This project contains the assignment from Funda.nl.

In order to run the project you will need the following installed

• .NET Core 2.2
• Visual Studio *Community version should be fine!
• NodeJS v10.16.6 *Should install with Visual Studio if you select Node project development

For this project I used the following technologies

• .NET Core 2.2
• React.JS
• C#
• JavaScript
• CSS

Installing the project is straight forward:

1. Clone the Repository by running git clone https://github.com/lakylekidd/funda-assignment.git funda-project
2. Run cd funda-project
3. Run start Funda.sln
4. Right click on the project solution name and select Set StartUp Projects...
5. In the new window select Multiple startup projects
6. For FundaReactClient and FundWebApplication set action to Start
7. Make sure FundaWebApplication is first on the list, use the arrows to arrange the order then click OK
8. Select Start Without Debugging Ctrl + F5.

Wait for the application to download all packages and npm modules and then the client browser window will launch.

Note: For this project to run you need to have ports: 60398, 56219, 5000 and 3000 available. Check launchSettings.json for port configurations for Client and API Projects.

Determine which makelaar's in Amsterdam have the most object listed for sale. Make a table of the top 10. Then do the same thing but only for objects with a tuin which are listed for sale. For the assignment you may write a program in any object oriented language of your choice and you may use any libraries that you find useful.

Tips:

• If you perform too many API requests in a short period of time (>100 per minute), the API will reject the requests. Your implementation should mitigate (avoid) errors and handle any errors that occur, so take both into account.
• Different people will look at your solution, so make sure it is easy to understand and go through.
• We don't expect solutions to have a comprehensive test suite, but we do expect solutions to be testable.

We value creative problem-solving. If you are not sure about implementation details of the exercise, please remember: It is more important to show your competencies than to get "the right answer". Please explain your decisions and thought process.

While the API allows for configuring the number of properties to display in one result, there is a fixed limit of 25 properties. Even if the query includes pageSize=n where n > 25, the limit will still apply.

In order to overcome this we will be implementing some policies based on the article
Implement Http call retries with exponential bacckoff with HttpClientFactory and Polly policies as this is the recommended approach for retries with exponential backoff.

For this we will implement the following function:

static IAsyncPolicy<HttpResponseMessage> GetRetryPolicy()
{
    return HttpPolicyExtensions
        .HandleTransientHttpError()

    #region Status Codes for Retrying
        // Handle 500 status codes
                .OrResult(msg => msg.StatusCode == System.Net.HttpStatusCode.InternalServerError)
                // Handle 502 status codes
                .OrResult(msg => msg.StatusCode == System.Net.HttpStatusCode.BadGateway)
                // Handle 504 status codes
                .OrResult(msg => msg.StatusCode == System.Net.HttpStatusCode.GatewayTimeout)
                // Handle 503 status codes 
                .OrResult(msg => msg.StatusCode == System.Net.HttpStatusCode.ServiceUnavailable)
                // Handle 429 status codes Too Many Requests
                .OrResult(msg => (int)msg.StatusCode == 429)
                // Handle 401 status codes
                .OrResult(msg => msg.StatusCode == System.Net.HttpStatusCode.Unauthorized && msg.ReasonPhrase == "Request limit exceeded")
    #endregion

        // Will retry a maximum of 6 times
        .WaitAndRetryAsync(6, retryAttempt => TimeSpan.FromSeconds(Math.Pow(2, retryAttempt)));
}

And include it inside the ConfigureServices() of the Startup.cs file:

// Configure the client with polly's retry policy
services.AddHttpClient<IFundaService, FundaService>()
    .SetHandlerLifetime(TimeSpan.FromMinutes(5)) // Set the lifetime to 5 minutes
    .AddPolicyHandler(GetRetryPolicy());

In order to prevent any errors, the policy will attempt to retry when the following status codes are encountered

• 500 - Internal Server Error
• 502 - Bad Gateway
• 504 - Gateway Timeout
• 503 - Service Unavailable
• 429 - Too Many Requests
• 401 - Unauthorized with Reason Phrase Request limit exceeded

In order to test the application and make sure the new implementations work, I will be following this article that explains how to better perform integration tests in .NET Core 2.2.