Monitoring

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Overview

Event Types
Subscribing to Events
API Documentation

Overview

On this page, you can learn how to configure monitoring in the MongoDB .NET/C# Driver. Monitoring is the process of gathering information about your application's performance and resource usage as it runs. This can help you make informed decisions when designing and debugging your application.

The driver provides information about your application by emitting events. You can subscribe to these driver events to monitor your application.

Note

Event Logging

This page explains how to monitor your application in code. To learn how to record this information to an external log, see Logging.

Event Types

The type of event that the driver emits depends on the operation being performed. The following table describes the types of events that the driver emits:

Event Type	Description
Command Events	Events related to MongoDB database commands, such as `find`, `insert`, `delete`, and `count`. To learn how to use the .NET/C# Driver to run a database command, see Run a Database Command. For more information about MongoDB database commands, see Database Commands in the MongoDB Server manual. As a security measure, the driver redacts the contents of some command events. This protects the sensitive information contained in these command events.
Server Discovery and Monitoring (SDAM) Events	Events related to changes in the state of the MongoDB deployment.
Connection Pool Events	Events related to the connection pool held by the driver.

For a complete list of events the driver emits, see the API documentation for the MongoDB.Driver.Core.Events namespace.

Subscribing to Events

To monitor an event, you must subscribe a listener method on your MongoClient instance. The following steps describe how to subscribe to events:

Create a MongoClientSettings object.
Set the ClusterConfigurator property on the MongoClientSettings object to a lambda function that accepts a ClusterBuilder object.
In the lambda function, call the Subscribe<TEvent>() method on the ClusterBuilder object for each event you want to subscribe to. Replace TEvent with the event type. Pass the event handler method as an argument to the Subscribe<TEvent>() method.

The following code example shows how to subscribe to the ClusterOpenedEvent, ServerHeartbeatSucceededEvent, and ConnectionPoolReadyEvent. This example assumes that the ClusterEventHandler, HeartbeatEventHandler, and ConnectionPoolEventHandler methods are defined elsewhere in your code.

var clientSettings = MongoClientSettings.FromConnectionString(MongoConnectionString);
clientSettings.ClusterConfigurator = clusterBuilder =>
{
    clusterBuilder
      .Subscribe<ClusterOpenedEvent>(ClusterEventHandler)
      .Subscribe<ServerHeartbeatSucceededEvent>(HeartbeatEventHandler)
      .Subscribe<ConnectionPoolReadyEvent>(ConnectionPoolEventHandler);
};

Tip

You can subscribe to any number of events, and these events can be of different types.

API Documentation

To learn more about the methods and classes used to monitor events in the driver, see the following API documentation:

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