How to make REST requests with C#

AdamNThompson

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21 Nov 2012CPOL2 min read

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A reusable component for makeing REST service requests using C#

Introduction

REST web services have become mainstream and it is important as a developer to know how to communicate with the onslaught of services built using this architecture which now flood our industry. In this article I will provide you with a module I developed for making web request to REST services using C# and give you some details on how the code works.

Explaining what REST services are and how they work is beyond the scope of this modest article. However, if you are unfamiliar with the basic concepts I recommend you ready this article and get up to speed.

Background

This class I'm going to share with you is one I developed for simplifying RESTful service calls using C#. It has served me well over the years and is in production use all over the place. Hopfully it saves you some time and adds something usful to your arsenal.

Using the code

Using the code is pretty straightforward. You just create an instance of the RestClient class, assign the value of your endpoint (the endpoint is the URL of the REST service you are attempting to call), and call the MakeRequest method.

Basic call

string endPoint = @"http:\\myRestService.com\api\";
var client = new RestClient(endPoint);
var json = client.MakeRequest();

If you want to append parameters you can pass them into the make request method like so.

var json = client.MakeRequest("?param=0");

To set the HttpVerb (i.e. GET, POST, PUT, or DELETE), simply use the provided HttpVerb enumeration. Here is an expample of making a POST request:

var client = new RestClient(endpoint: endPoint, 
                            method: HttpVerb.POST, 
                            postData: "{'someValueToPost': 'The Value being Posted'}");

You can also just assign the values in line if you want:

var client = new RestClient();
client.EndPoint = @"http:\\myRestService.com\api\"; ;
client.Method = HttpVerb.POST;
client.PostData = "{postData: value}";
var json = client.MakeRequest();

The Code

using System;
using System.IO;
using System.Net;
using System.Text;

public enum HttpVerb
{
    GET,
    POST,
    PUT,
    DELETE
}

namespace HttpUtils
{
  public class RestClient
  {
    public string EndPoint { get; set; }
    public HttpVerb Method { get; set; }
    public string ContentType { get; set; }
    public string PostData { get; set; }

    public RestClient()
    {
      EndPoint = "";
      Method = HttpVerb.GET;
      ContentType = "text/xml";
      PostData = "";
    }
    public RestClient(string endpoint)
    {
      EndPoint = endpoint;
      Method = HttpVerb.GET;
      ContentType = "text/xml";
      PostData = "";
    }
    public RestClient(string endpoint, HttpVerb method)
    {
      EndPoint = endpoint;
      Method = method;
      ContentType = "text/xml";
      PostData = "";
    }

    public RestClient(string endpoint, HttpVerb method, string postData)
    {
      EndPoint = endpoint;
      Method = method;
      ContentType = "text/xml";
      PostData = postData;
    }


    public string MakeRequest()
    {
      return MakeRequest("");
    }

    public string MakeRequest(string parameters)
    {
      var request = (HttpWebRequest)WebRequest.Create(EndPoint + parameters);

      request.Method = Method.ToString();
      request.ContentLength = 0;
      request.ContentType = ContentType;

      if (!string.IsNullOrEmpty(PostData) && Method == HttpVerb.POST)
      {
        var encoding = new UTF8Encoding();
        var bytes = Encoding.GetEncoding("iso-8859-1").GetBytes(PostData);
        request.ContentLength = bytes.Length;

        using (var writeStream = request.GetRequestStream())
        {
          writeStream.Write(bytes, 0, bytes.Length);
        }
      }

      using (var response = (HttpWebResponse)request.GetResponse())
      {
        var responseValue = string.Empty;

        if (response.StatusCode != HttpStatusCode.OK)
        {
          var message = String.Format("Request failed. Received HTTP {0}", response.StatusCode);
          throw new ApplicationException(message);
        }

        // grab the response
        using (var responseStream = response.GetResponseStream())
        {
          if (responseStream != null)
            using (var reader = new StreamReader(responseStream))
            {
              responseValue = reader.ReadToEnd();
            }
        }

        return responseValue;
      }
    }

  } // class

}

How it works

The HttpWebRequest object in the System.Net namespace does all the heavy lifting. It makes the web request and has properties to defign how you want the request submitted across the web. From there I'm reading the response stream and returning it. The rest is just basic class design used to encapselate the functionality into a reusable component. I hope it serves you well Smile | :)

History

11/21/2010 - Posted article w/samples.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Written By

AdamNThompson

Web Developer

United States

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