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• Introduction
• Packages
  • CommandQuery ⚙️
  • CommandQuery.AspNetCore 🌐
  • CommandQuery.AWSLambda ⚡
  • CommandQuery.AzureFunctions ⚡
  • CommandQuery.GoogleCloudFunctions ⚡
  • CommandQuery.Client 🧰
• Upgrading
• Acknowledgements

Command Query Separation (CQS) for .NET and C#

• Build services that separate the responsibility of commands and queries
• Focus on implementing the handlers for commands and queries
• Create APIs with less boilerplate code

Available for:

🌐 ASP.NET Core⚡ AWS Lambda⚡ Azure Functions⚡ Google Cloud Functions

Command Query Separation?

Queries: Return a result and do not change the observable state of the system (are free of side effects).

Commands: Change the state of a system but do not return a value.

—Martin Fowler

In other words:

• Commands
  • Writes (create, update, delete) data
• Queries
  • Reads and returns data

The traditional approach that commandsdo not return a value is a bit inconvenient.

CommandQuery has a pragmatic take and supports both commands with and without result 👍

Command Query Separation for .NET

• 📃 README:CommandQuery.md
• 💁 Samples:
  • CommandQuery.Sample.Contracts
  • CommandQuery.Sample.Handlers

Command Query Separation for ASP.NET Core

• 📃 README:CommandQuery.AspNetCore.md
• 💁 Samples:
  • CommandQuery.Sample.AspNetCore
  • CommandQuery.Sample.AspNetCore.Tests

Command Query Separation for AWS Lambda

• 📃 README:CommandQuery.AWSLambda.md
• 💁 Samples:
  • CommandQuery.Sample.AWSLambda
  • CommandQuery.Sample.AWSLambda.Tests

Command Query Separation for Azure Functions

• 📃 README:CommandQuery.AzureFunctions.md
• 💁 Samples:
  • CommandQuery.Sample.AzureFunctions
  • CommandQuery.Sample.AzureFunctions.Tests

Command Query Separation for Google Cloud Functions

• 📃 README:CommandQuery.GoogleCloudFunctions.md
• 💁 Samples:
  • CommandQuery.Sample.GoogleCloudFunctions
  • CommandQuery.Sample.GoogleCloudFunctions.Tests

Clients for CommandQuery APIs

• 📃 README:CommandQuery.Client.md
• 💁 Samples:
  • CommandQuery.Sample.Client

⬆️ Upgrading from version3.0.0 to4.0.0

Upgrade AspNetCore:

• Upgrade the project target framework tonet8.0

Upgrade AWSLambda:

• Upgrade the project target framework tonet8.0

Upgrade AzureFunctions:

• Upgrade the project target framework tonet8.0
• Remove thelogger argument fromHandleAsync
• Consider to use theHttpRequest versions ofHandleAsync

Upgrade GoogleCloudFunctions:

• Upgrade the project target framework tonet8.0
• Remove thelogger argument fromHandleAsync

Inspired bySteven van Deursen blog posts:

• Meanwhile... on the command side of my architecture
• Meanwhile... on the query side of my architecture