Compressing Web API Responses Using DotNetZip

Click on the Header tab and see the Content-Length below image.

Now, we are going to see content size after the addition of the DotnetZip Library and using the compression technique.

First of all, we have to install DotnetZip Library through "Manage NuGet packages".

Now, add one new folder as Filters and add one class inside this folder as GzipCompression.cs.

Write the below code on this page.

using System.IO;
using System.Net.Http;
using System.Web.Http.Filters;
namespace CompressingWebAPIResponse.Filters
{
    public class GzipCompressionAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuted(HttpActionExecutedContext actionContext)
        {
            var content = actionContext.Response.Content;
            var bytes = content == null ? null : content.ReadAsByteArrayAsync().Result;
            var zlibbedContent = bytes == null ? new byte[0] : CompressionHelper.GzipByte(bytes);
            actionContext.Response.Content = new ByteArrayContent(zlibbedContent);
            actionContext.Response.Content.Headers.Remove("Content-Type");
            actionContext.Response.Content.Headers.Add("Content-encoding", "gzip");
            actionContext.Response.Content.Headers.Add("Content-Type", "application/json");
            base.OnActionExecuted(actionContext);
        }
    }
    public class CompressionHelper
    {
        public static byte[] GzipByte(byte[] str)
        {
            if (str == null)
            {
                return null;
            }
            using (var output = new MemoryStream())
            {
                using (var compressor = new Ionic.Zlib.GZipStream(output, Ionic.Zlib.CompressionMode.Compress, Ionic.Zlib.CompressionLevel.BestSpeed))
                {
                    compressor.Write(str, 0, str.Length);
                }
                return output.ToArray();
            }
        }
    }
}

In the code given above, we are inheriting the ActionFilterAttribute class for overriding the OnActionExecuted Method and we also need a helper class to perform compression.

Now, just put this ActionFilter attribute above the GetEmployeeData method, as shown below.

[GzipCompression]
public IHttpActionResult GetEmployeeData()
{
    List<Employee> employee = new List<Employee>
    {
        new Employee { Id = "1", Name = "Vivek", Address = "Hyderabad" },
        new Employee { Id = "2", Name = "Ranjeet", Address = "Hyderabad" },
        new Employee { Id = "3", Name = "Ganesh", Address = "Hyderabad" },
        new Employee { Id = "4", Name = "Gajanan", Address = "Hyderabad" },
        new Employee { Id = "5", Name = "Vijay", Address = "Hyderabad" },
        new Employee { Id = "6", Name = "Ashish", Address = "Hyderabad" },
        new Employee { Id = "7", Name = "Praveen", Address = "Hyderabad" },
        new Employee { Id = "8", Name = "Santosh", Address = "Hyderabad" }
    };

    return Ok(employee);
}

Below is the image of the same request with compressed data using gzip compression.

Here, we can clearly see the difference in Content-Length which is changed from 395 to 144. We can also use this code for Controller level compression as per our requirement.

In this easy way, we can compress large response data and increase application performance.