基于 .net core + Ocelot 微服务方式

让大家将需要定义的接口全部以http 接口形式重写定义一遍, 同时客户端调用的时候, 需要将原来熟悉的形如 XXService.YYMethod(args1, args2) 直接使用通过 "."出内部成员,替换为让其直接写 HttpClient.Post("url/XX/YY",”args1=11&args2=22”)的形式访问远程接口,确实是一件十分痛苦的事情.

问题提出

基于以上, 如何通过一种模式来简化这种调用形式, 继而使大家在调用的时候不需要关心该服务是在本地(本地类库依赖)还是远程, 只需要按照常规方式使用即可, 至于是直接使用本地服务还是通过http发送远程请求,这个都交给框架处理.为了方便叙述, 本文假定以销售订单和用户服务为例. 销售订单服务对外提供一个创建订单的接口.订单创建成功后, 调用用户服务更新用户积分.UML参考如下.

问题转化

• 在客户端,通过微服务对外公开的接口,生成接口代理, 即将接口需要的信息[接口名/方法名及该方法需要的参数]包装成http请求向远程服务发起请求.
• 在微服务http接入段, 我们可以定义一个统一的入口,当服务端收到请求后,解析出接口名/方法名及参数信息,并创建对应的实现类,从而执行接口请求,并将返回值通过http返回给客户端.
• 最后,客户端通过类似 AppRuntims.Instance.GetService().SaveOrder(orderInfo) 形式访问远程服务创建订单.
• 数据以json格式传输.

解决方案及实现

为了便于处理,我们定义了一个空接口IApiService,用来标识服务接口.

远程服务客户端代理

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public class RemoteServiceProxy : IApiService {  public string Address { get; set; } //服务地址private ApiActionResult PostHttpRequest(string interfaceId, string methodId, params object[] p)  {  ApiActionResult apiRetult = null;  using (var httpClient = new HttpClient())  {   var param = new ArrayList(); //包装参数     foreach (var t in p)   {   if (t == null)   {    param.Add(null);   }   else   {    var ns = t.GetType().Namespace;    param.Add(ns != null && ns.Equals("System") ? t : JsonConvert.SerializeObject(t));   }   }   var postContentStr = JsonConvert.SerializeObject(param);   HttpContent httpContent = new StringContent(postContentStr);   if (CurrentUserId != Guid.Empty)   {   httpContent.Headers.Add("UserId", CurrentUserId.ToString());   }   httpContent.Headers.Add("EnterpriseId", EnterpriseId.ToString());   httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");     var url = Address.TrimEnd('/') + $"/{interfaceId}/{methodId}";   AppRuntimes.Instance.Loger.Debug($"httpRequest:{url},data:{postContentStr}");     var response = httpClient.PostAsync(url, httpContent).Result; //提交请求     if (!response.IsSuccessStatusCode)   {   AppRuntimes.Instance.Loger.Error($"httpRequest error:{url},statuscode:{response.StatusCode}");   throw new ICVIPException("网络异常或服务响应失败");   }   var responseStr = response.Content.ReadAsStringAsync().Result;   AppRuntimes.Instance.Loger.Debug($"httpRequest response:{responseStr}");     apiRetult = JsonConvert.DeserializeObject(responseStr);  }  if (!apiRetult.IsSuccess)  {   throw new BusinessException(apiRetult.Message ?? "服务请求失败");  }  return apiRetult;  }    //有返回值的方法代理  public T Invoke(string interfaceId, string methodId, params object[] param)  {  T rs = default(T);    var apiRetult = PostHttpRequest(interfaceId, methodId, param);    try  {   if (typeof(T).Namespace == "System")   {   rs = (T)TypeConvertUtil.BasicTypeConvert(typeof(T), apiRetult.Data);   }   else   {   rs = JsonConvert.DeserializeObject(Convert.ToString(apiRetult.Data));   }  }  catch (Exception ex)  {   AppRuntimes.Instance.Loger.Error("数据转化失败", ex);   throw;  }  return rs;  }    //没有返回值的代理  public void InvokeWithoutReturn(string interfaceId, string methodId, params object[] param)  {  PostHttpRequest(interfaceId, methodId, param);  } }

