Wcf通讯基础框架方案（二）——集中配置
从这次开始在几个方面简单阐述一下实现，集中配置是这个框架很大的一个目的，首先在数据库中会有这么一些表：
其实可以看到这些表的结构，应该是和<system.serviceModel>配置节点中的层次有对应的
1） Service表描述的是服务，主要保存服务行为以及服务的配置。在这里，ServiceConfig是框架内用到的配置，比如各种日志是否要记录等等。服务对应到服务的集群，集群公开一个地址，客户端访问这个地址，也就是一个负载均衡的虚拟IP地址。
2） 一个Service可以有多个ServiceEndpoint，ServiceEndpoint中定义了契约的版本，类型和行为，以及涉及到地址的端口、端点名字等。客户端和服务端部署的服务契约版本号不一定是一致的，在选择端点的时候优先选择匹配的版本。
3） 一个ServiceEndpoint对应一个Binding，一个Binding也可以对应多个ServiceEndpoint。Binding表中记录了绑定类型、优先级、以及协议前缀和绑定的Xml配置。在选择服务端点的时候会优先选择优先级别比较高的绑定。
4） ClientAccess表主要用于限制哪些客户端机器可以访问哪些服务集群。
5） ClientEndpoint表主要用于设置ClientEndpoint的行为Xml（和ServiceEndpoint行为Xml不能保持一致，对于绑定客户端和服务端是公用的）。
上述这些逻辑可以体现在配置服务的两个方法实现中：
public WcfService GetWcfService(string serviceType, string serviceContractVersion, string machineName) { using (WcfConfigDataContext data = new WcfConfigDataContext()) { var wcfService = (from service in data.Services where service.ServiceType == serviceType && (service.ServerMachineName == "*" || service.ServerMachineName == machineName) select new WcfService { ServiceType = serviceType, ServiceBehaviorXml = service.ServiceBehaviorXml.ToString(), Endpoints = (from ep in data.ServiceEndpoints where ep.ServiceType == serviceType && ep.ServiceContractVersion == serviceContractVersion select new WcfServiceEndpoint { EndpointBehaviorXml = ep.ServiceEndpointBehaviorXml.ToString(), EndpointBindingName = ep.ServiceEndpointBindingName, EndpointName = ep.ServiceEndpointName, EndpointPort = ep.ServiceEndpointPort, ServiceContractType = ep.ServiceContractType, EndpointBindingType = ep.Binding.BindingType, EndpointBindingXml = ep.Binding.BindingXml.ToString(), EndpointProtocol = ep.Binding.BindingProtocol }).ToArray() }).SingleOrDefault(); return wcfService; } } public WcfClientEndpoint GetWcfClientEndpoint(string serviceContractType, string serviceContractVersion, string machineName) { using (WcfConfigDataContext data = new WcfConfigDataContext()) { var wcfClientEndpoint = (from ep in (data.ServiceEndpoints .Where(s => s.ServiceContractType == serviceContractType).ToList()) where (ep.ServiceContractVersion == "" || float.Parse(ep.ServiceContractVersion) >= float.Parse(serviceContractVersion)) orderby ep.ServiceContractVersion ascending, ep.Binding.BindingPriority descending select new WcfClientEndpoint { EndpointName = ep.ServiceEndpointName, EndpointPort = ep.ServiceEndpointPort, ServiceContractType = ep.ServiceContractType, EndpointBindingType = ep.Binding.BindingType, EndpointBindingXml = ep.Binding.BindingXml.ToString(), EndpointProtocol = ep.Binding.BindingProtocol, EndpointAddress = ep.Service.ServerFarm.ServerFarmAddress, ServerFarmName = ep.Service.ServerFarmName, }).FirstOrDefault(); var accessableFarmNames = data.ClientAccesses.Where(acc => acc.ClientMachineName == "*" || acc.ClientMachineName == machineName).Select(a => a.AccessServerFarmName).ToList(); if (!accessableFarmNames.Contains("*") && !accessableFarmNames.Contains(wcfClientEndpoint.ServerFarmName)) return null; var query = (from ce in data.ClientEndpoints where ce.ServiceContractType == wcfClientEndpoint.ServiceContractType select ce.ClientEndpointBehaviorXml).FirstOrDefault(); wcfClientEndpoint.EndpointBehaviorXml = query != null ? query.ToString() : ""; return wcfClientEndpoint; } }
有了配置，那么客户端和服务端怎么应用上这些ABC呢？先来看看服务端：
