add Gateway middleware

src/DotNetCore.CAP/CAP.AppBuilderExtensions.cs

 using System;
 using DotNetCore.CAP;
+using DotNetCore.CAP.Dashboard.GatewayProxy.Request.Middleware;
+using DotNetCore.CAP.Dashboard.GatewayProxy.Requester.Middleware;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -49,7 +51,13 @@ namespace Microsoft.AspNetCore.Builder
                 throw new InvalidOperationException("Add Cap must be called on the service collection.");
             }
 
-            app.Map(new PathString(pathMatch), x => x.UseMiddleware<DashboardMiddleware>());
+            app.Map(new PathString(pathMatch), x =>
+            {
+                x.UseDownstreamRequestInitialiser();
+                x.UseHttpRequestBuilderMiddleware();
+                x.UseHttpRequesterMiddleware();
+                x.UseMiddleware<DashboardMiddleware>();
+            });
 
             return app;
         }

src/DotNetCore.CAP/Dashboard/CAP.DashboardOptionsExtensions.cs

@@ -5,7 +5,8 @@ using System.Text;
 namespace DotNetCore.CAP
 {
     using DotNetCore.CAP.Dashboard;
-    using DotNetCore.CAP.NodeDiscovery;
+    using DotNetCore.CAP.Dashboard.GatewayProxy;
+    using DotNetCore.CAP.Dashboard.GatewayProxy.Requester;
     using Microsoft.Extensions.DependencyInjection;
 
     internal sealed class DashboardOptionsExtension : ICapOptionsExtension
@@ -23,6 +24,10 @@ namespace DotNetCore.CAP
             _options?.Invoke(dashboardOptions);
             services.AddSingleton(dashboardOptions); 
             services.AddSingleton(DashboardRoutes.Routes);          
+            services.AddSingleton<IHttpRequester, HttpClientHttpRequester>();
+            services.AddSingleton<IHttpClientCache, MemoryHttpClientCache>();
+
+            services.AddScoped<IRequestScopedDataRepository, HttpDataRepository>();
         }
     }
 }

src/DotNetCore.CAP/Dashboard/GatewayProxy/DownstreamUrl.cs

+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy
+{
+    public class DownstreamUrl
+    {
+        public DownstreamUrl(string value)
+        {
+            Value = value;
+        }
+
+        public string Value { get; private set; }
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/GatewayProxyMiddleware.cs

+using System.Collections.Generic;
+using System.Net.Http;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy
+{
+    public abstract class GatewayProxyMiddleware
+    {
+        private readonly IRequestScopedDataRepository _requestScopedDataRepository;
+
+        protected GatewayProxyMiddleware(IRequestScopedDataRepository requestScopedDataRepository)
+        {
+            _requestScopedDataRepository = requestScopedDataRepository;
+            MiddlewareName = this.GetType().Name;
+        }
+
+        public string MiddlewareName { get; }
+
+        //public DownstreamRoute DownstreamRoute => _requestScopedDataRepository.Get<DownstreamRoute>("DownstreamRoute");
+
+        public HttpRequestMessage Request => _requestScopedDataRepository.Get<HttpRequestMessage>("Request");
+
+        public HttpRequestMessage DownstreamRequest => _requestScopedDataRepository.Get<HttpRequestMessage>("DownstreamRequest");
+
+        public HttpResponseMessage HttpResponseMessage => _requestScopedDataRepository.Get<HttpResponseMessage>("HttpResponseMessage");
+
+        public void SetUpstreamRequestForThisRequest(HttpRequestMessage request)
+        {
+            _requestScopedDataRepository.Add("Request", request);
+        }
+
+        public void SetDownstreamRequest(HttpRequestMessage request)
+        {
+            _requestScopedDataRepository.Add("DownstreamRequest", request);
+        }
+
+        public void SetHttpResponseMessageThisRequest(HttpResponseMessage responseMessage)
+        {
+            _requestScopedDataRepository.Add("HttpResponseMessage", responseMessage);
+        }
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/HostAndPort.cs

+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy
+{
+    public class HostAndPort
+    {
+        public HostAndPort(string downstreamHost, int downstreamPort)
+        {
+            DownstreamHost = downstreamHost?.Trim('/');
+            DownstreamPort = downstreamPort;
+        }
+
+        public string DownstreamHost { get; private set; }
+        public int DownstreamPort { get; private set; }
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/HttpDataRepository.cs

