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基于.NET Core 微服务的另类实现
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转自：谢中涞
cnblogs.com/xie-zhonglai/p/netcore_micro_svc.html
基于.NET Core 的微服务,网上很多介绍都是千篇一律基于类似WebAPI,通过http请求形式进行访问,但这并不符合大家使用习惯。
如何像形如[ GetService<IOrderService>().SaveOrder(orderInfo)]的方式, 调用远程的服务,如果你正在为此苦恼, 本文或许是一种参考。
一、背景
原项目基于传统三层模式组织代码逻辑,随着时间的推移,项目内各模块逻辑互相交织,互相依赖,维护起来较为困难.为此我们需要引入一种新的机制来尝试改变这个现状,在考察了 Java spring cloud/doubbo, c# wcf/webapi/asp.net core 等一些微服务框架后,我们最终选择了基于 .net core + Ocelot 微服务方式. 经过讨论大家最终期望的项目结果大致如下所示.
但原项目团队成员已经习惯了基于接口服务的这种编码形式, 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.
二、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.
三、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<IOrderService>().SaveOrder(orderInfo) 形式访问远程服务创建订单.
数据以json格式传输.
四、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
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<ApiActionResult>(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<T>(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<T>(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);
}
}3、远程服务端http接入段统一入口
[Route("api/svc/{interfaceId}/{methodId}"), Produces("application/json")]
public async Task<ApiActionResult> 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($"recive client request:api/svc/{interfaceId}/{methodId},data:{reqParam}");
ArrayList param = null;
if (!string.IsNullOrWhiteSpace(reqParam))
{
//解析参数
param = JsonConvert.DeserializeObject<ArrayList>(reqParam);
}
//转交本地服务处理中心处理
var data = LocalServiceExector.Exec(interfaceId, methodId, param);
result = ApiActionResult.Success(data);
}
catch BusinessException ex) //业务异常
{
result = ApiActionResult.Error(ex.Message);
}
catch (Exception ex)
{
//业务异常
if (ex.InnerException is BusinessException)
{
result = ApiActionResult.Error(ex.InnerException.Message);
}
else
{
AppRuntimes.Instance.Loger.Error($"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;
}4、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.
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($"在实例化服务[{svcType}]发生异常,请确认其是否包含一个无参的构造函数", ex);
}
temp = new InstanceMethodInfo()
{
Instance = instance,
InstanceType = svcType,
Key = methodKey,
Method = method,
Paramters = paramtersTypes
};
if (!methodCache.ContainsKey(methodKey))
{
lock (_syncAddMethodCacheLocker)
{
if (!methodCache.ContainsKey(methodKey))
{
methodCache.Add(methodKey, temp);
}
}
}
return temp;5、服务配置,指示具体的服务的远程地址,当未配置的服务默认为本地服务.
[
{
"ServiceId": "XZL.Api.IOrderService",
"Address": "http://localhost:8801/api/svc"
},
{
"ServiceId": "XZL.Api.IUserService",
"Address": "http://localhost:8802/api/svc"
}
]6、AppRuntime.Instance.GetService<TService>()的实现.
private static List<(string typeName, Type svcType)> svcTypeDic;
private static ConcurrentDictionary<string, Object> svcInstance = new ConcurrentDictionary<string, object>();
public static TService GetService<TService>()
{
var serviceId = typeof(TService).FullName;
//读取服务配置
var serviceInfo = ServiceConfonfig.Instance.GetServiceInfo(serviceId);
if (serviceInfo == null)
{
return (TService)Activator.CreateInstance(GetSvcType(serviceId));
}
else
{
var rs = GetService<TService>(serviceId + (serviceInfo.IsRemote ? "|Remote" : ""), serviceInfo.IsSingle);
if (rs != null && rs is RemoteServiceProxy)
{
var temp = rs as RemoteServiceProxy;
temp.Address = serviceInfo.Address; //指定服务地址
}
return rs;
}
}
public static TService GetService<TService>(string interfaceId, bool isSingle)
{
//服务非单例模式
if (!isSingle)
{
return (TService)Activator.CreateInstance(GetSvcType(interfaceId));
}
object obj = null;
if (svcInstance.TryGetValue(interfaceId, out obj) && obj != null)
{
return (TService)obj;
}
var svcType = GetSvcType(interfaceId);
if (svcType == null)
{
throw new ICVIPException($"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;
}7、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.
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;
}8、具体api远程服务代理示例
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<UserInfo >(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<TService>().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.
PS: 但是此番改造后, 遗留下来了另外一个问题: 客户端调用远程服务,需要手动创建一个服务代理( 从 RemoteServiceProxy 继承),虽然每个代理很方便写,只是文中提到的简单两句话,但终究显得繁琐, 是否有一种方式能够根据远程api接口动态的生成这个客户端代理呢? 答案是肯定的,因本文较长了,留在下篇再续.
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