Fundalyzer
Instructions
Run the Api project. A swagger UI page should open where you can perform 2 get requests.
You have to wait for the requests to work because of the BackgroundService that is pulling data from Funda in the meanwhile.
Justification
For this project I used .NET 7 and C# 11 (because: new). I acknowledge this .NET version is not LTS.
The design of the code is quite elaborate, but it showcases how I would set up an application using a DDD approach.
Api
This API of this solution is completely not RESTful or according to any standard. It is just a way to retrieve data from the application.
Funda Api
I checked if Funda has an OpenAPI / Swagger definition, but unfortunately it doesn't It would have been perfect because you could easily generate a client with NSwag / Swashbuckle. I preferred to use JSON instead of XML, because XML is older and I prefer the readability of JSON and I prefer its tooling.
Background job
I wanted to use Quartz as a job schedule. Quartz.NET is an advanced scheduler with a built-in mechanism to persist scheduled jobs, and much more.
But it is a bit overkill for this application and therefore I used a simpler approach:
When the application starts, a background job starts which uses the new .NET PeriodicTimer.
The usage of a background job has a disadvantage:
when you need to scale up the performance by running more instances of the API, multiple background task will run simultaneously.
Domain modeling
I modelled my domain with a DDD onion design using my own DDD modeling package: https://github.com/Code-Chops/DomainModeling.
Value objects
Throughout my code I use value objects which have structural equality. These are generated using a source generator, so a lot of boiler-plate does not have to be written, e.g.: structure equality, casts, constructors, factories, and validation.
Entities / Identities
The 2 entities in the domain model Agency and Estate both have a strongly typed primary ID that is auto-generated using source generators.
Contracts
I used my package https://github.com/Code-Chops/Contracts (which is in beta) for easily creating contracts, adapters and using JSON serializers.
Validation
I am not satisfied yet with the design of the error codes (which you see at the value objects). And especially with the usage of nameof().
These error codes ensure that error responses to external sources are unified and can eventually be parsed and localized to the end user.
In my spare time I am creating a way to unify these error codes in a single MagicEnum, see my MagicEnum package: https://github.com/Code-Chops/MagicEnums.
These error messages (and their parameters) can be localized in a Blazor client using my package https://github.com/Code-Chops/LightResources.
Rate limiting
The background job polls the Funda API once a second (is configurable).
Also included in the FundaHttpClient is a RateLimitingStrategy which determines how the application should handle when an HTTP status code of TooManyRequests is received from Funda.
Tests
Many more unit and integration tests can be added. For example, the *.http files in Api could be placed in an integration test.