+using System;
+using Microsoft.AspNetCore.Http;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy
+{
+    public class HttpDataRepository : IRequestScopedDataRepository
+    {
+        private readonly IHttpContextAccessor _httpContextAccessor;
+
+        public HttpDataRepository(IHttpContextAccessor httpContextAccessor)
+        {
+            _httpContextAccessor = httpContextAccessor;
+        }
+
+        public void Add<T>(string key, T value)
+        {
+            _httpContextAccessor.HttpContext.Items.Add(key, value);
+        }
+
+        public T Get<T>(string key)
+        {
+            object obj;
+
+            if (_httpContextAccessor.HttpContext.Items.TryGetValue(key, out obj))
+            {
+                return (T)obj;
+            }
+            throw new Exception($"Unable to find data for key: {key}");
+        }
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/IRequestScopedDataRepository.cs

+using System.Collections.Generic;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy
+{
+    public interface IRequestScopedDataRepository
+    {
+       void  Add<T>(string key, T value);
+        T Get<T>(string key);
+    }
+}
\ No newline at end of file

src/DotNetCore.CAP/Dashboard/GatewayProxy/Request/Mapper/IRequestMapper.cs

+namespace DotNetCore.CAP.Dashboard.GatewayProxy
+{
+    using System.Net.Http;
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Http;
+
+    public interface IRequestMapper
+    {
+        Task<HttpRequestMessage> Map(HttpRequest request);
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/Request/Mapper/RequestMapper.cs

+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net.Http;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Primitives;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy
+{
+    public class RequestMapper : IRequestMapper
+    {
+        private readonly string[] _unsupportedHeaders = { "host" };
+        private const string SchemeDelimiter = "://";
+
+        public async Task<HttpRequestMessage> Map(HttpRequest request)
+        {
+            try
+            {
+                var requestMessage = new HttpRequestMessage()
+                {
+                    Content = await MapContent(request),
+                    Method = MapMethod(request),
+                    RequestUri = MapUri(request)
+                };
+
+                MapHeaders(request, requestMessage);
+
+                return requestMessage;
+            }
+            catch (Exception ex)
+            {
+                throw new Exception($"Error when parsing incoming request, exception: {ex.Message}");
+            }
+        }
+
+        private async Task<HttpContent> MapContent(HttpRequest request)
+        {
+            if (request.Body == null)
+            {
+                return null;
+            }
+
+            var content = new ByteArrayContent(await ToByteArray(request.Body));
+
+            content.Headers.TryAddWithoutValidation("Content-Type", new[] {request.ContentType});
+
+            return content;
+        }
+
+        private HttpMethod MapMethod(HttpRequest request)
+        {
+            return new HttpMethod(request.Method);
+        }
+
+        private Uri MapUri(HttpRequest request)
+        {
+            return new Uri(GetEncodedUrl(request));
+        }
+
+        private void MapHeaders(HttpRequest request, HttpRequestMessage requestMessage)
+        {
+            foreach (var header in request.Headers)
+            {
+                //todo get rid of if..
+                if (IsSupportedHeader(header))
+                {
+                    requestMessage.Headers.TryAddWithoutValidation(header.Key, header.Value.ToArray());
+                }
+            }
+        }
+
+        private async Task<byte[]> ToByteArray(Stream stream)
+        {
+            using (stream)
+            {
+                using (var memStream = new MemoryStream())
+                {
+                    await stream.CopyToAsync(memStream);
+                    return memStream.ToArray();
+                }
+            }
+        }
+
+        private bool IsSupportedHeader(KeyValuePair<string, StringValues> header)
+        {
+            return !_unsupportedHeaders.Contains(header.Key.ToLower());
+        }
+
+
+        /// <summary>
+        /// Combines the given URI components into a string that is properly encoded for use in HTTP headers.
+        /// Note that unicode in the HostString will be encoded as punycode.
+        /// </summary>
+        /// <param name="scheme">http, https, etc.</param>
+        /// <param name="host">The host portion of the uri normally included in the Host header. This may include the port.</param>
+        /// <param name="pathBase">The first portion of the request path associated with application root.</param>
+        /// <param name="path">The portion of the request path that identifies the requested resource.</param>
+        /// <param name="query">The query, if any.</param>
+        /// <param name="fragment">The fragment, if any.</param>
+        /// <returns></returns>
+        public string BuildAbsolute(
+            string scheme,
+            HostString host,
+            PathString pathBase = new PathString(),
+            PathString path = new PathString(),
+            QueryString query = new QueryString(),
+            FragmentString fragment = new FragmentString())
+        {
+            if (scheme == null)
+            {
+                throw new ArgumentNullException(nameof(scheme));
+            }
+
+            var combinedPath = (pathBase.HasValue || path.HasValue) ? (pathBase + path).ToString() : "/";
+
+            var encodedHost = host.ToString();
+            var encodedQuery = query.ToString();
+            var encodedFragment = fragment.ToString();
+
+            // PERF: Calculate string length to allocate correct buffer size for StringBuilder.
+            var length = scheme.Length + SchemeDelimiter.Length + encodedHost.Length
+                + combinedPath.Length + encodedQuery.Length + encodedFragment.Length;
+
+            return new StringBuilder(length)
+                .Append(scheme)
+                .Append(SchemeDelimiter)
+                .Append(encodedHost)
+                .Append(combinedPath)
+                .Append(encodedQuery)
+                .Append(encodedFragment)
+                .ToString();
+        }
+
+        /// <summary>
+        /// Returns the combined components of the request URL in a fully escaped form suitable for use in HTTP headers
+        /// and other HTTP operations.
+        /// </summary>
+        /// <param name="request">The request to assemble the uri pieces from.</param>
+        /// <returns></returns>
+        public string GetEncodedUrl(HttpRequest request)
+        {
+            return BuildAbsolute(request.Scheme, request.Host, request.PathBase, request.Path, request.QueryString);
+        }
+    }
+}
+

