Start ServiceHosts for all configured Services

Important Update: The originally presented code only works if the service is defined in the same assembly which hosts the service (because the name="" attribute in <service> may not contain the assembly name of the service). See at the end of the article for a slightly different version which works in all cases --- but which involves adding a second config file.

As WCF has reached RC1 stage, I find myself cleaning up a few bits of older WCF code. While playing around with it, I always found myself having to start more and more ServiceHosts for different configurations. The following snippet iterates over all <service> entries in configuration/system.serviceModel and opens a ServiceHost for each of them.

Update: Added code to close all services.

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Configuration;
using System.ServiceModel.Configuration;
using System.ServiceModel;

public class ServiceHostGroup
{
    static List<ServiceHost> _hosts = new List<ServiceHost>();

    private static void OpenHost(Type t)
    {
        ServiceHost hst = new ServiceHost(t);
        hst.Open();
        _hosts.Add(hst);
    }

    public static void StartAllConfiguredServices()
    {
        Configuration conf =
          ConfigurationManager.OpenExeConfiguration(Assembly.GetEntryAssembly().Location);

        ServiceModelSectionGroup svcmod =
          (ServiceModelSectionGroup)conf.GetSectionGroup("system.serviceModel");
        foreach (ServiceElement el in svcmod.Services.Services)
        {
            Type svcType = Type.GetType(el.Name);
            if (svcType == null)
              throw new Exception("Invalid Service Type " + el.Name + " in configuration file.");
            OpenHost(svcType);
        }

    }


    public static void CloseAllServices()
    {
        foreach (ServiceHost hst in _hosts)
        {
            hst.Close();
        }
    }
}

As mentioned above, I have in the meantime learned (after long and hard fighting against the "this service has no non-metadata endpoints"-exception), that the name="" attribute in <service> must not contain an assembly name. I guess I have been too used to Remoting configuration files after all ;-). To still get dynamic service configuration without code changes, I've added a second configuration file called services.xml and changed the code for ServiceHostGroup to the following:

Services.XML:

<configuredServices>
  <service type="ServiceImplementation.ArticleService, ServiceImplementation" />
</configuredServices>

ServiceHostBase.cs:

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Configuration;
using System.ServiceModel.Configuration;
using System.ServiceModel;
using System.Xml;
using System.Xml.Serialization;
using System.IO;

public class ServiceHostGroup
{
  static List<ServiceHost> _hosts = new List<ServiceHost>();

  private static void OpenHost(Type t)
  {
    ServiceHost hst = new ServiceHost(t);
    Type ty = hst.Description.ServiceType;
    hst.Open();
    _hosts.Add(hst);
  }

  public static void StartAllConfiguredServices()
  {
    ConfiguredServices services = ConfiguredServices.LoadFromFile("services.xml");

    foreach (ConfiguredService svc in services.Services)
    {
      Type svcType = Type.GetType(svc.Type);
      if (svcType == null) throw new Exception("Invalid Service Type " + svc.Type + " in configuration file.");
      OpenHost(svcType);
    }
  }

  public static void CloseAllServices()
  {
    foreach (ServiceHost hst in _hosts)
    {
      hst.Close();
    }
  }
}

[XmlRoot("configuredServices")]
public class ConfiguredServices
{
  public static ConfiguredServices LoadFromFile(string filename)
  {
    if (!File.Exists(filename)) return new ConfiguredServices();

    XmlSerializer ser = new XmlSerializer(typeof(ConfiguredServices));
    using (FileStream fs = File.OpenRead(filename))
    {
      return (ConfiguredServices) ser.Deserialize(fs);
    }
  }

  [XmlElement("service", typeof(ConfiguredService))]
  public List<ConfiguredService> Services = new List<ConfiguredService>();
}

public class ConfiguredService
{
  [XmlAttribute("type")]
  public string Type;
}

Comments

[Nicholas Paldino [.NET/C# MVP]]

While services will more than likely have the same lifetime as an app-domain, they are in no way required to live for the life of the app-domain that they are in. You should expose a way to shut down a particular service as well.

[Ingo Rammer]

Absolutely. It just appears to me that, whenever you want to start/stop services on demand, you will quite likely have a need for more fine grained startup/shutdown behavior (only starting/stopping a subset of them depending on your runtime conditions). In this case, I would rely on ServiceHost as it exists today. Other than that, a CloseAllService() would be as simple as public static void CloseAllServices() { foreach (ServiceHost hst in _hosts) { hst.Close(); } } Cheers, -Ingo

[Ujin]

Absolutely. It just appears to me that, whenever you want to start/stop services on demand, you will quite likely have a need for more fine grained startup/shutdown a href=http://www.dornfall.combehavior/a