远程服务端http接入段统一入口

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[Route("api/svc/{interfaceId}/{methodId}"), Produces("application/json")] public async Task Process(string interfaceId, string methodId) {  Stopwatch stopwatch = new Stopwatch();  stopwatch.Start();  ApiActionResult result = null;  string reqParam = string.Empty;  try  {  using (var reader = new StreamReader(Request.Body, Encoding.UTF8))  {   reqParam = await reader.ReadToEndAsync();  }  AppRuntimes.Instance.Loger.Debug($"recive client request:api/svc/{interfaceId}/{methodId},data:{reqParam}");    ArrayList param = null;  if (!string.IsNullOrWhiteSpace(reqParam))  {   //解析参数   param = JsonConvert.DeserializeObject(reqParam);  }  //转交本地服务处理中心处理  var data = LocalServiceExector.Exec(interfaceId, methodId, param);  result = ApiActionResult.Success(data);  }  catch BusinessException ex) //业务异常  {  result = ApiActionResult.Error(ex.Message);  }  catch (Exception ex)  {  //业务异常  if (ex.InnerException is BusinessException)  {   result = ApiActionResult.Error(ex.InnerException.Message);  }  else  {   AppRuntimes.Instance.Loger.Error($"调用服务发生异常{interfaceId}-{methodId},data:{reqParam}", ex);   result = ApiActionResult.Fail("服务发生异常");  }  }  finally  {  stopwatch.Stop();  AppRuntimes.Instance.Loger.Debug($"process client request end:api/svc/{interfaceId}/{methodId},耗时[ {stopwatch.ElapsedMilliseconds} ]毫秒");  }  //result.Message = AppRuntimes.Instance.GetCfgVal("ServerName") + " " + result.Message;  result.Message = result.Message;  return result; }

本地服务中心通过接口名和方法名,找出具体的实现类的方法,并使用传递的参数执行,ps:因为涉及到反射获取具体的方法,暂不支持相同参数个数的方法重载.仅支持不同参数个数的方法重载.

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public static object Exec(string interfaceId, string methodId, ArrayList param) {  var svcMethodInfo = GetInstanceAndMethod(interfaceId, methodId, param.Count);  var currentMethodParameters = new ArrayList();    for (var i = 0; i < svcMethodInfo.Paramters.Length; i++)  {  var tempParamter = svcMethodInfo.Paramters[i];    if (param[i] == null)  {   currentMethodParameters.Add(null);  }  else  {   if (!tempParamter.ParameterType.Namespace.Equals("System") || tempParamter.ParameterType.Name == "Byte[]")   {   currentMethodParameters.Add(JsonConvert.DeserializeObject(Convert.ToString(param[i]), tempParamter.ParameterType)   }   else   {   currentMethodParameters.Add(TypeConvertUtil.BasicTypeConvert(tempParamter.ParameterType, param[i]));   }  }  }    return svcMethodInfo.Invoke(currentMethodParameters.ToArray()); }   private static InstanceMethodInfo GetInstanceAndMethod(string interfaceId, string methodId, int paramCount) {  var methodKey = $"{interfaceId}_{methodId}_{paramCount}";  if (methodCache.ContainsKey(methodKey))  {  return methodCache[methodKey];  }  InstanceMethodInfo temp = null;    var svcType = ServiceFactory.GetSvcType(interfaceId, true);  if (svcType == null)  {  throw new ICVIPException($"找不到API接口的服务实现:{interfaceId}");  }  var methods = svcType.GetMethods().Where(t => t.Name == methodId).ToList();  if (methods.IsNullEmpty())  {  throw new BusinessException($"在API接口[{interfaceId}]的服务实现中[{svcType.FullName}]找不到指定的方法:{methodId}");  }  var method = methods.FirstOrDefault(t => t.GetParameters().Length == paramCount);  if (method == null)  {  throw new ICVIPException($"在API接口中[{interfaceId}]的服务实现[{svcType.FullName}]中,方法[{methodId}]参数个数不匹配");  }  var paramtersTypes = method.GetParameters();    object instance = null;  try  {  instance = Activator.CreateInstance(svcType);  }  catch (Exception ex)  {  throw new BusinessException($"在实例化服务[{svcType}]发生异常,请确认其是否包含一个无参的构造函数", ex);  }  temp = new InstanceMethodInfo()  {  Instance = instance,  InstanceType = svcType,  Key = methodKey,  Method = method,  Paramters = paramtersTypes  };  if (!methodCache.ContainsKey(methodKey))  {  lock (_syncAddMethodCacheLocker)  {   if (!methodCache.ContainsKey(methodKey))   {   methodCache.Add(methodKey, temp);   }  }  }  return temp;

服务配置,指示具体的服务的远程地址,当未配置的服务默认为本地服务.

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[  {  "ServiceId": "XZL.Api.IOrderService",  "Address": "http://localhost:8801/api/svc"  },  {  "ServiceId": "XZL.Api.IUserService",  "Address": "http://localhost:8802/api/svc"  } ]

AppRuntime.Instance.GetService()的实现.

