MyApp.Publishing.APICaller.cs

using Sitecore.Caching;
using Sitecore.Caching.Generics;
using Sitecore.Configuration;
using Sitecore.Diagnostics;
using Sitecore.Sites;
using System;
using System.Collections;

namespace MyApp.Publishing
{
    /// <summary>
    /// Calls an API method hosted in MyExternalApp.
    /// </summary>   
    public class APICaller
    {
        public APICaller()
        {
        }

        /// <summary>
        /// Calls the API method.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="args">The arguments.</param>
        public void CallAPIMethod(object sender, EventArgs args)
        {
            // your code to call the API method goes here
        }
    }
}