Hey everyone, Ryan here! Today, let’s talk about something that’s so fundamental to the web, we often take it for granted: HTTP/1.1. You might not hear much buzz about it these days, especially with its more modern sibling, HTTP/2, grabbing all the headlines, but HTTP/1.1 is the workhorse behind so much of our daily online activity, and its history is actually pretty fascinating!

Before the sleek performance of HTTP/2, we relied on good ol’ HTTP/1.1 to get us from point A to point B on the internet, and even still, HTTP/1.1 is hugely present today. Let’s dive in and see what makes it tick.

The Origins of Our Web Communication

HTTP, short for Hypertext Transfer Protocol, is what allows your web browser to communicate with a server. We’re talking the lingua franca of the web here! It started way back in the early days of the internet and went through various iterations until HTTP/1.1 came along and really established the fundamentals of modern web browsing as we know it. It’s pretty incredible to think about how it transformed the internet!

Key Features of HTTP/1.1

HTTP/1.1 is more than just some dry technical spec; it laid the foundation of how we access content online. Here are some of its core features that helped make the internet what it is today:

• Text-Based Protocol: Unlike the binary nature of HTTP/2, HTTP/1.1 relies on human-readable text messages to communicate between browsers and servers. While convenient for debugging, this approach isn’t always the most efficient when it comes to data transmission.
• Request/Response Model: At its heart, HTTP/1.1 is based on a straightforward request and response pattern. The client sends a request, and the server provides the requested data as a response. This basic model remains core to how most interactions work on the web, and will always be core in the future with things such as WebSockets and Server Side Events.
• Persistent Connections: One big improvement over its predecessor HTTP/1 (yes, there was one!) is the use of persistent (or keep-alive) connections. These reusable connections helped mitigate overhead associated with creating new connections for each request. This was a step up and saved significant resources, but has limitations!
• Methods (GET, POST, PUT, DELETE): HTTP/1.1 defined the request methods we’ve come to know. GET to retrieve data, POST to send data, and so on. These methods gave us a structured way to interact with servers which can have REST API endpoints.
• Headers: Sending Context: These add useful info, allowing for a lot of versatility for any type of web data transfer. Headers such as Accept: ”/”, Cookie, Host etc., would tell the browser how the user intended to access content.

Limitations and the Need for Improvement

While HTTP/1.1 was (and still is) an incredibly successful technology, it does have some performance limitations which became more apparent over time as websites grew more complex. Here’s the rub:

• Head-of-Line Blocking: This is where things get a bit tricky. Although HTTP/1.1 can handle multiple requests on a persistent connection, they are all handled one at a time and sequentially, and if one file in that sequence takes a while, everything else needs to wait. Imagine waiting for someone’s super long order to finish to finally get a basic drink you asked for (that analogy again, haha).
• Header Repetition: You can end up sending the same data over and over. Think about your user agent, and which content types you’ll support, and every single request needs those. HTTP/1.1 sent full header data on each request/response which led to bandwidth wastage.
• TCP Connection Overhead: HTTP/1.1, browsers often need to make multiple connections to servers, causing delays during the TCP connection phase as these connections are resource intensive.
• Server Pushing not an option Although it’s easy to make a server “respond” with a list of files (via HTML), it is not easy to proactively push assets, something that would allow for performance improvements in how a server renders your page for the visitor

What Does an HTTP/1.1 Request Look Like?

Okay, here’s where it’s nice and clear: unlike the binary magic of HTTP/2, an HTTP/1.1 request is text-based, so we can just look at it! It would look something like this:

GET /index.html HTTP/1.1
Host: www.example.com
User-Agent: MyBrowser
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Connection: keep-alive

Simple, right? You’ve got a request method (GET), a path, and various headers that give all sorts of context for your server. And every request on an active HTTP/1.1 connection could look very much similar with slightly different content.

The Legacy of HTTP/1.1 Despite being superseded by its faster sibling HTTP/2, HTTP/1.1 still forms a large backbone of the internet, because it can act as a backup for modern connections when HTTP/2 negotiations are unsuccessful, such as due to network intermediaries such as CDNs or proxies. This means there is great value in understanding how to get it right, with efficient cache, minified assets and resource delivery, especially if your app has older network infrastructure support needs.

Wrapping Up

So there you have it – a brief tour of HTTP/1.1! It’s a crucial protocol that continues to serve as the cornerstone of web communication. Its evolution is a testament to the constant innovation that continues to shape how we use the internet every day. And I personally think there is some nostalgia in revisiting how we made web development progress in such a crucial way over 20 years ago.

We’ve seen it’s strengths (text format, persistence) and limitations (blocking, header redundancy, tcp connection issues). So when I say we’ll be discussing a much more exciting successor, HTTP/2, very soon - you’ll understand exactly why that’s the next step up in delivering more content in a more effective way.

What are your thoughts on HTTP/1.1? Any memories or experiences? Let’s hear them in the comments below!