public class WcfServiceHostFactory : ServiceHostFactory { protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses) { return CreateServiceHost(serviceType); } public static ServiceHost CreateServiceHost<T>() { return CreateServiceHost(typeof(T)); } public static ServiceHost CreateServiceHost(Type serviceType) { string typeName = serviceType.FullName; var serviceHost = new ServiceHost(serviceType); if (!typeof(IWcfConfigService).IsAssignableFrom(serviceType) && !typeof(IWcfLogService).IsAssignableFrom(serviceType)) { if (serviceHost.Description.Behaviors.Find<ServiceErrorBehavior>() == null) serviceHost.Description.Behaviors.Add(new ServiceErrorBehavior()); if (serviceHost.Description.Behaviors.Find<ActionInterceptBehavior>() == null) serviceHost.Description.Behaviors.Add(new ActionInterceptBehavior()); if (serviceHost.Description.Behaviors.Find<UnityServiceBehavior>() == null) serviceHost.Description.Behaviors.Add(new UnityServiceBehavior()); serviceHost.Description.Endpoints.Clear(); var wcfService = GetWcfServiceConfiguration(serviceType); if (wcfService == null) throw new Exception("Can not locate any Wcf service, please check metadata config!"); var bindingCache = new Dictionary<string, Binding>(); foreach (var ep in wcfService.Endpoints) { string address = ConfigHelper.CreateAddress( ep.EndpointProtocol, Environment.MachineName, ep.EndpointPort, ep.EndpointName); Binding binding; if (!bindingCache.TryGetValue(address, out binding)) { binding = ConfigHelper.CreateBinding(ep.EndpointBindingType, ep.EndpointBindingXml); bindingCache[address] = binding; } serviceHost.AddServiceEndpoint(ep.ServiceContractType, binding, address); if (!string.IsNullOrEmpty(ep.EndpointBehaviorXml)) { AddEndPointBehavior(serviceHost.Description.Endpoints.Last(), ep.EndpointBehaviorXml); } } foreach (var ep in serviceHost.Description.Endpoints) { ep.Behaviors.Add(new MessageInspectorEndpointBehavior()); } if (!string.IsNullOrEmpty(wcfService.ServiceBehaviorXml)) AddServiceBehavior(serviceHost, wcfService.ServiceBehaviorXml); WcfLogManager.InitLog(serviceType, LogType.Service); serviceHost.Opened += (sender, o) => { if (WcfLogManager.Current(serviceType).StartInfo.Server.Enabled) { var log = WcfLogProvider.GetServerStartInfo(serviceType.FullName, "WcfServiceHostFactory.CreateServiceHost", wcfService); WcfServiceLocator.GetLogService().LogWithoutException(log); } }; } return serviceHost; } private static void AddEndPointBehavior(ServiceEndpoint serviceEndpoint, string behavior) { var doc = new XmlDocument(); doc.LoadXml(behavior); var endpointBehaviorElement = new EndpointBehaviorElement(); ConfigHelper.Deserialize(doc.OuterXml, endpointBehaviorElement); foreach (var item in endpointBehaviorElement) { ConfigHelper.SetBehavior(serviceEndpoint.Behaviors, item); } } private static void AddServiceBehavior(ServiceHost serviceHost, string behavior) { var doc = new XmlDocument(); doc.LoadXml(behavior); var serviceBehaviorElement = new ServiceBehaviorElement(); ConfigHelper.Deserialize(doc.OuterXml, serviceBehaviorElement); foreach (var item in serviceBehaviorElement) { ConfigHelper.SetBehavior(serviceHost.Description.Behaviors, item); } } private static WcfService GetWcfServiceConfiguration(Type serviceType) { var version = serviceType.GetInterfaces().First().Assembly.GetName().Version; try { using (var scf = WcfServiceClientFactory.CreateServiceClient<IWcfConfigService>()) { return scf.Channel.GetWcfService(serviceType.FullName, version.Major + "." + version.Minor, Environment.MachineName); } } catch (Exception ex) { LocalLogService.Log(ex.ToString()); throw new Exception("Can not get service metadata, error message is " + ex.Message); } } } }
其实没什么复杂的，无非是应用配置，但是这里注意到几点：
1） 在我们自己的WcfServiceHostFactory里面，我们除了从配置服务读取配置，并且应用之外，还加入了框架本身需要的一些扩展的ServiceBehavior。如果以后有其它需要扩展的，客户端和服务端也只需要更新一下框架的dll即可。
2） 此外，可以看到在服务启动的时候，根据开关，加上了StartInfo的日志，有关日志部分更详细的东西会在以后介绍。这也是框架的另外一个好处，内置大量的横切关注点的考虑。
再来看看客户端的代码，其实和服务端差不多：
