有助于消除环路异步接收机由于内容长度= 0在HTTP响应

Question

一些web服务器返回内容长度在HTTP响应报头设置为零。我想在这种情况下接收所有的数据确定性和高性能的解决方案。

URL已知表现出这种行为（下面附加的URL）：

HTTP：/ /www.washingtonpost.com/wp-dyn/content/article/2010/02/12/AR2010021204894.html?hpid=topnews

标题

Cache-control:no-cache
Connection:close
Content-Encoding:gzip
Content-type:text/html
Server:Web Server
Transfer-encoding:chunked

我的当前解决方案不能保证得到所有的数据由于MaxTries恒定的，并且缓慢由于Thread.sleep代码（）

private bool MoreDataIsAvailable()
{
    int avail = _socket.Available;
    if (avail == 0 &&
        _contentLength != null && _contentLength == 0)
    {
        int tries = 0;
        while (avail == 0 && tries < MaxTries)
        {
            Thread.Sleep(5);
            _socket.Poll(1000, SelectMode.SelectRead);
            avail = _socket.Available;
            tries++;
            if (avail > 0)
            {
                Console.WriteLine(_socket.Handle + " avail = " + avail + " received = " + _bytes.Length + " && tries = " + tries);
            }
        }
    }
    return avail > 0;
}

在上下文用法：

private void ReceiveCallback(object sender, SocketAsyncEventArgs e)
{
    if (ConnectionWasClosed(e) || HadSocketError(e))
    {
        _receiveDone.Set();
        return;
    }

    StoreReceivedBytes(e);

    if (AllBytesReceived())
    {
        _receiveDone.Set();
        return;
    }

    if (MoreDataIsExpected() || MoreDataIsAvailable())
    {
        WaitForBytes(e);
    }
    else
    {
        _receiveDone.Set();
    }
}

示例输出：

1436 avail = 3752 received = 1704 && tries = 9
1436 avail = 3752 received = 9208 && tries = 8
1436 avail = 3752 received = 12960 && tries = 9
1436 avail = 3752 received = 20464 && tries = 8
1436 avail = 3752 received = 27968 && tries = 7
1436 avail = 7504 received = 31720 && tries = 1
1436 avail = 3752 received = 39224 && tries = 6

编辑：

尼古拉观察到，用一个编码传输的反应：分块标题需要特殊的处理，但其端部可以确定性地被检测到。

不包括分块的响应，然而，仍然有在我的捕获所有方法最终其它网址，例子：

http://www.biomedcentral.com/1471-2105/6/197

标题

Cache-control:private
Connection:close
Content-Type:text/html
P3P:policyref="/w3c/p3p.xml", CP="NOI DSP COR CURa ADMa DEVa TAIa OUR BUS PHY ONL UNI COM NAV INT DEM PRE"
Server:Microsoft-IIS/5.0
X-Powered-By:ASP.NET

http://slampp.abangadek.com/info/

标题

Connection:close
Content-Type:text/html
Server:Apache/2.2.8 (Ubuntu) DAV/2 PHP/5.2.4-2ubuntu5.3 with Suhosin-Patch mod_ruby/1.2.6 Ruby/1.8.6(2007-09-24) mod_ssl/2.2.8 OpenSSL/0.9.8g
X-Cache:MISS from server03.abangadek.com
X-Powered-By:PHP/5.2.4-2ubuntu5.3

http://video.forbes.com/ embedvideo /？格式=帧＆高度= 515＆宽度= 336＆模式=渲染＆网络链接= 1

标题

Connection:close
Content-Language:en-US
Content-Type:text/html;charset=ISO-8859-1
Server:Apache-Coyote/1.1

我想知道我可以看看在这些反应，像Transfer-Encoding头为第一个URL，给出了一个线索确定性读取整个响应，以便调用我的方法能避免什么。

Answer 1

从给定的URL看起来你是在寻找 HTTP分块传输编码 时，它允许服务器开始发送总长度之前的响应，同时仍然允许在客户端可靠地确定所述响应的端是已知的。

另请参见 RFC 2616，部分3.6.1 。