Laszlo

Hello, I am Laszlo

Software-Engineer, .NET developer

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Cancellation and Application Shutdown in an HTTP Server

I work on a personal project to build an ASP.NET Core server to serves HTTP/2 and HTTP/3 request-response pairs. This server integrates with ASP.NET Core applications, providing an alternative to Kestrel, IIS, HTTP.sys, and similar servers.

In most codebases I've encountered, significant effort goes into optimizing the startup process—starting the host, registering types, initializing background services, and establishing downstream connections. The goal is usually to achieve the fastest and most efficient application initialization. However, it's much less common for applications to pay the same attention to the shutdown process. That’s the focus of this post.

For server applications, there's often an assumption that requests are retriable. If a request is interrupted due to application shutdown, the client can simply retry. However, HTTP only guarantees safe retries for idempotent verbs and compliant servers.

At the infrastructure level, sophisticated hosting solutions can drain all active HTTP connections before terminating the server process. In a less controlled environments, a process might be terminated abruptly, without draining connections or even sending a SIGINT (CTRL+C) or SIGTERM signal.

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Prefixed Integer Encoding with SIMD

HTTP/3 uses QPACK to encode header fields. QPACK uses the prefixed integer encoding from RFC 7541.

In a previous post I explored this encoding and compared it with QUIC's Variable Length Integer Encoding. That comparison considered using SIMD for prefixed-integer decoding.

This post explores encoding prefixed integers using SIMD.

Prefixed Integer Encoding

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Integer Decoding with HTTP/3

HTTP/3 uses 2 different types of integer encoding in a transitive way. This blog post compares these encodings from size, decoding performance, and decoding complexity perspectives. These encodings are:

  • variable-length integer encoding defined by QUIC-TRANSPORT
  • prefixed integer encoding defined by HPACK

Seeing HPACK might be surprising as HTTP/3 uses QPACK for field compression. QPACK does not define the prefixed integer encoding; it inherits it from HPACK.

Both encodings encode positive integer numbers and zero.

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Try-Catch-Finally in C#

Introduction

C#'s try-catch-finally statements are fundamental building blocks of the language. While most developers learn exception handling early in their careers and use it frequently in production applications, the mechanics can be surprisingly complex. Exception handling is often discussed during developer job interviews, and even experienced developers can struggle with some of its nuances.

A Complex Case

Let's examine a challenging code snippet that demonstrates these complexities. What does the following code print to the console?

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Cryptographic Signatures with a TPM

In my previous post, I compared different signature algorithms listed primarily in RFC 9421, extended with MLDsa44. The focus of that comparison was performance rather than cryptographic strength. I ran the tests on multiple hardware configurations and operating systems, but performed the signing in software.

In this post, I use Windows and a TPM to sign data. The TPM protects the private key and performs the private key operation, while public key operations may be handled by the provider or operating system The test setup matches the previous tests as closely as possible.

Message sizes:

  • A small message, roughly the size of a single JSON property value.
  • A medium message, where the plaintext is roughly the size of a few properties (93 bytes).
  • A 1 KB message.

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