private static ChannelFactory<T> CreateChannelFactory<T>(WcfClientEndpoint endpoint) { if (endpoint == null) throw new Exception("Can not locate any endpoint, please check metadata config!"); var binding = ConfigHelper.CreateBinding(endpoint.EndpointBindingType, endpoint.EndpointBindingXml); if (binding is NetNamedPipeBinding) endpoint.EndpointAddress = "localhost"; var address = ConfigHelper.CreateAddress(endpoint.EndpointProtocol, endpoint.EndpointAddress, endpoint.EndpointPort, endpoint.EndpointName); var factory = new ChannelFactory<T>(binding, address); factory.Endpoint.Behaviors.Add(new MessageInspectorEndpointBehavior()); if (!string.IsNullOrEmpty(endpoint.EndpointBehaviorXml)) AddEndpointBehavior(factory, endpoint.EndpointBehaviorXml); return factory; } private static void AddEndpointBehavior(ChannelFactory factory, string behaviorXml) { var doc = new XmlDocument(); doc.LoadXml(behaviorXml); var endpointBehaviorElement = new EndpointBehaviorElement(); ConfigHelper.Deserialize(doc.OuterXml, endpointBehaviorElement); foreach (var item in endpointBehaviorElement) { ConfigHelper.SetBehavior(factory.Endpoint.Behaviors, item); } } private static WcfClientEndpoint GetWcfClientEndpointConfiguration(Type serviceContractType) { var version = serviceContractType.Assembly.GetName().Version; var versionstring = version.Major + "." + version.Minor; try { using (var scf = WcfServiceClientFactory.CreateServiceClient<IWcfConfigService>()) { return scf.Channel.GetWcfClientEndpoint(serviceContractType.FullName, versionstring, WcfLogProvider.MachineName); } } catch (Exception ex) { LocalLogService.Log(ex.ToString()); throw new Exception("Can not get client metadata, error message is " + ex.Message); } } internal static WcfChannelWrapper<T> CreateServiceClient<T>() where T : class { string typeName = typeof(T).FullName; ChannelFactory cf; if (!channelFactoryCache.TryGetValue(typeName, out cf)) { lock (cacheLocker) { if (!channelFactoryCache.TryGetValue(typeName, out cf)) { if (typeof(T) == typeof(IWcfConfigService)) { var configServiceAddress = ConfigurationManager.AppSettings[WCFCONFIGSERVICE_ADDRESS_KEY]; if (string.IsNullOrEmpty(configServiceAddress)) throw new Exception("Please set " + WCFCONFIGSERVICE_ADDRESS_KEY + "appSettings in your config!"); var binding = new NetTcpBinding(); binding.Security.Mode = SecurityMode.None; var address = string.Format("net.tcp://{0}/WcfConfigService", configServiceAddress); cf = new ChannelFactory<IWcfConfigService>(binding, address); } else if (typeof(T) == typeof(IWcfLogService)) { var logServiceAddress = ConfigurationManager.AppSettings[WCFLOGSERVICE_ADDRESS_KEY]; if (string.IsNullOrEmpty(logServiceAddress)) throw new Exception("Please set " + WCFLOGSERVICE_ADDRESS_KEY + "appSettings in your config!"); var elements = new List<BindingElement>(); elements.Add(new BinaryMessageEncodingBindingElement()); elements.Add(new TcpTransportBindingElement()); var binding = new CustomBinding(elements); var address = string.Format("net.tcp://{0}/WcfLogService", logServiceAddress); cf = new ChannelFactory<IWcfLogService>(binding, address); } else { if (redisSubThread == null) { CreateRedisSubThread(); } var endpoint = GetWcfClientEndpointConfiguration(typeof(T)); cf = CreateChannelFactory<T>(endpoint); WcfLogManager.InitLog<T>(LogType.Client); if (WcfLogManager.Current<T>().StartInfo.Client.Enabled) { var log = WcfLogProvider.GetClientStartInfo(typeof(T).FullName, "WcfServiceClientFactory.CreateServiceClient", endpoint); WcfServiceLocator.GetLogService().LogWithoutException(log); } } channelFactoryCache[typeName] = cf; } } } return new WcfChannelWrapper<T>((cf as ChannelFactory<T>).CreateChannel()); }
在这里要解释几点：
1） 客户端会根据契约的类型来缓存信道工厂，每一次使用了信道之后都会正确关闭，这个是通过WcfChannelWrapper保证的。更多有关客户端的内容会在下次介绍，本次只是介绍配置集中。
2） 对于日志服务和配置服务的配置，没有定义在数据库中，而是写死的，只有地址是可以配置的配置文件中的。日志服务和配置服务不但是业务的客户端需要使用，业务的服务端也是需要使用的，所以不管是客户端还是服务端都需要配置两个基础服务的地址。虽然是写死在配置文件中的，但是一般生产环境会配置一个虚拟IP地址，把这2个服务做成负载均衡的服务，地址一般不会变动。
3） 和服务端一样，也加上了框架本身需要的一些扩展，比如MessageInspectorEndpointBehavior。
最后，配置集中的好处：
1） 可以灵活修改各种服务的行为、端点的行为，统一管理地址。修改之后，可以通过发布订阅机制通知到客户端和服务端。
2） 可以做一些版本控制的路由、权限控制、绑定优先级控制等等。
3） 可以基于这些元数据做一些监控等。