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：
/// 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
");}
}
{
switch (message.Stage)
{
// Incoming from client
case SoapMessageStage.BeforeDeserialize:
usingStream.SetLength(0);
CopyStream(originStream, usingStream);
usingStream.Seek(0, SeekOrigin.Begin);
break;
// About to call methods
case SoapMessageStage.AfterDeserialize:
break;
// After Method call
case SoapMessageStage.BeforeSerialize:
//设置自定义Header
usingStream.SetLength(0); //清空并先写入自定义的信息
byte[] bytesData = null;
using(MemoryStream ms = new MemoryStream())
{
serializer.Serialize(ms,new DbConnInfo("3个数据库连接")); //服务端自定义的信息
bytesData = ms.ToArray();
}
message.ContentType += ";ExtInfo=true";
//写入标识
byte[] bytesFlags = new byte[]{66,69}; // BE
usingStream.WriteByte(bytesFlags[0]);
//写入长度
byte[] dataLength = BitConverter.GetBytes(bytesData.Length);
usingStream.Write(dataLength, 0, dataLength.Length);
//再写入标志
usingStream.WriteByte(bytesFlags[1]);
//写入数据
usingStream.Write(bytesData, 0, bytesData.Length);
break;
// Outgoing to other
case SoapMessageStage.AfterSerialize:
usingStream.Seek(0, SeekOrigin.Begin);
CopyStream(usingStream, originStream);
break;
default:
throw new Exception("No stage such as this
");}
}
}
private void CopyStream(Stream src, Stream des)
{
byte[] buf = new byte[1024];
int length = 0;
do
{
length = src.Read(buf,0,buf.Length);
des.Write(buf,0,length);
} while (length == buf.Length);
}
}
[System.Serializable]
{
private string info;
public string Info
{
get { return info; }
set { info = value; }
}
public DbConnInfo()
{
}
public DbConnInfo(string info)
{
this.Info = info;
}
}
代码中，在服务端写入标识： message.ContentType += ";ExtInfo=true";
然后在客户端检测：if(message.ContentType.IndexOf("ExtInfo=true") != -1){...}
这样便保证了不会影响其它没有加载Soap扩展的调用。
到目前为至，我们已经成功的把服务端的信息对象，在不改变WSDL的情况下，无侵入的传递到调用端。具体收集什么信息，就要在WebService端进行收集了！我这里的要求是收集数据库连接的情况，下一次继续介绍吧。
附：方案一实现代码：
方案一代码