Friday, 12 July 2013

Hosting a RESTful JSON WCF Service from a console app or a windows service.

I've been working for a while on an application, too long to explain what it actually does, but the bottom line is that it requires, or at least it could benefit from having, a RESTful WCF service hosted on both http and https endpoints.

I toyed with the idea of doing the application in Python as it uses some Python code but I decided to stick with what I knew as I wanted to finish it quickly. At any rate, here is the code:

This is simply shown as an example of how it could be done, if you follow it, your end point will be listening on http://<hostname>/store/ and can be invoked by simply navigating to it like this:

http://<hostname>/store?page=url 

In order for the application to listen on https you will need to have a valid certificate on your certificate store. The subject name should match the hostname of the machine running this application and then this should work:

https://<hostname>/store?page=url 

First the interface:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;

namespace WcfJsonRestService
{
    [ServiceContract]
    public interface IStore
    {
        [OperationContract]
        bool Store(string item);
    }

}
Then the class implementing the interface:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;
using System.Configuration;

namespace WcfJsonRestService
{
   
    public class Store : IStore
    {
        [WebInvoke(Method = "GET",
                    ResponseFormat = WebMessageFormat.Json,
                    UriTemplate = "store?page={item}")]
        public bool Store(string item)
        {
            //do stuff here

            return true;
        }

    }
}
And finally a Console application that hosts the service.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography.X509Certificates;
using System.ServiceModel;
using System.ServiceModel.Description;
using System.ServiceProcess;
using System.Text;
using System.Threading.Tasks;

namespace WcfJsonRestService
{
    class Program
    {
        static void Main(string[] args)
        {

            try
            {
                using (ServiceHost host = new ServiceHost(typeof(RESTful)))
                {

                    AddServiceEndPoint(host, "https://{0}/store", true, "change me");
                    AddServiceEndPoint(host, "http://{0}/store", false);

                    host.Open();

                    Console.WriteLine("Service host running......");
                    Console.WriteLine("Press Any key at any time to exit...");

                    Console.Read();

                    host.Close();
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
                Console.Read();
            }


        }

        private static void AddServiceEndPoint(ServiceHost host, string url, bool useSSLTLS, string certSubjectName="")
        {
            string addressHttp = String.Format(url,
                System.Net.Dns.GetHostEntry("").HostName);


            WebHttpBinding binding;

            if (useSSLTLS)
            {

                binding = new WebHttpBinding(WebHttpSecurityMode.Transport);
                binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.None;
                binding.HostNameComparisonMode = HostNameComparisonMode.WeakWildcard;
                binding.CrossDomainScriptAccessEnabled = true;
            }
            else
            {
                binding = new WebHttpBinding(WebHttpSecurityMode.None);
                binding.CrossDomainScriptAccessEnabled = true;
            }

            // You must create an array of URI objects to have a base address.
            Uri uri = new Uri(addressHttp);
            Uri[] baseAddresses = new Uri[] { uri };

            WebHttpBehavior behaviour = new WebHttpBehavior();
            // Add an endpoint to the service. Insert the thumbprint of an X.509 
            // certificate found on your computer. 
            host.AddServiceEndpoint(typeof(IRESTful), binding, uri).EndpointBehaviors.Add(behaviour);

            if (useSSLTLS)
            {
                host.Credentials.ServiceCertificate.SetCertificate(
                    StoreLocation.LocalMachine,
                    StoreName.My,
                    X509FindType.FindBySubjectName,
                    certSubjectName);
            }
        }
    }
}

Alternatively, the WCF service can be hosted by a Windows service. Code behind for windows service here:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.ServiceModel;
using System.ServiceModel.Description;
using System.ServiceProcess;
using System.Text;
using System.Threading.Tasks;
using StoreAndConvert.WCFService;
using System.Security.Cryptography.X509Certificates;
using System.Configuration;


namespace StoreAndConvert.WindowsService
{
    public partial class Store : ServiceBase
    {

        string certSubjectName = string.Empty;

        ServiceHost host;

        public Store()
        {
            InitializeComponent();
        }


        protected override void OnStart(string[] args)
        {
            try
            {
                //Debugger.Launch();
                certSubjectName = ConfigurationManager.AppSettings["CertificateSubjectName"];

                host = new ServiceHost(typeof(StoreUrls));

                AddServiceEndPoint(host, "https://{0}/storeurl", true, certSubjectName);
                AddServiceEndPoint(host, "http://{0}/storeurl", false);

                host.Open();

                Trace.WriteLine("Service host running......");
                Trace.WriteLine("Listening on");

                foreach (ServiceEndpoint sep in host.Description.Endpoints)
                {
                    Trace.WriteLine(string.Format("endpoint: {0} - BindingType: {1}",
                        sep.Address, sep.Binding.Name));
                }
            }
            catch (Exception ex)
            {
                Trace.WriteLine(ex);
            }

        }

        protected override void OnStop()
        {
            try
            {
                if (host != null)
                {
                    host.Close();
                }
            }
            catch (Exception ex)
            {
                Trace.WriteLine(ex);
            }
        }

        private void AddServiceEndPoint(ServiceHost host, string url, bool useSSLTLS, string certSubjectName = "")
        {
            string addressHttp = String.Format(url,
                System.Net.Dns.GetHostEntry("").HostName);

            WebHttpBinding binding;

            if (useSSLTLS)
            {
                binding = new WebHttpBinding(WebHttpSecurityMode.Transport);
                binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.None;
                binding.HostNameComparisonMode = HostNameComparisonMode.WeakWildcard;
                binding.CrossDomainScriptAccessEnabled = true;
            }
            else
            {
                binding = new WebHttpBinding(WebHttpSecurityMode.None);
                binding.CrossDomainScriptAccessEnabled = true;
            }

            // You must create an array of URI objects to have a base address.
            Uri uri = new Uri(addressHttp);
            Uri[] baseAddresses = new Uri[] { uri };

            WebHttpBehavior behaviour = new WebHttpBehavior();
            // Add an endpoint to the service. Insert the thumbprint of an X.509 
            // certificate found on your computer. 
            host.AddServiceEndpoint(typeof(IStoreUrls), binding, uri).EndpointBehaviors.Add(behaviour);

            if (useSSLTLS)
            {
                host.Credentials.ServiceCertificate.SetCertificate(
                    StoreLocation.LocalMachine,
                    StoreName.My,
                    X509FindType.FindBySubjectName,
                    certSubjectName);
            }
        }
    }
}

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