Welcome to CosmosDb.QuickStart

Topic: Configure Connection Policy with reduced Client side latency

Hi! I put together a sample quick start to help you all in optimizing your Cosmos Db .NET SDK integration logic using Microsoft.Azure.Documents.Client.ConnectionPolicy.

Prerequisites

1. Windows 7/8.x/10 with Visual Studio 2015/2017 with .NET Framework 4.5
2. Nuget Package Manager
3. Setup a CosmosDb environment in Azure or use Cosmos Db Emulator (on Windows 10).

How to use the application?

1. Open CosmosDb-QuickStart.sln
2. Do a Nuget package restore.
3. Update the Web.config with your cosmosDb URL and authKey.
4. Launch the solution in debug mode.

Important Files to Consider

Web.config - All the configuration for the connection policy are driven from Web.config-> appSettings, so that application can pick up right state during Run Time based on the configurations defined. There is some hard coded values, which are not made it as configurable.

Constants.cs - I just wanted to simply the way we call ConfigurationManager.AppSettings, by defining them only once as a static readonly variable.

  //Constants.cs -> Snippet
  public static readonly string database = ConfigurationManager.AppSettings["database"];
  public static readonly string collection = ConfigurationManager.AppSettings["collection"];

  public static readonly string endpoint = ConfigurationManager.AppSettings["endpoint"];
  public static readonly string authKey = ConfigurationManager.AppSettings["authKey"];

  public static readonly string connectionMode = ConfigurationManager.AppSettings["connectionMode"];
  public static readonly string connectionProtocol = ConfigurationManager.AppSettings["connectionProtocol"];

  public static readonly int maxConnectionLimit = Convert.ToInt32(ConfigurationManager.AppSettings["maxConnectionLimit"]);

CosmosDbRepository.cs - Refer to the Initialize method.

   //Default: Direct Mode, based on appSettings configuration, application would pick up right connection mode in Run Time.
   var connectionMode = Constants.connectionMode.Trim().Equals("direct", StringComparison.OrdinalIgnoreCase) ? ConnectionMode.Direct : ConnectionMode.Gateway;                                                                                                                                                 
   
   //Default: HTTPS, based on appSettings configuration, application would pick up right connection mode in Run Time.
   var connectionProtocol = Constants.connectionProtocol.Trim().Equals("tcp", StringComparison.OrdinalIgnoreCase) ? Protocol.Tcp : Protocol.Https;
   var maxConnectionLimit = Constants.maxConnectionLimit;
   //Setting up a Connection Policy to be passed on while creating DocumentClient
   ConnectionPolicy connectionPolicy = new ConnectionPolicy
   {
          ConnectionMode = connectionMode,
          ConnectionProtocol = connectionProtocol,
          MaxConnectionLimit = maxConnectionLimit,
          RetryOptions = new RetryOptions() { MaxRetryAttemptsOnThrottledRequests = 5, MaxRetryWaitTimeInSeconds = 5 } // setting a retry for Connection Throttling and Retry.
   };
   client = new DocumentClient(new Uri(Constants.endpoint), Constants.authKey, connectionPolicy);

ProTip: Source code is provided as is based on CosmosDb Basic ToDo starter application and I customized it to showcase the ConnectionPolicy implementation.

More Reads: If you want to learn about ConnectionPolicy class, you can read here.