src/DotNetCore.CAP/Dashboard/GatewayProxy/Request/Middleware/DownstreamRequestInitialiserMiddleware.cs

+namespace DotNetCore.CAP.Dashboard.GatewayProxy
+{
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Http;
+    using Microsoft.Extensions.Logging;
+
+    public class DownstreamRequestInitialiserMiddleware : GatewayProxyMiddleware
+    {
+        private readonly RequestDelegate _next;
+        private readonly ILogger _logger;
+        private readonly IRequestMapper _requestMapper;
+
+        public DownstreamRequestInitialiserMiddleware(RequestDelegate next,
+            ILoggerFactory loggerFactory,
+            IRequestScopedDataRepository requestScopedDataRepository,
+            IRequestMapper requestMapper)
+            :base(requestScopedDataRepository)
+        {
+            _next = next;
+            _logger = loggerFactory.CreateLogger<DownstreamRequestInitialiserMiddleware>();
+            _requestMapper = requestMapper;
+        }
+
+        public async Task Invoke(HttpContext context)
+        {
+            _logger.LogDebug("started calling request builder middleware");
+
+            var downstreamRequest = await _requestMapper.Map(context.Request);
+            
+            SetDownstreamRequest(downstreamRequest);
+
+            _logger.LogDebug("calling next middleware");
+
+            await _next.Invoke(context);
+
+            _logger.LogDebug("succesfully called next middleware");
+        }
+    }
+}
\ No newline at end of file

src/DotNetCore.CAP/Dashboard/GatewayProxy/Request/Middleware/HttpRequestBuilderMiddleware.cs

+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy
+{
+    public class HttpRequestBuilderMiddleware : GatewayProxyMiddleware
+    {
+        private readonly RequestDelegate _next;
+        private readonly ILogger _logger;
+
+        public HttpRequestBuilderMiddleware(RequestDelegate next,
+            ILoggerFactory loggerFactory,
+            IRequestScopedDataRepository requestScopedDataRepository )
+            :base(requestScopedDataRepository)
+        {
+            _next = next;
+            _logger = loggerFactory.CreateLogger<HttpRequestBuilderMiddleware>();
+        }
+
+        public async Task Invoke(HttpContext context)
+        {
+            _logger.LogDebug("started calling request builder middleware");
+ 
+            _logger.LogDebug("setting upstream request");
+
+            SetUpstreamRequestForThisRequest(DownstreamRequest);
+
+            _logger.LogDebug("calling next middleware");
+
+            await _next.Invoke(context);
+
+            _logger.LogDebug("succesfully called next middleware");
+        }
+    }
+}
\ No newline at end of file

src/DotNetCore.CAP/Dashboard/GatewayProxy/Request/Middleware/HttpRequestBuilderMiddlewareExtensions.cs