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private static List<(string typeName, Type svcType)> svcTypeDic; private static ConcurrentDictionary<string, Object> svcInstance = new ConcurrentDictionary<string, object>();    public static TService GetService()  {  var serviceId = typeof(TService).FullName;    //读取服务配置  var serviceInfo = ServiceConfonfig.Instance.GetServiceInfo(serviceId);  if (serviceInfo == null)  {   return (TService)Activator.CreateInstance(GetSvcType(serviceId));  }  else  {   var rs = GetService(serviceId + (serviceInfo.IsRemote ? "|Remote" : ""), serviceInfo.IsSingle);   if (rs != null && rs is RemoteServiceProxy)   {   var temp = rs as RemoteServiceProxy;   temp.Address = serviceInfo.Address; //指定服务地址   }   return rs;  }  } public static TService GetService(string interfaceId, bool isSingle) {  //服务非单例模式  if (!isSingle)  {  return (TService)Activator.CreateInstance(GetSvcType(interfaceId));  }    object obj = null;  if (svcInstance.TryGetValue(interfaceId, out obj) && obj != null)  {  return (TService)obj;  }  var svcType = GetSvcType(interfaceId);    if (svcType == null)  {  throw new ICVIPException($"系统中未找到[{interfaceId}]的代理类");  }  obj = Activator.CreateInstance(svcType);    svcInstance.TryAdd(interfaceId, obj);  return (TService)obj; }   //获取服务的实现类 public static Type GetSvcType(string interfaceId, bool? isLocal = null) {  if (!_loaded)  {  LoadServiceType();  }  Type rs = null;  var tempKey = interfaceId;    var temp = svcTypeDic.Where(x => x.typeName == tempKey).ToList();    if (temp == null || temp.Count == 0)  {  return rs;  }    if (isLocal.HasValue)  {  if (isLocal.Value)  {   rs = temp.FirstOrDefault(t => !typeof(RemoteServiceProxy).IsAssignableFrom(t.svcType)).svcType;  }  else  {   rs = temp.FirstOrDefault(t => typeof(RemoteServiceProxy).IsAssignableFrom(t.svcType)).svcType;  }  }  else  {  rs = temp[0].svcType;  }  return rs; }

为了性能影响,我们在程序启动的时候可以将当前所有的ApiService类型缓存.

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public static void LoadServiceType()  {  if (_loaded)  {   return;  }  lock (_sync)  {   if (_loaded)   {   return;   }   try   {   svcTypeDic = new List<(string typeName, Type svcType)>();   var path = AppDomain.CurrentDomain.RelativeSearchPath ?? AppDomain.CurrentDomain.BaseDirectory;   var dir = new DirectoryInfo(path);   var files = dir.GetFiles("XZL*.dll");   foreach (var file in files)   {    var types = LoadAssemblyFromFile(file);    svcTypeDic.AddRange(types);   }   _loaded = true;   }   catch   {   _loaded = false;   }  }  }   //加载指定文件中的ApiService实现 private static List<(string typeName, Type svcType)> LoadAssemblyFromFile(FileInfo file) {  var lst = new List<(string typeName, Type svcType)>();  if (file.Extension != ".dll" && file.Extension != ".exe")  {  return lst;  }  try  {  var types = Assembly.Load(file.Name.Substring(0, file.Name.Length - 4))    .GetTypes()    .Where(c => c.IsClass && !c.IsAbstract && c.IsPublic);  foreach (Type type in types)  {   //客户端代理基类   if (type == typeof(RemoteServiceProxy))   {   continue;   }     if (!typeof(IApiService).IsAssignableFrom(type))   {   continue;   }     //绑定现类   lst.Add((type.FullName, type));     foreach (var interfaceType in type.GetInterfaces())   {   if (!typeof(IApiService).IsAssignableFrom(interfaceType))   {    continue;   }  //绑定接口与实际实现类   lst.Add((interfaceType.FullName, type));   }  }  }  catch  {  }    return lst; }

具体api远程服务代理示例

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public class UserServiceProxy : RemoteServiceProxy, IUserService  {  private string serviceId = typeof(IUserService).FullName;    public void IncreaseScore(int userId,int score)  {   return InvokeWithoutReturn(serviceId, nameof(IncreaseScore), userId,score);  }  public UserInfo GetUserById(int userId)  {   return Invoke(serviceId, nameof(GetUserById), userId);  } }

结语

经过以上改造后, 我们便可很方便的通过形如 AppRuntime.Instance.GetService().MethodXX()无感的访问远程服务, 服务是部署在远程还是在本地以dll依赖形式存在,这个便对调用者透明了.无缝的对接上了大家固有习惯.