Messages / reply messages when using HttpClient

Question

I have a method that does POST as shown below

var response = await client.PostAsJsonAsync(url, entity); if (response.IsSuccessStatusCode) { // read the response as strongly typed object return await response.Content.ReadAsAsync<T>(); } 

My question is how can I get the actual JSON that was sent from the entity object. I would like to register JSON that gets POSTED, so it would be nice if I did not serialize json myself.

Answer 1

An example of how you could do this:

Some notes:

• LoggingHandler intercepts the request before it processes it before the HttpClientHandler , which finally writes to the wire.

• PostAsJsonAsync extension internally creates an ObjectContent and when ReadAsStringAsync() is called in the LoggingHandler , it calls the formatter inside the ObjectContent to serialize the object and that is the reason you see the content in json.

Log Handler:

 public class LoggingHandler : DelegatingHandler { public LoggingHandler(HttpMessageHandler innerHandler) : base(innerHandler) { } protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { Console.WriteLine("Request:"); Console.WriteLine(request.ToString()); if (request.Content != null) { Console.WriteLine(await request.Content.ReadAsStringAsync()); } Console.WriteLine(); HttpResponseMessage response = await base.SendAsync(request, cancellationToken); Console.WriteLine("Response:"); Console.WriteLine(response.ToString()); if (response.Content != null) { Console.WriteLine(await response.Content.ReadAsStringAsync()); } Console.WriteLine(); return response; } } 

The chain above the LoggingHandler with HttpClient :

 HttpClient client = new HttpClient(new LoggingHandler(new HttpClientHandler())); HttpResponseMessage response = client.PostAsJsonAsync(baseAddress + "/api/values", "Hello, World!").Result; 

Output:

 Request: Method: POST, RequestUri: 'http://kirandesktop:9095/api/values', Version: 1.1, Content: System.Net.Http.ObjectContent`1[ [System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]], Headers: { Content-Type: application/json; charset=utf-8 } "Hello, World!" Response: StatusCode: 200, ReasonPhrase: 'OK', Version: 1.1, Content: System.Net.Http.StreamContent, Headers: { Date: Fri, 20 Sep 2013 20:21:26 GMT Server: Microsoft-HTTPAPI/2.0 Content-Length: 15 Content-Type: application/json; charset=utf-8 } "Hello, World!" 

Answer 2

See http://mikehadlow.blogspot.com/2012/07/tracing-systemnet-to-debug-http-clients.html

To configure the System.Net listener to output to the console and the log file, add the following to the assembly configuration file:

 <system.diagnostics> <trace autoflush="true" /> <sources> <source name="System.Net"> <listeners> <add name="MyTraceFile"/> <add name="MyConsole"/> </listeners> </source> </sources> <sharedListeners> <add name="MyTraceFile" type="System.Diagnostics.TextWriterTraceListener" initializeData="System.Net.trace.log" /> <add name="MyConsole" type="System.Diagnostics.ConsoleTraceListener" /> </sharedListeners> <switches> <add name="System.Net" value="Verbose" /> </switches> </system.diagnostics> 

Answer 3

Network tracing is also available for the following objects (see msdn article)

• System.Net.Sockets Some public methods of the Socket, TcpListener, TcpClient, and Dns classes
• System.Net Some public methods of the HttpWebRequest, HttpWebResponse, FtpWebRequest and FtpWebResponse classes, as well as SSL debugging information (invalid certificates, list of missing issuers, and client certificate errors.)
• System.Net.HttpListener Some public methods of the HttpListener, HttpListenerRequest, and HttpListenerResponse classes.
• System.Net.Cache Some private and internal methods in System.Net.Cache.
• System.Net.Http Some public methods of the classes HttpClient, DelegatingHandler, HttpClientHandler, HttpMessageHandler, MessageProcessingHandler, and WebRequestHandler.
• System.Net.WebSockets.WebSocket Some public methods of the ClientWebSocket and WebSocket classes.

Put the following lines of code in the configuration file

 <configuration> <system.diagnostics> <sources> <source name="System.Net" tracemode="includehex" maxdatasize="1024"> <listeners> <add name="System.Net"/> </listeners> </source> <source name="System.Net.Cache"> <listeners> <add name="System.Net"/> </listeners> </source> <source name="System.Net.Http"> <listeners> <add name="System.Net"/> </listeners> </source> <source name="System.Net.Sockets"> <listeners> <add name="System.Net"/> </listeners> </source> <source name="System.Net.WebSockets"> <listeners> <add name="System.Net"/> </listeners> </source> </sources> <switches> <add name="System.Net" value="Verbose"/> <add name="System.Net.Cache" value="Verbose"/> <add name="System.Net.Http" value="Verbose"/> <add name="System.Net.Sockets" value="Verbose"/> <add name="System.Net.WebSockets" value="Verbose"/> </switches> <sharedListeners> <add name="System.Net" type="System.Diagnostics.TextWriterTraceListener" initializeData="network.log" /> </sharedListeners> <trace autoflush="true"/> </system.diagnostics> </configuration> 

Answer 4

The easiest solution is to use Wireshark and trace the tcp HTTP stream.