Multi-Tier Integration Service

Created: C# Service for integrating multi-tier applications

Updated: 03 September 2023

For applications that span multiple tiers or make use of a separate data accesss and web application layers a generic integration service can be used to communicate between tiers

Service Definition

The service enables you to call controllers on the underlying tier by their route, provided that complex objects are supplied in the request body where needed

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public class IntegrationService
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{
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    private string _apiBaseUrl;
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    private WebProxy _proxy;
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    public IntegrationService(string apiBaseUrl, WebProxy proxy = null)
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    {
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        _apiBaseUrl = apiBaseUrl;
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        _proxy = proxy;
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    }
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    /// <summary>
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    /// Creates a new HttpClient instance that can be used to make HTTP requests to the API endpoint with the endpoint and proxy precofigured
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    /// Supports basic HTTP methods and configurations. Essentially enables client to call a function on another application's route with
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    /// params as a single POST DTO if necessary
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    /// </summary>
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    /// <returns></returns>
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    public HttpClient GetClient()
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    {
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        HttpClient client;
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        if (_proxy != null)
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        {
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            var handler = new HttpClientHandler()
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            {
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                Proxy = _proxy
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            };
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            client = new HttpClient(handler);
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        }
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        else
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        {
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            client = new HttpClient();
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        }
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        client.BaseAddress = new Uri(_apiBaseUrl);
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        return client;
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    }
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    #region GET Methods
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    public async Task<string> Get(string path)
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    {
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        using (var client = GetClient())
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        {
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            var response = await client.GetStringAsync(path);
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            return response;
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        }
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    }
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    public async Task<T> Get<T>(string path)
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    {
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        using (var client = GetClient())
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        {
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            var response = await client.GetStringAsync(path);
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            var data = JsonConvert.DeserializeObject<T>(response);
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            return data;
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        }
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    }
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    #endregion
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    #region POST Methods
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    public async Task<string> Post(string path, object requestData)
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    {
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        using (var client = GetClient())
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        {
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            var requestContent = new StringContent(
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                JsonConvert.SerializeObject(requestData),
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                Encoding.UTF8,
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                "application/json"
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            );
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            var response = await client.PostAsync(path, requestContent);
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            var responseString = await response.Content.ReadAsStringAsync();
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            return responseString;
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        }
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    }
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    public async Task<T> Post<T>(string path, object requestData)
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    {
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        using (var client = GetClient())
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        {
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            var requestContent = new StringContent(
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                JsonConvert.SerializeObject(requestData),
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                Encoding.UTF8,
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                "application/json"
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            );
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            var response = await client.PostAsync(path, requestContent);
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            var responseString = await response.Content.ReadAsStringAsync();
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            var data = JsonConvert.DeserializeObject<T>(responseString);
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            return data;
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        }
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    }
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    #endregion
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    #region PUT Methods
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    public async Task<string> Put(string path, object requestData)
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    {
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        using (var client = GetClient())
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        {
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            var requestContent = new StringContent(
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                JsonConvert.SerializeObject(requestData),
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                Encoding.UTF8,
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                "application/json"
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            );
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            var response = await client.PutAsync(path, requestContent);
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            var responseString = await response.Content.ReadAsStringAsync();
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            return responseString;
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        }
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    }
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    public async Task<T> Put<T>(string path, object requestData)
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    {
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        using (var client = GetClient())
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        {
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            var requestContent = new StringContent(
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                JsonConvert.SerializeObject(requestData),
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                Encoding.UTF8,
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                "application/json"
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            );
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            var response = await client.PutAsync(path, requestContent);
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            var responseString = await response.Content.ReadAsStringAsync();
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            var data = JsonConvert.DeserializeObject<T>(responseString);
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            return data;
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        }
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    }
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    #endregion
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    #region DELETE Methods
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    public async Task<string> Delete(string path)
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    {
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        using (var client = GetClient())
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        {
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            var response = await client.DeleteAsync(path);
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            var responseString = await response.Content.ReadAsStringAsync();
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            return responseString;
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        }
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    }
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    public async Task<T> Delete<T>(string path)
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    {
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        using (var client = GetClient())
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        {
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            var response = await client.DeleteAsync(path);
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            var responseString = await response.Content.ReadAsStringAsync();
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            var data = JsonConvert.DeserializeObject<T>(responseString);
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            return data;
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        }
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    }
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    #endregion
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}
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/// <summary>
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/// Proxy settings, needed for accessing accross tiers
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/// </summary>
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public class ProxySettings
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{
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    public string Endpoint { get; set; }
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    public bool BypassOnLocal { get; set; } = true;
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    public bool EnvironmentHasProxy() => !string.IsNullOrEmpty(Endpoint);
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}

Confugure the Service

You can configure the service in your startup.cs as follows:

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 services.AddScoped<IntegrationService>(s =>
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  {
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      var proxySettings = Configuration
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          .GetSection("ProxySettings")
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          .Get<ProxySettings>();
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      var intBaseUrl = Configuration.GetValue<string>("IntegrationUrl");
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      if (proxySettings.EnvironmentHasProxy())
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      {
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          var proxy = new WebProxy(
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              proxySettings.Endpoint,
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              proxySettings.BypassOnLocal
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          );
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          return new IntegrationService(intBaseUrl, proxy);
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      }
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      else
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      {
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          return new IntegrationService(intBaseUrl);
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      }
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  });

The above is a bit overkill as it does the proxy checking too, but you don’t need that if you know your proxy configuration beforehand or are not using a proxy

Using the Service

To use the service you need to request it in a controller constructor via Dependency Injection

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public class MyController : Controller {
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  private IntegrationService _integrationService;
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  public MyController(IntegrationService integrationService)
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  {
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    _integrationService = integrationService;
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  }
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  public async task<MyObject> MyFunction(ComplexObject data)
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  {
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    var result = await integrationService.Post<MyObject>("api/DoStuff", data);
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    return result;
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  }
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}

You will need the following in your appsettings.json

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...,
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"ProxySettings: {
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    "Endpoint": "",
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    "BypassOnLocal": true
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},
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...