+using Microsoft.AspNetCore.Builder;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy.Request.Middleware
+{
+    public static class HttpRequestBuilderMiddlewareExtensions
+    {
+        public static IApplicationBuilder UseHttpRequestBuilderMiddleware(this IApplicationBuilder builder)
+        {
+            return builder.UseMiddleware<HttpRequestBuilderMiddleware>();
+        }
+
+        public static IApplicationBuilder UseDownstreamRequestInitialiser(this IApplicationBuilder builder)
+        {
+            return builder.UseMiddleware<DownstreamRequestInitialiserMiddleware>();
+        }
+    }
+}
\ No newline at end of file

src/DotNetCore.CAP/Dashboard/GatewayProxy/Requester/HttpClientBuilder.cs

+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Net.Http;
+using System.Threading.Tasks; 
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy.Requester
+{
+    internal class HttpClientBuilder : IHttpClientBuilder
+    {
+        private readonly Dictionary<int, Func<DelegatingHandler>> _handlers = new Dictionary<int, Func<DelegatingHandler>>();
+
+        public IHttpClient Create()
+        {
+            var httpclientHandler = new HttpClientHandler();
+            
+            var client = new HttpClient(CreateHttpMessageHandler(httpclientHandler));                
+            
+            return new HttpClientWrapper(client);
+        }
+
+        private HttpMessageHandler CreateHttpMessageHandler(HttpMessageHandler httpMessageHandler)
+        {            
+   
+            _handlers
+                .OrderByDescending(handler => handler.Key)
+                .Select(handler => handler.Value)
+                .Reverse()
+                .ToList()
+                .ForEach(handler =>
+                {
+                    var delegatingHandler = handler();
+                    delegatingHandler.InnerHandler = httpMessageHandler;
+                    httpMessageHandler = delegatingHandler;
+                });
+            return httpMessageHandler;
+        }
+    }
+
+    /// <summary>
+    /// This class was made to make unit testing easier when HttpClient is used.
+    /// </summary>
+    internal class HttpClientWrapper : IHttpClient
+    {
+        public HttpClient Client { get; }
+
+        public HttpClientWrapper(HttpClient client)
+        {
+            Client = client;
+        }
+
+        public Task<HttpResponseMessage> SendAsync(HttpRequestMessage request)
+        {
+            return Client.SendAsync(request);
+        }
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/Requester/HttpClientHttpRequester.cs

+using System;
+using System.Collections.Concurrent;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy.Requester
+{
+    public class HttpClientHttpRequester : IHttpRequester
+    {
+        private readonly IHttpClientCache _cacheHandlers;
+        private readonly ILogger _logger;
+
+        public HttpClientHttpRequester(ILoggerFactory loggerFactory, IHttpClientCache cacheHandlers)
+        {
+            _logger = loggerFactory.CreateLogger<HttpClientHttpRequester>();
+            _cacheHandlers = cacheHandlers;
+        }
+
+        public async Task<HttpResponseMessage> GetResponse(HttpRequestMessage request)
+        {
+            var builder = new HttpClientBuilder();
+
+            var cacheKey = GetCacheKey(request, builder);
+
+            var httpClient = GetHttpClient(cacheKey, builder);
+
+            try
+            {
+                return await httpClient.SendAsync(request);
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError("Error making http request, exception:" + exception.Message);
+                throw exception;
+            }
+            finally
+            {
+                _cacheHandlers.Set(cacheKey, httpClient, TimeSpan.FromHours(24));
+            }
+
+        }
+
+        private IHttpClient GetHttpClient(string cacheKey, IHttpClientBuilder builder)
+        {
+            var httpClient = _cacheHandlers.Get(cacheKey);
+
+            if (httpClient == null)
+            {
+                httpClient = builder.Create();
+            }
+            return httpClient;
+        }
+
+        private string GetCacheKey(HttpRequestMessage request, IHttpClientBuilder builder)
+        {
+            string baseUrl = $"{request.RequestUri.Scheme}://{request.RequestUri.Authority}";
+
+            return baseUrl;
+        }
+    }
+}
\ No newline at end of file

src/DotNetCore.CAP/Dashboard/GatewayProxy/Requester/IHttpClient.cs

+using System;
+using System.Net.Http;
+using System.Threading.Tasks;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy.Requester
+{
+    public interface IHttpClient
+    {
+        HttpClient Client { get; }
+
+        Task<HttpResponseMessage> SendAsync(HttpRequestMessage request);
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/Requester/IHttpClientBuilder.cs

+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Threading.Tasks;
+using System.Net;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy.Requester
+{
+    public interface IHttpClientBuilder
+    {
+        /// <summary>
+        /// Creates the <see cref="HttpClient"/>
+        /// </summary>
+        IHttpClient Create();
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/Requester/IHttpClientCache.cs

