How does http/af compare to cohttp in performance?

http/af is designed to fix cohttp's scalability issues, with benchmarks showing significantly lower latency and higher throughput under load, as detailed in the README's performance chart and statistics from issue #328.

How to use http/af with the Lwt runtime?

Refer to the examples directory in the repository for Lwt-specific usage; it involves setting up the server with Lwt's IO functions, similar to the Async example but adapted for Lwt's concurrency model.

Is http/af production-ready for high-traffic applications?

Yes, its focus on performance, memory efficiency, and scalability makes it suitable for production, especially in OCaml-based backends handling high request volumes, though you'll need to implement additional features like monitoring.

Does http/af support HTTP/2 or WebSockets?

No, http/af is strictly HTTP/1.1-only; for HTTP/2 or WebSockets, you'd need to use other libraries or build on top, which may require extra integration effort.

What are the memory usage benchmarks for http/af?

The README highlights memory efficiency through minimized allocations, but specific detailed benchmarks aren't provided; you may need to run tests based on your use case, as it's optimized for low overhead under load.

Can http/af be used with other OCaml runtimes besides Async and Lwt?

Yes, its IO-agnostic design allows integration with any runtime that provides basic IO operations, though official examples only cover Async and Lwt, so customization might be needed.

Open-Awesome

httpaf

NOASSERTIONOCaml0.7.1

A high-performance, memory-efficient, and scalable HTTP/1.1 web server for OCaml, built with Angstrom and Faraday.

GitHub

537 stars42 forks0 contributors

What is httpaf?

http/af is a web server library for OCaml that implements HTTP/1.1 with a focus on high performance, memory efficiency, and scalability. It solves issues like poor scheduling and excessive allocation found in other OCaml HTTP servers by providing a portable, IO-agnostic state machine for parsing and serialization.

Target Audience

OCaml developers building high-throughput web services, backend systems, or applications requiring efficient HTTP handling, especially those using Async or Lwt runtimes.

Value Proposition

Developers choose http/af for its superior performance and scalability compared to alternatives like cohttp, its memory efficiency, and its portable design that decouples HTTP logic from IO, allowing flexible runtime integration.

Overview

A high performance, memory efficient, and scalable web server written in OCaml

Use Cases

Best For

Building high-performance web servers in OCaml
Handling high volumes of HTTP requests with low latency
Creating scalable backend services for Async or Lwt runtimes
Replacing cohttp in performance-critical applications
Developing portable HTTP/1.1 servers across different platforms
Implementing memory-efficient HTTP parsing and serialization

Not Ideal For

Projects requiring HTTP/2 or newer protocol support
Developers seeking a full-featured web framework with built-in routing and middleware
Teams unfamiliar with OCaml or its concurrency runtimes like Async/Lwt
Quick prototyping without deep system-level optimization needs

Pros & Cons

Pros

Superior Performance Scalability

Addresses cohttp's poor scheduling and allocation issues, with benchmark data showing flat latency histograms and high request throughput under load, as highlighted in the README comparison.

Memory Efficiency

Minimizes allocations and optimizes resource usage, making it suitable for sustained high-throughput applications without excessive memory overhead.

IO-Agnostic Portability

Decouples HTTP logic from IO mechanisms, allowing seamless integration with Async, Lwt, or other runtimes, as demonstrated in the provided examples.

Standards-Compliant Implementation

Implements HTTP/1.1 parsing, serialization, and pipelining as a portable state machine using robust libraries like Angstrom and Faraday, ensuring correctness.

Cons

Limited to HTTP/1.1

Does not support HTTP/2 or other modern HTTP versions, which may be a dealbreaker for applications requiring newer protocol features or improved performance.

Low-Level Library Nature

Requires developers to build higher-level features like routing, middleware, and error handling from scratch, adding development overhead compared to more integrated frameworks.

OCaml Ecosystem Dependency

Heavily relies on OCaml tooling (e.g., OPAM) and runtime knowledge, making it inaccessible for teams not already invested in the OCaml ecosystem or seeking cross-language solutions.

Open Source Alternative To

httpaf is an open-source alternative to the following products:

cohttp

cohttp is a lightweight HTTP client and server library for OCaml that provides a simple interface for handling HTTP requests and responses.

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