jonathan Livingston Seagull as a favorite philosophy read.
- A shoutout to Julia Evans (Wizard Zines) for her HTTP zine.
Links:
- Julia Evans Wizard Zine: https://wizardzines.com/comics/status-codes/
- 418 - I'm a Teapot: https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Status/418
Hosts:
Jim McQuillan can be reached at jam@RuntimeArguments.fm
Wolf can be reached at wolf@RuntimeArguments.fm
Follow us on Mastodon: @RuntimeArguments@hachyderm.io
If you have feedback for us, please send it to feedback@RuntimeArguments.fm
Checkout our webpage at http://RuntimeArguments.fm
Theme music:
Dawn by nuer self, from the album Digital Sky
