When building APIs with ASP.NET Core, it's crucial to explicitly control caching behavior. Unlike web pages where caching often improves user experience, API responses should not be cached by default unless you intentionally design them to be cacheable. Unintended caching can lead to serious issues, including stale data, security vulnerabilities, and hard-to-reproduce bugs. Understanding HTTP caching… [read more]

The Component Object Model (COM) is a fundamental technology in the Windows ecosystem. Even though it was introduced more than 30 years ago, it is still widely used today. In fact, the modern Windows Runtime (WinRT) is built on top of COM. This post explores what COM is, where it comes from, and the problems it solves. What is COM? Imagine you have a box of LEGO bricks. You can connect any brick to any… [read more]

Evaluating recurring date patterns is a common requirement in many applications. Whether you need every day, every Monday at 9 AM, or the last day of each month, you need a reliable way to calculate upcoming occurrences. Meziantou.Framework.Scheduling is a NuGet package that parses and evaluates both CRON expressions and iCalendar recurrence rules (RRule). Installation You can install the package from… [read more]

Roslyn analyzers are great for enforcing coding standards and finding bugs. However, they can sometimes report false positives or warnings you want to ignore in specific contexts. You can suppress these warnings using #pragma directives or [SuppressMessage] attributes, but both approaches require modifying the source code. A DiagnosticSuppressor is a Roslyn component that suppresses diagnostics reported… [read more]

GitHub Actions allows you to create reusable actions. One of the easiest ways to do this is to use Composite Actions, which let you combine multiple steps into a single action. This reduces code duplication across your workflows. When creating a composite action, you may need to reference files stored in the action repository, such as a PowerShell or Bash script. By default, when an action runs, the… [read more]

Working with URLs in .NET applications often involves pattern matching for routing, security policies, or content filtering. While you could write custom regex patterns or string comparisons, there's a better way: the Meziantou.Framework.Uri package brings standardized URL pattern matching to .NET. This package implements the WHATWG URL Pattern API specification, providing a consistent and powerful way to… [read more]

A shard is a deterministic subset of your test suite. Test sharding means splitting one long test run into multiple smaller runs, and executing them in parallel in CI. Instead of waiting for one job that runs every test, you wait for the slowest shard. This often reduces CI wall-clock time and gives faster feedback. Meziantou.ShardedTest is a .NET global tool that creates deterministic shards and runs… [read more]

HTTP caching is one of the most effective ways to improve application performance by reducing network traffic, minimizing server load, and decreasing response times. While browsers automatically implement HTTP caching, the same isn't true for HttpClient in .NET, which processes every request independently without built-in caching support. This post shows how to add standards-compliant HTTP caching to… [read more]

I recently released Meziantou.GitHubActionsTracing, a tool that converts GitHub Actions workflow runs into trace data. This post shows how to use it to debug slow or flaky CI pipelines with timeline-based analysis instead of relying on raw logs alone. Why GitHub Actions runs are hard to diagnose GitHub Actions logs are great for understanding what happened, but not for quickly seeing where time is spent.… [read more]

Windows has long supported case-sensitive file operations, but the feature was not easily accessible or enabled by default. Since Windows 10 (version 1803), case sensitivity can be enabled on a per-directory basis. This feature was introduced primarily to support the Windows Subsystem for Linux (WSL), but any application can take advantage of it. This post covers how to enable case sensitivity for a… [read more]