Send commands, fetch queries, and broadcast events using a mediator pattern for CQRS+ES — For the last few years, Command Query Responsibility Segregation (CQRS) and Event Sourcing (ES) emerged as patterns that can help implement large scale systems, with some risky complexity, by having different models to read or mutate data while also using events as a single source of truth. Since there are…

Performance comparison between ToList and ToArray — Ever since Microsoft introduced Language Integrated Query to the .NET framework (also known as LINQ) developers have been using it extensively to work with collections. From a simple filter, to an aggregation, to a transformation, LINQ is the technology of choice to keep code clean and readable. …

Comparison between Frozen, Immutable and Dictionary — Microsoft’s upcoming release of .NET 8 will introduce a lot of new features that will certainly be welcomed by the developer community, making it an even stronger framework for application development. One of those features is the namespace System.Collections.Frozen that introduces two new collections: FrozenDictionary and FrozenSet. These new types…

Using C# records and Entity Framework Core to implement immutable data access layers — Nowadays, when implementing a .NET application that works directly with a database (relational or not), most developers will chose Entity Framework Core to abstract their data layer and work directly with entity classes. It has become an integral part of the .NET ecosystem, just like ASP.NET, and it is extremely…

Overcoming limitations or performance bottlenecks by executing raw SQL with Dapper — Nowadays it is extremely rare to implement an application without using any sort of library for Object-Relational Mapping (ORM) to reduce development time by removing the need to implement a lot of boilerplate code to access a database. In the .NET …

Audit commands and store events with transversal behavior — When implementing a web application, it can be a good idea to enforce some kind of auditing to all of your client interactions, either to track their behavior over time, to ensure any security breach will be properly logged, or just to help analyze system bugs. Previously we talked about…

Manage Entity Framework Core transactions when handling commands — When implementing a simplified CQRS service, which usually has a single database but still separates commands from queries, the mediator pipeline can be used to manage transactions when processing commands, ensuring changes will be implicitly committed unless an exception is thrown. Implementing a pipeline for transactions has some key advantages…

Validate commands, events or queries with transversal behavior — When implementing web applications that manipulate information, there is always the need to validate data sent by the clients, ensuring business rules are properly implemented. Previously I talked about the implementation of Command Query Responsibility Segregation (CQRS) and Event Sourcing (ES) using a mediator pattern and how to support transversal…

Intercept commands, queries and events to apply transversal behavior — In my previous article I explained how you could implement Command Query Responsibility Segregation (CQRS) and Event Sourcing (ES) patterns using a mediator instance from SimpleSoft.Mediator in ASP.NET Core applications. This time I’m going to explain how to intercept commands, queries and events, making it possible to apply transversal behavior…