trace.cs

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using System;
using System.IO;
using System.Web.Services.Protocols;

[AttributeUsage(AttributeTargets.Method)]
public class TraceExtensionAttribute : SoapExtensionAttribute {

    private string filename = "c:\\log.txt";
    private int priority;

    public override Type ExtensionType {
        get { return typeof(TraceExtension); }
    }

    public override int Priority {
        get { return priority; }
        set { priority = value; }
    }

    public string Filename {
        get {
            return filename;
        }
        set {
            filename = value;
        }
    }
}

public class TraceExtension : SoapExtension {

    Stream oldStream;
    Stream newStream;
    string filename;

    public override object GetInitializer(LogicalMethodInfo methodInfo, SoapExtensionAttribute attribute) {
        return ((TraceExtensionAttribute) attribute).Filename;
    }

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

	public override void Initialize(object initializer) {
		filename = (string) initializer;
	}

    public override void ProcessMessage(SoapMessage message) {
        switch (message.Stage) {

        case SoapMessageStage.BeforeSerialize:
            break;

        case SoapMessageStage.AfterSerialize:
            WriteOutput( message );
            break;

        case SoapMessageStage.BeforeDeserialize:
            WriteInput( message );
            break;

        case SoapMessageStage.AfterDeserialize:
            break;

        default:
            throw new Exception("invalid stage");
        }
    }

    public override Stream ChainStream( Stream stream ){
        oldStream = stream;
        newStream = new MemoryStream();
        return newStream;
    }

    public void WriteOutput( SoapMessage message ){
        newStream.Position = 0;
       	FileStream fs = new FileStream(filename, FileMode.Append, FileAccess.Write);
        StreamWriter w = new StreamWriter(fs);
        w.WriteLine("---------------------------------- Response at " + DateTime.Now);
        w.Flush();
        Copy(newStream, fs);
        fs.Close();
        newStream.Position = 0;
        Copy(newStream, oldStream);
    }

    public void WriteInput( SoapMessage message ){
        Copy(oldStream, newStream);
       	FileStream fs = new FileStream(filename, FileMode.Append, FileAccess.Write);
        StreamWriter w = new StreamWriter(fs);
        w.WriteLine("================================== Request at " + DateTime.Now);
        w.Flush();
        newStream.Position = 0;
        Copy(newStream, fs);
        fs.Close();
        newStream.Position = 0;
    }

    void Copy(Stream from, Stream to) {

        TextReader reader = new StreamReader(from);
        TextWriter writer = new StreamWriter(to);
        writer.WriteLine(reader.ReadToEnd());
        writer.Flush();
    }
}