+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Threading.Tasks;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy.Requester
+{
+    public interface IHttpClientCache
+    {
+        bool Exists(string id);
+        IHttpClient Get(string id);
+        void Remove(string id);
+        void Set(string id, IHttpClient handler, TimeSpan expirationTime);
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/Requester/IHttpRequester.cs

+using System.Net.Http;
+using System.Threading.Tasks;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy.Requester
+{
+    public interface IHttpRequester
+    {
+        Task<HttpResponseMessage> GetResponse(HttpRequestMessage request);
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/Requester/MemoryHttpClientCache.cs

+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Threading.Tasks;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy.Requester
+{
+    public class MemoryHttpClientCache : IHttpClientCache
+    {
+        private readonly ConcurrentDictionary<string, ConcurrentQueue<IHttpClient>> _httpClientsCache = new ConcurrentDictionary<string, ConcurrentQueue<IHttpClient>>();
+
+        public void Set(string id, IHttpClient client, TimeSpan expirationTime)
+        {
+            ConcurrentQueue<IHttpClient> connectionQueue;
+            if (_httpClientsCache.TryGetValue(id, out connectionQueue))
+            {
+                connectionQueue.Enqueue(client);
+            }
+            else
+            {
+                connectionQueue = new ConcurrentQueue<IHttpClient>();
+                connectionQueue.Enqueue(client);
+                _httpClientsCache.TryAdd(id, connectionQueue);
+            }
+        }
+
+        public bool Exists(string id)
+        {
+            ConcurrentQueue<IHttpClient> connectionQueue;
+            return _httpClientsCache.TryGetValue(id, out connectionQueue);
+        }
+
+        public IHttpClient Get(string id)
+        {
+            IHttpClient client= null;
+            ConcurrentQueue<IHttpClient> connectionQueue;
+            if (_httpClientsCache.TryGetValue(id, out connectionQueue))
+            {
+                connectionQueue.TryDequeue(out client);
+            }
+            return client;
+        }
+
+        public void Remove(string id)
+        {
+            ConcurrentQueue<IHttpClient> connectionQueue;
+            _httpClientsCache.TryRemove(id, out connectionQueue);
+        }        
+    }
+}

src/DotNetCore.CAP/Dashboard/GatewayProxy/Requester/Middleware/HttpRequesterMiddleware.cs

+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging; 
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy.Requester.Middleware
+{
+    public class HttpRequesterMiddleware : GatewayProxyMiddleware
+    {
+        private readonly RequestDelegate _next;
+        private readonly IHttpRequester _requester;
+        private readonly ILogger _logger;
+
+        public HttpRequesterMiddleware(RequestDelegate next,
+            ILoggerFactory loggerFactory,
+            IHttpRequester requester, 
+            IRequestScopedDataRepository requestScopedDataRepository)
+            :base(requestScopedDataRepository)
+        {
+            _next = next;
+            _requester = requester;
+            _logger = loggerFactory.CreateLogger<HttpRequesterMiddleware>();
+        }
+
+        public async Task Invoke(HttpContext context)
+        {
+            _logger.LogDebug("started calling requester middleware");
+
+            var response = await _requester.GetResponse(Request);
+ 
+
+            _logger.LogDebug("setting http response message");
+
+            SetHttpResponseMessageThisRequest(response);
+
+            _logger.LogDebug("returning to calling middleware");
+        }
+    }
+}
\ No newline at end of file

src/DotNetCore.CAP/Dashboard/GatewayProxy/Requester/Middleware/HttpRequesterMiddlewareExtensions.cs

+using Microsoft.AspNetCore.Builder;
+
+namespace DotNetCore.CAP.Dashboard.GatewayProxy.Requester.Middleware
+{
+    public static class HttpRequesterMiddlewareExtensions
+    {
+        public static IApplicationBuilder UseHttpRequesterMiddleware(this IApplicationBuilder builder)
+        {
+            return builder.UseMiddleware<HttpRequesterMiddleware>();
+        }
+    }
+}
\ No newline at end of file

src/DotNetCore.CAP/DotNetCore.CAP.csproj

@@ -143,7 +143,4 @@
       <Generator>RazorGenerator</Generator>
     </None>
   </ItemGroup>
-  <ItemGroup>
-    <Folder Include="Dashboard\Consul\" />
-  </ItemGroup>
 </Project>
\ No newline at end of file