Configuration.md

System.ClientModel-based client configuration samples

Configuring retries

To modify the retry policy, create a new instance of ClientRetryPolicy and set it on the ClientPipelineOptions passed to the client constructor.

By default, clients will retry a request three times using an exponential retry strategy with an initial delay of 0.8 seconds and a maximum delay of one minute.

MapsClientOptions options = new()
{
    RetryPolicy = new ClientRetryPolicy(maxRetries: 5),
};

string? key = Environment.GetEnvironmentVariable("MAPS_API_KEY");
ApiKeyCredential credential = new(key!);
MapsClient client = new(new Uri("https://atlas.microsoft.com"), credential, options);

Implement a custom policy

To implement a custom policy that can be added to the client's pipeline, create a class that derives from PipelinePolicy and overide its ProcessAsync and Process methods. The request can be accessed via message.Request. The response is accessible via message.Response, but will have a value only after ProcessNextAsync/ProcessNext has been called.

public class StopwatchPolicy : PipelinePolicy
{
    public override async ValueTask ProcessAsync(PipelineMessage message, IReadOnlyList<PipelinePolicy> pipeline, int currentIndex)
    {
        Stopwatch stopwatch = new();
        stopwatch.Start();

        await ProcessNextAsync(message, pipeline, currentIndex);

        stopwatch.Stop();

        Console.WriteLine($"Request to {message.Request.Uri} took {stopwatch.Elapsed}");
    }

    public override void Process(PipelineMessage message, IReadOnlyList<PipelinePolicy> pipeline, int currentIndex)
    {
        Stopwatch stopwatch = new();
        stopwatch.Start();

        ProcessNext(message, pipeline, currentIndex);

        stopwatch.Stop();

        Console.WriteLine($"Request to {message.Request.Uri} took {stopwatch.Elapsed}");
    }
}

Add a custom policy to the pipeline

Azure SDKs provides a way to add policies to the pipeline at three positions, PerCall, PerTry, and BeforeTransport.

• PerCall policies run once per request

MapsClientOptions options = new();
options.AddPolicy(new StopwatchPolicy(), PipelinePosition.PerCall);

• PerTry policies run each time a request is tried

options.AddPolicy(new StopwatchPolicy(), PipelinePosition.PerTry);

• BeforeTransport policies run after all other policies in the pipeline and before the request is sent by the transport.

Adding policies at the BeforeTransport position should be done with care since changes made to the request by a before-transport policy will not be visible to any logging policies that come before it in the pipeline.

options.AddPolicy(new StopwatchPolicy(), PipelinePosition.BeforeTransport);

Provide a custom HttpClient instance

In some cases, users may want to provide a custom instance of the HttpClient used by a client's transport to send and receive HTTP messages. To provide a custom HttpClient, create a new instance of HttpClientPipelineTransport and pass the custom HttpClient instance to its constructor.

using HttpClientHandler handler = new()
{
    // Reduce the max connections per server, which defaults to 50.
    MaxConnectionsPerServer = 25,

    // Preserve default System.ClientModel redirect behavior.
    AllowAutoRedirect = false,
};

using HttpClient httpClient = new(handler);

MapsClientOptions options = new()
{
    Transport = new HttpClientPipelineTransport(httpClient)
};