.NET中的异步XmlReader？

Question

有没有办法异步访问XmlReader？xml从许多不同的客户端(例如XMPP)进入网络; 它是<action>...</action>标签的恒定流.

我所追求的是能够使用类似BeginRead/EndRead的界面.我设法提出的最佳解决方案是在底层网络流上对0字节进行异步读取,然后当一些数据到达时,在XmlReader上调用Read-但是这将阻塞直到节点的所有数据变得可用了.该解决方案看起来大致如此

private Stream syncstream;
private NetworkStream ns;
private XmlReader reader;

//this code runs first
public void Init()
{
    syncstream = Stream.Synchronized(ns);
    reader = XmlReader.Create(syncstream);
    byte[] x = new byte[1];
    syncstream.BeginRead(x, 0, 0, new AsynchronousCallback(ReadCallback), null);
}

private void ReadCallback(IAsyncResult ar)
{
    syncstream.EndRead(ar);
    reader.Read(); //this will block for a while, until the entire node is available
    //do soemthing to the xml node
    byte[] x = new byte[1];
    syncstream.BeginRead(x, 0, 0, new AsynchronousCallback(ReadCallback), null);
}

编辑:如果一个字符串包含一个完整的xml节点,这是一个可能的算法？

Func<string, bool> nodeChecker = currentBuffer =>
                {
                    //if there is nothing, definetly no tag
                    if (currentBuffer == "") return false;
                    //if we have <![CDATA[ and not ]]>, hold on, else pass it on
                    if (currentBuffer.Contains("<![CDATA[") && !currentBuffer.Contains("]]>")) return false;
                    if (currentBuffer.Contains("<![CDATA[") && currentBuffer.Contains("]]>")) return true;
                    //these tag-related things will also catch <? ?> processing instructions
                    //if there is a < but no >, we still have an open tag
                    if (currentBuffer.Contains("<") && !currentBuffer.Contains(">")) return false;
                //if there is a <...>, we have a complete element.
                //>...< will never happen because we will pass it on to the parser when we get to >
                if (currentBuffer.Contains("<") && currentBuffer.Contains(">")) return true;
                //if there is no < >, we have a complete text node
                if (!currentBuffer.Contains("<") && !currentBuffer.Contains(">")) return true;
                //> and no < will never happen, we will pass it on to the parser when we get to >
                //by default, don't block
                return false;
            };

Answer 1

XmlReader 以 4kB 块的形式进行缓冲，如果我还记得几年前我研究这个问题的话。您可以将入站数据填充到 4kB（恶心！），或者使用更好的解析器。我通过将 James Clark 的 XP (Java) 移植到 C# 作为 Jabber-Net 的一部分来修复此问题，如下所示：

http://code.google.com/p/jabber-net/source/browse/#svn/trunk/xpnet

它是 LGPL，仅处理 UTF8，未打包使用，并且几乎没有文档，因此我不建议使用它。:)