无侵入方面编程-用HttpModule+SoapExtension监视页面执行参数（二）

上一篇文章 "无侵入方面编程-用HttpModule+SoapExtension监视页面执行参数(一）"中，我们实现了监视每个页面的执行情况和调用WebService的简单信息。

这次我们继续深入一下SoapExtension的应用，在不改变Soap的WSDL文档的情况下，配合在Dotnet编写的WebService站点配置我们编写的SoapExtension，来穿透传输我们自定义的数据对象。由于SoapExtension是全局的，我们还要加一些标识来区分服务器是否已经配置了我们的SoapExtension，从而不影响其它的WebService调用。

在SoapExtension中，我想到有两种方案：
一种是直接在SoapMessage.Headers中插入自定义的SoapHeader对象，然后在客户端的序列化后，从SoapUnknownHeader中取出数据，然后反序列化成自定义的对象。
第二种是对SoapMessage.ContentType 添加一个额外的标识，在另一方检测这个标识，来从流中取出自己长度的数据。反序列化成自定义的对象。

我感觉第二种方案比较简单，高效，我们看一下代码：

/// <summary>
/// WSInvokeMonitorExtension 的摘要说明。
/// </summary>
public class StreamWSInvokeMonitorExtension : SoapExtension
{
private const string WSInvokeMonitorKey = "__WSInvokeMonitorKey__";
private const int MaxDataLength = 5 * 1024 * 1024; //5M
private XmlSerializer serializer = new XmlSerializer(typeof(DbConnInfo));
private Stream originStream;
private Stream usingStream = new MemoryStream();
private WSInvokeInfo invokeInfo = new WSInvokeInfo();
public override System.IO.Stream ChainStream(System.IO.Stream stream)
{
originStream = stream;
return usingStream;
}

public override object GetInitializer(Type serviceType)
{
return null;
}

public override object GetInitializer(LogicalMethodInfo methodInfo, SoapExtensionAttribute attribute)
{
return null;
}

public override void Initialize(object initializer)
{

}

public override void ProcessMessage(SoapMessage message)
{
if(message is SoapClientMessage)
{
switch (message.Stage)
{
case SoapMessageStage.BeforeSerialize:
this.invokeInfo.BeginInvokeTime = DateTime.Now;
this.invokeInfo.MethodName = message.MethodInfo.Name;
break;

case SoapMessageStage.AfterSerialize:
usingStream.Seek(0, SeekOrigin.Begin);
CopyStream(usingStream, originStream);
break;

case SoapMessageStage.BeforeDeserialize:
usingStream.SetLength(0);
CopyStream(originStream, usingStream);
usingStream.Seek(0, SeekOrigin.Begin);
if(message.ContentType.IndexOf("ExtInfo=true") != -1){
//先读出自己的信息
byte[] bytesFlags = new byte[]{66,69}; // BE 标识

if(usingStream.ReadByte() == bytesFlags[0]) //检验标志位
{
byte[] bytesLength = new byte[BitConverter.GetBytes((Int32)0).Length];
usingStream.Read(bytesLength,0, bytesLength.Length); //读取长度
int length = BitConverter.ToInt32(bytesLength,0);

if(length < MaxDataLength) //检验数据是否非法
{
if(usingStream.ReadByte() == bytesFlags[1]) //检验标志位
{
byte[] bytesData = new byte[length];
usingStream.Read(bytesData,0, bytesData.Length);
using(MemoryStream ms = new MemoryStream(bytesData))
{
DbConnInfo header = serializer.Deserialize(ms) as DbConnInfo;
Debug.WriteLine(header.Info);
}

break;
}

}

}

//数据不对,则重置流位置
usingStream.Position = 0;
}

break;

// About to call methods
case SoapMessageStage.AfterDeserialize:
//添加到Module记录
this.invokeInfo.EndInvokeTime = DateTime.Now;
PageInfo pageInfo = (PageInfo)HttpContext.Current.Items[WSInvokeMonitorKey] ;
if(pageInfo != null)
{
pageInfo.AppendInvokeInfo(this.invokeInfo);
}

break;

// After Method call

default:
throw new Exception("No stage such as this
[System.Serializable]
public class DbConnInfoSoapHeader
{
private string info;
public string Info
{
get { return info; }
set { info = value; }
}

public DbConnInfoSoapHeader()
{

}

public DbConnInfoSoapHeader(string info)
{
this.Info = info;
}

}

[System.Serializable]
public class SoapHeaderWrap : SoapHeader
{
private byte[] soapData = null;
private object data;

[XmlIgnoreAttribute]
[SoapIgnoreAttribute]
public object Data
{
get { return data; }
set
{
data = value;
soapData = null;
}
}
private string key;
[XmlAttribute]
public string Key
{
get { return key; }
set { key = value; }
}

[XmlAttribute]
public string TypeName
{
get{

return this.Data.GetType().AssemblyQualifiedName;
}
set{}
}

public byte[] SoapData
{
get
{
if(soapData == null && this.Data != null)
{
using(MemoryStream ms = new MemoryStream())
using(StreamWriter sw = new StreamWriter(ms,new UTF8Encoding(false)))
{
XmlSerializer serializer = new XmlSerializer(this.Data.GetType());
serializer.Serialize(sw, this.Data);
ms.Position = 0;
soapData = ms.ToArray();
}

}

return soapData;
}
set {

}
}

public SoapHeaderWrap(string key, object soapData)
{
this.Key = key;
this.Data = soapData;
}

public SoapHeaderWrap(string key)
:this(key,null)
{
}

public SoapHeaderWrap()
:this(string.Empty)
{

}

}
http://www.cnblogs.com/evlon/archive/2009/06/01/1493923.html