Difference between PUT and POST using WCF REST

Question

I have tried to implement a REST WCF in order to explore difference between PUT and POST verb. I have uploded a file in a location using the service.

The service implementation is as folowing:

[OperationContract]
[WebInvoke(UriTemplate = "/UploadFile", Method = "POST")]
void UploadFile(Stream fileContents);

public void UploadFile(Stream fileContents)
{
 byte[] buffer = new byte[32768];
 MemoryStream ms = new MemoryStream();
 int bytesRead, totalBytesRead = 0;
 do
 {
       bytesRead = fileContents.Read(buffer, 0, buffer.Length);
       totalBytesRead += bytesRead;

       ms.Write(buffer, 0, bytesRead);
  } while (bytesRead > 0);

  using (FileStream fs = File.OpenWrite(@"C:\temp\test.txt")) 
  { 
      ms.WriteTo(fs); 
   }

  ms.Close();

}

Client code is as following:

HttpWebRequest request =     (HttpWebRequest)HttpWebRequest.Create("http://localhost:1922   /EMPRESTService.svc/UploadFile");
        request.Method = "POST";
        request.ContentType = "text/plain";

        byte[] fileToSend = File.ReadAllBytes(@"C:\TEMP\log.txt");  // txtFileName contains the name of the file to upload. 
        request.ContentLength = fileToSend.Length;

        using (Stream requestStream = request.GetRequestStream())
        {
            // Send the file as body request. 
            requestStream.Write(fileToSend, 0, fileToSend.Length);
            //requestStream.Close();
        }

        using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            Console.WriteLine("HTTP/{0} {1} {2}", response.ProtocolVersion, (int)response.StatusCode, response.StatusDescription);
        Console.ReadLine();

The file is being uploaded and the response status code is being returned as "200 OK". The satus code is same in case of existance or non-existance of the file in the upload location.

I have changed the REST verb to PUT and the status code is same as above.

Could anybody explain, how I can identify the differences between the verbs in this context? I couldn't able to simulate generating continious request fron client code. If the behaviour will differ on doing so, could anybody help me in modifying the client code in ordrr to send continious request in a row ?

Answer 1

POST verb is used when are you creating a new resource (a file in your case) and repeated operations would create multiple resources on the server. This verb would make sense if uploading a file with the same name multiple times creates multiple files on the server.

PUT verb is used when you are updating an existing resource or creating a new resource with a predefined id. Multiple operations would recreate or update the same resource on the server. This verb would make sense if uploading a file with the same name for the second, third... time would overwrite the previously uploaded file.