XmlDownloadManager.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Xml / System / Xml / XmlDownloadManager.cs / 1 / XmlDownloadManager.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
 
namespace System.Xml { 

    using System; 
    using System.IO;
    using System.Net;
    using System.Security;
    using System.Xml.Schema; 
    using System.Collections;
    using System.Security.Policy; 
 
//
// XmlDownloadManager 
//
    internal class XmlDownloadManager {
        Hashtable connections;
 
        internal Stream GetStream( Uri uri, ICredentials credentials ) {
            if ( uri.Scheme == "file" ) { 
                return new FileStream( uri.LocalPath, FileMode.Open, FileAccess.Read, FileShare.Read, 1 ); 
            }
            else { 
                return GetNonFileStream( uri, credentials );
            }
        }
 
        private Stream GetNonFileStream( Uri uri, ICredentials credentials ) {
            WebRequest req = WebRequest.Create( uri ); 
            if ( credentials != null ) { 
                req.Credentials = credentials;
            } 
            WebResponse resp = req.GetResponse();
            HttpWebRequest webReq = req as HttpWebRequest;
            if ( webReq != null ) {
                lock ( this ) { 
                    if ( connections == null ) {
                        connections = new Hashtable(); 
                    } 
                    OpenedHost openedHost = (OpenedHost)connections[webReq.Address.Host];
                    if ( openedHost == null ) { 
                        openedHost = new OpenedHost();
                    }

                    if ( openedHost.nonCachedConnectionsCount < webReq.ServicePoint.ConnectionLimit - 1 ) { 
                        // we are not close to connection limit -> don't cache the stream
                        if ( openedHost.nonCachedConnectionsCount == 0 ) { 
                            connections.Add( webReq.Address.Host, openedHost ); 
                        }
                        openedHost.nonCachedConnectionsCount++; 
                        return new XmlRegisteredNonCachedStream( resp.GetResponseStream(), this, webReq.Address.Host );
                    }
                    else {
                        // cache the stream and save the connection for the next request 
                        return new XmlCachedStream( resp.ResponseUri, resp.GetResponseStream() );
                    } 
                } 
            }
            else { 
                return resp.GetResponseStream();
            }
        }
 
        internal void Remove( string host ) {
            lock ( this ) { 
                OpenedHost openedHost = (OpenedHost)connections[host]; 
                if ( openedHost != null ) {
                    if ( --openedHost.nonCachedConnectionsCount == 0 ) { 
                        connections.Remove( host );
                    }
                }
            } 
        }
 
    } 

// 
// OpenedHost
//
    internal class OpenedHost {
        internal int nonCachedConnectionsCount; 
    }
 
// 
// XmlRegisteredNonCachedStream
// 
    internal class XmlRegisteredNonCachedStream : Stream {
        protected Stream stream;
        XmlDownloadManager downloadManager;
        string host; 

        internal XmlRegisteredNonCachedStream( Stream stream, XmlDownloadManager downloadManager, string host ) { 
            this.stream = stream; 
            this.downloadManager = downloadManager;
            this.host = host; 
        }

        ~XmlRegisteredNonCachedStream() {
            if ( downloadManager != null ) { 
                downloadManager.Remove( host );
            } 
            stream = null; 
            // The base class, Stream, provides its own finalizer
        } 

        protected override void Dispose( bool disposing ) {
            try {
                if ( disposing && stream != null ) { 
                    if ( downloadManager != null ) {
                        downloadManager.Remove( host ); 
                    } 
                    stream.Close();
                } 
                stream = null;
                GC.SuppressFinalize( this ); // do not call finalizer
            }
            finally { 
                base.Dispose( disposing );
            } 
        } 

        // 
        // Stream
        //
        public override IAsyncResult BeginRead( byte[] buffer, int offset, int count, AsyncCallback callback, object state ) {
            return stream.BeginRead( buffer, offset, count, callback, state ); 
        }
 
        public override IAsyncResult BeginWrite( byte[] buffer, int offset, int count, AsyncCallback callback, object state ) { 
            return BeginWrite( buffer, offset, count, callback, state );
        } 

        public override int EndRead( IAsyncResult asyncResult ) {
            return stream.EndRead( asyncResult );
        } 

        public override void EndWrite( IAsyncResult asyncResult ) { 
            stream.EndWrite( asyncResult ); 
        }
 
        public override void Flush() {
            stream.Flush();
        }
 
        public override int Read( byte[] buffer, int offset, int count ) {
            return stream.Read( buffer, offset, count ); 
        } 

        public override int ReadByte() { 
            return stream.ReadByte();
        }

        public override long Seek( long offset, SeekOrigin origin ) { 
            return stream.Seek( offset, origin );
        } 
 
        public override void SetLength( long value ) {
            stream.SetLength( value ); 
        }

        public override void Write( byte[] buffer, int offset, int count ) {
            stream.Write( buffer, offset, count ); 
        }
 
        public override void WriteByte( byte value ) { 
            stream.WriteByte( value );
        } 

        public override Boolean CanRead {
            get { return stream.CanRead; }
        } 

        public override Boolean CanSeek { 
            get { return stream.CanSeek; } 
        }
 
        public override Boolean CanWrite {
            get { return stream.CanWrite; }
        }
 
        public override long Length {
            get { return stream.Length; } 
        } 

        public override long Position { 
            get { return stream.Position; }
            set { stream.Position = value; }
        }
    } 

// 
// XmlCachedStream 
//
    internal class XmlCachedStream : MemoryStream { 
        private const int MoveBufferSize = 4096;

        private Uri uri;
 
        internal XmlCachedStream( Uri uri, Stream stream )
            : base() { 
 
            this.uri = uri;
 
            try {
                byte[] bytes = new byte[MoveBufferSize];
                int read = 0;
                while ( ( read = stream.Read( bytes, 0, MoveBufferSize ) ) > 0 ) { 
                    this.Write( bytes, 0, read );
                } 
                base.Position = 0; 
            }
            finally { 
                stream.Close();
            }
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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XmlDownloadManager.cs source code in C# .NET

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