WinUI APIs and C# 15
Today’s selection covers C#-first WinUI, resilient ASP.NET Core APIs, union types, JWT revocation, testing, Docker, and .NET 11.
Jasen's top three picks
- 1 Microsoft.UI.Reactor: a C#-first way to build WinUI apps
Microsoft Dev Blogs
If you caught our session at Microsoft Build 2026 or you've been watching the repo, you've seen this one taking shape in public for a while now, and a lot ha...
- 2 How to Mock External HTTP APIs in .NET Integration Tests
C# Corner
Learn how to mock external HTTP APIs in .NET integration tests with a custom HttpMessageHandler, HttpClient, and xUnit to test successful and error responses...
- 3 FabCon and SQLCon 2026 in Barcelona: Building the data foundation for Microsoft Copilot and agents
Microsoft Azure - Arun Ulag
Microsoft Fabric and SQL innovations announced at FabCon and SQLCon Barcelona 2026 help organizations build trusted data foundations for AI. The post FabCon ...
Editor's note
I’ve kept this edition deliberately broad, from Microsoft.UI.Reactor’s C#-first approach to WinUI through practical API reliability work. The idempotency-key and large JSON streaming pieces are especially useful for teams dealing with real production traffic. I also included the C# 15 union-type discussions because the migration trade-offs deserve more than a passing glance.
Today's articles
Microsoft.UI.Reactor: a C#-first way to build WinUI apps
Microsoft Dev Blogs
If you caught our session at Microsoft Build 2026 or you've been watching the repo, you've seen this one taking shape in public for a while now, and a lot has changed since Build. Here's the longer to...
Topics: C#
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How to Mock External HTTP APIs in .NET Integration Tests
C# Corner
Learn how to mock external HTTP APIs in .NET integration tests with a custom HttpMessageHandler, HttpClient, and xUnit to test successful and error responses reliably.
Topics: REST API Unit Testing xUnit.net
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FabCon and SQLCon 2026 in Barcelona: Building the data foundation for Microsoft Copilot and agents
Microsoft Azure - Arun Ulag
Microsoft Fabric and SQL innovations announced at FabCon and SQLCon Barcelona 2026 help organizations build trusted data foundations for AI. The post FabCon and SQLCon 2026 in Barcelona: Building the ...
Topics: Azure SQL Server
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SQLAlchemy 2.1 brings built-in support for mssql-python
Microsoft Dev Blogs - Matt Hyon
We're pleased to share that SQLAlchemy 2.1.0 is now generally available, with built-in support for mssql-python, Microsoft's Python driver for SQL Server. You can now use it with SQLAlchemy's ORM and ...
Topics: Azure SQL Server
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C# 15 Union Types for API Results: Examples, Trade-Offs, and Migration
Medium
Learn how C# 15 union types simplify ASP.NET Core API results, compare with existing C# patterns, and help you decide when to adopt them.Continue reading on Syncfusion »
Topics: ASP.NET Core C# Web API
Read articleHow to Prevent Duplicate API Requests in ASP.NET Core Using Idempotency Keys
C# Corner
Learn how to prevent duplicate ASP.NET Core API operations with idempotency keys, request validation, stored responses, and SQL Server persistence.
Topics: ASP.NET Core SQL Server Web API
Read articleHow to Return Large JSON Responses in ASP.NET Core Without Loading Everything into Memory
C# Corner
Learn how to stream large JSON responses in ASP.NET Core with Utf8JsonWriter and IAsyncEnumerable to reduce memory usage when exporting database records.
Topics: ASP.NET Core Performance System.Text.Json
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Understanding ASP.NET Core Web APIs
Medium
When we use a website, we interact with a user interface built with technologies such as HTML, CSS, and JavaScript. But behind the scenes…
Topics: ASP.NET Core Web API
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Agentic AI Series — Part 2: How AI Agents Actually Work
C# Corner - Skant Gupta
Topics: OpenAI
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C# 15 Union Types: Examples, Exhaustive Switch and Gotchas
Medium
Last updated: October 22, 2026 · Tested with .NET 11 RC2 (SDK 11.0.100-rc.2.26504.105, C# 15) and the .NET 10.0.12 runtime
Topics: C#
Read articleUnifying Transactional and NLP Signals: Building a Feature Store with Multi-Agent LangGraph RAG
C# Corner - Tuhin Paul
Topics: OpenAI
Read articleUpgrading to .NET 11: 9 Breaking Changes and Fixes
Medium
Last updated: October 24, 2026 · Tested with .NET 11 RC2 (SDK 11.0.100-rc.2.26504.105) against .NET 10.0.12 (SDK 10.0.401), Windows 11
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How to Revoke a JWT Before It Expires
Milan's .NET Weekly
ASP.NET Core validates a JWT by its signature and expiry, so a stolen token keeps working after the user changes their password.
Topics: Authentication JWT Security
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Unwiring WireMock .NET: Elevate Your API Testing
Medium
Overview: WireMock .NET is a free, open-source C# tool that lets integration tests talk to a simulated API over HTTP instead of real…Continue reading on T.8ytes by Titansoft »
Topics: REST API Unit Testing
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How to Read CBOR Data Incrementally in .NET 11
C# Corner
Learn how to read CBOR data incrementally in .NET 11 with CborReader, handle partial input safely, preserve parsing state, and continue when more data arrives.
Topics: C# Performance
Read articleRAG and Microsoft Agent Framework Step By Step (2)
YapCast – Jesse Liberty
In a previous blog post I walked through a RAG example using Microsoft Agent Framework so that we could do a semantic search against our documents. However, Bruno Capuano (Microsoft) and I went over t...
Topics: OpenAI Semantic Kernel
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