Question

在我的旧非OWIN API中，我使用MessageHanlder来记录所有HttpRequests和HttpResponses。这是MessageHandler：

public class MessageHandler : DelegatingHandler
{
    private static readonly ILog RequestApiLogger = LogManager.GetLogger("RequestApiPacketLogger");
    private static readonly ILog ResponseApiLogger = LogManager.GetLogger("ResponseApiPacketLogger");

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var correlationId = Guid.NewGuid();

        RequestApiLogger.LogHttpRequest(request, correlationId);

        return await base.SendAsync(request, cancellationToken).ContinueWith(
            task =>
            {
                var response = task.Result;
                response.Headers.Add("http-tracking-id", correlationId.ToString("D"));
                ResponseApiLogger.LogHttpResponse(response, correlationId);
                return response;

            }, cancellationToken);
    }
}

但是，在我的新项目中，我可以编写自定义OWIN中间件，使用类似这样的OwinContext做类似的事情：

//use an alias for the OWIN AppFunc
using AppFunc = Func<IDictionary<string, object>, Task>;

public class LoggingMiddleware
{
    private readonly AppFunc _next;

    public LoggingMiddleware(AppFunc next)
    {
        _next = next;
    }

    public async Task Invoke(IDictionary<string, object> environment)
    {
        IOwinContext context = new OwinContext(environment);

        // Get the identity 
        var identity = (context.Request.User != null && context.Request.User.Identity.IsAuthenticated)
            ? context.Request.User.Identity.Name
            : "(anonymous)";

        // Buffer the request (body is a string, we can use this to log the request later
        var requestBody = new StreamReader(context.Request.Body).ReadToEnd();
        var requestData = Encoding.UTF8.GetBytes(requestBody);
        context.Request.Body = new MemoryStream(requestData);

        var apiPacket = new ApiPacket
        {
            CallerIdentity = identity,
            Request = requestBody,
            RequestLength = context.Request.Body.Length
        };

        // Buffer the response
        var responseBuffer = new MemoryStream();
        var responseStream = context.Response.Body;
        context.Response.Body = responseBuffer;

        // add the "http-tracking-id" response header so the user can correlate back to this entry
        var responseHeaders = (IDictionary<string, string[]>)environment["owin.ResponseHeaders"];
        responseHeaders["http-tracking-id"] = new[] { apiPacket.TrackingId.ToString("d") };

        await _next.Invoke(environment);

        responseBuffer.Seek(0, SeekOrigin.Begin);
        var reader = new StreamReader(responseBuffer);
        apiPacket.Response = await reader.ReadToEndAsync();
        apiPacket.ResponseLength = context.Response.ContentLength ?? 0;

        WriteRequestHeaders(context.Request, apiPacket);
        WriteResponseHeaders(context.Response, apiPacket);

        // You need to do this so that the response we buffered is flushed out to the client application.
        responseBuffer.Seek(0, SeekOrigin.Begin);
        await responseBuffer.CopyToAsync(responseStream);

        //TODO: persist the ApiPacket in the database
    }

    private static void WriteRequestHeaders(IOwinRequest request, ApiPacket packet)
    {
        packet.Verb = request.Method;
        packet.RequestUri = request.Uri;
        packet.RequestHeaders = "{\r\n" + string.Join(Environment.NewLine, request.Headers.Select(kv => "\t" + kv.Key + "=" + string.Join(",", kv.Value))) + "\r\n}";
    }

    private static void WriteResponseHeaders(IOwinResponse response, ApiPacket packet)
    {
        packet.StatusCode = response.StatusCode;
        packet.ReasonPhrase = response.ReasonPhrase;
        packet.ResponseHeaders = "{\r\n" + string.Join(Environment.NewLine, response.Headers.Select(kv => "\t" + kv.Key + "=" + string.Join(",", kv.Value))) + "\r\n}";
    }
}

我正在使用log4net将信息写入SQL2012数据库。两种方式都实现了我的目标但是，我正在寻找使用一种方法而不是另一种方法的理由。我应该使用自定义OWIN中间件还是MessageHandler，为什么？提前谢谢。

Answer 1

由于您已经有MessageHandler个实现，我建议您使用它，除非您有其他原因。

但是，如果您有其他OwinMiddleware组件需要（或将从中受益）日志记录功能，那么将我的日志迁移到OwinMiddleware的一个正当理由是假的，您正在使用WebApi，MessageHandlers将在请求管道中的所有OwinMiddleware之后运行。

Answer 2

看起来我将使用OWIN中间件。我发现在MessageHandler中，Principal.IIdentity尚未解决。例如，如果我在我的消息处理程序，API控制器的构造函数和API方法中放置断点，这就是我所看到的（按顺序）。

使用邮件处理程序

在MessageHandler＆gt; Principal.IIdentity尚未解决。
在API控制器的构造函数中＆gt; Principal.IIDentity尚未解决。
在API控制器的GET方法中，最终解决了Principal.IIdentity。

因此，我无法撤出并在MessageHandler中记录授权用户的id。

然而，当使用OWIN中间件时，Principal.IIdentity IS在那里解析，所以我可以在那时将userId写入我的日志表。这就是我决定使用中间件的原因。

也许某人可以提供一些关于IIDentity何时在API项目中设置的清晰度。

使用OWIN中间件或委托MessgaeHandler来记录api请求/响应？

2 个答案: