Tracing calls to downstream HTTP web services with the X-Ray SDK for .NET

When your application makes calls to microservices or public HTTP APIs, you can use the X-Ray SDK for .NET's GetResponseTraced extension method for System.Net.HttpWebRequest to instrument those calls and add the API to the service graph as a downstream service.

Example HttpWebRequest

using System.Net;
using Amazon.XRay.Recorder.Core;
using Amazon.XRay.Recorder.Handlers.System.Net;

private void MakeHttpRequest()
{
  HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://names.example.com/api");
  request.GetResponseTraced();
}

For asynchronous calls, use GetAsyncResponseTraced.

request.GetAsyncResponseTraced();

If you use system.net.http.httpclient, use the HttpClientXRayTracingHandler delegating handler to record calls.

Example HttpClient

using System.Net.Http;
using Amazon.XRay.Recorder.Core;
using Amazon.XRay.Recorder.Handlers.System.Net;

private void MakeHttpRequest()
{
  var httpClient = new HttpClient(new HttpClientXRayTracingHandler(new HttpClientHandler()));
  httpClient.GetAsync(URL);
}

When you instrument a call to a downstream web API, the X-Ray SDK for .NET records a subsegment with information about the HTTP request and response. X-Ray uses the subsegment to generate an inferred segment for the API.

Example Subsegment for a downstream HTTP call

{
  "id": "004f72be19cddc2a",
  "start_time": 1484786387.131,
  "end_time": 1484786387.501,
  "name": "names.example.com",
  "namespace": "remote",
  "http": {
    "request": {
      "method": "GET",
      "url": "https://names.example.com/"
    },
    "response": {
      "content_length": -1,
      "status": 200
    }
  }
}

Example Inferred segment for a downstream HTTP call

{
  "id": "168416dc2ea97781",
  "name": "names.example.com",
  "trace_id": "1-62be1272-1b71c4274f39f122afa64eab",
  "start_time": 1484786387.131,
  "end_time": 1484786387.501,
  "parent_id": "004f72be19cddc2a",
  "http": {
    "request": {
      "method": "GET",
      "url": "https://names.example.com/"
    },
    "response": {
      "content_length": -1,
      "status": 200
    }
  },
  "inferred": true
}