Cara: Mengaktifkan Streaming
Windows Communication Foundation (WCF) dapat mengirim pesan menggunakan transfer aliran atau buffer. Dalam mode transfer buffer default, pesan harus sepenuhnya dikirim sebelum penerima bisa membacanya. Dalam mode transfer streaming, penerima dapat mulai memproses pesan sebelum dikirim sepenuhnya. Mode streaming berguna saat informasi yang diteruskan isinya panjang dan dapat diproses secara serial. Mode streaming juga berguna saat pesan terlalu besar untuk sepenuhnya di-buffer.
Untuk mengaktifkan streaming, tentukan OperationContract
dengan tepat dan aktifkan streaming di tingkat transportasi.
Untuk streaming data
Untuk streaming data,
OperationContract
untuk layanan harus memenuhi dua persyaratan:Parameter berisi data yang akan di-streaming harus menjadi satu-satunya parameter dalam metode ini. Misalnya, jika pesan input adalah yang akan di-streaming, operasi harus memiliki satu parameter input. Demikian pula, jika pesan output akan dialirkan, operasi harus memiliki tepat satu parameter output atau nilai yang dikembalikan.
Setidaknya salah satu jenis parameter dan nilai yang ditampilkan harus, Stream, Message atau IXmlSerializable.
Berikut ini adalah contoh kontrak untuk data yang di-streaming.
[ServiceContract(Namespace = "http://Microsoft.ServiceModel.Samples")] public interface IStreamingSample { [OperationContract] Stream GetStream(string data); [OperationContract] bool UploadStream(Stream stream); [OperationContract] Stream EchoStream(Stream stream); [OperationContract] Stream GetReversedStream(); }
<ServiceContract(Namespace:="http://Microsoft.ServiceModel.Samples")> _ Public Interface IStreamingSample <OperationContract()> _ Function GetStream(ByVal data As String) As Stream <OperationContract()> _ Function UploadStream(ByVal stream As Stream) As Boolean <OperationContract()> _ Function EchoStream(ByVal stream As Stream) As Stream <OperationContract()> _ Function GetReversedStream() As Stream End Interface
Operasi
GetStream
menerima beberapa data input buffer sebagaistring
, yang di-buffer, dan menampilkanStream
, yang di-streaming. SebaliknyaUploadStream
menggunakanStream
(di-streaming) dan menampilkanbool
(di-buffer).EchoStream
menggunakan dan menampilkanStream
dan merupakan contoh operasi yang pesan input dan output-nya di-streaming. Di akhir,GetReversedStream
tidak menggunakan input dan menampilkanStream
(di-streaming).Streaming harus diaktifkan pada pengikatan. Anda menetapkan properti
TransferMode
, yang dapat menggunakan salah satu nilai berikut:Buffered
,Streamed
, yang memungkinkan komunikasi streaming secara dua arah.StreamedRequest
, yang memungkinkan streaming permintaan saja.StreamedResponse
, yang memungkinkan streaming respons saja.
BasicHttpBinding
mengekspos propertiTransferMode
pada pengikatan, seperti halnyaNetTcpBinding
danNetNamedPipeBinding
. PropertiTransferMode
juga bisa diatur pada elemen pengikatan transportasi dan digunakan dalam pengikatan kustom.Sampel berikut menunjukkan cara mengatur
TransferMode
menurut kode dan dengan mengubah file konfigurasi. Sampel juga keduanya mengatur propertimaxReceivedMessageSize
ke 64 MB, yang menempatkan batas pada ukuran maksimum pesan yang diizinkan saat menerima. DefaultnyamaxReceivedMessageSize
adalah 64 KB, yang biasanya terlalu rendah untuk skenario streaming. Atur pengaturan kuota ini sesuai ukuran maksimum pesan yang diharapkan diterima aplikasi Anda. Perhatikan juga bahwamaxBufferSize
mengontrol ukuran maksimum yang di-buffer, dan atur dengan tepat.Cuplikan konfigurasi berikut dari sampel menunjukkan pengaturan properti
TransferMode
ke streaming padabasicHttpBinding
dan pengikatan HTTP kustom.<basicHttpBinding> <binding name="HttpStreaming" maxReceivedMessageSize="67108864" transferMode="Streamed"/> </basicHttpBinding> <!-- an example customBinding using Http and streaming--> <customBinding> <binding name="Soap12"> <textMessageEncoding messageVersion="Soap12WSAddressing10" /> <httpTransport transferMode="Streamed" maxReceivedMessageSize="67108864"/> </binding> </customBinding>
Cuplikan kode berikut menunjukkan pengaturan properti
TransferMode
ke streaming padabasicHttpBinding
dan pengikatan HTTP kustom.public static Binding CreateStreamingBinding() { BasicHttpBinding b = new BasicHttpBinding(); b.TransferMode = TransferMode.Streamed; return b; }
Public Shared Function CreateStreamingBinding() As Binding Dim b As New BasicHttpBinding() b.TransferMode = TransferMode.Streamed Return b End Function
Cuplikan kode berikut menunjukkan pengaturan properti
TransferMode
ke streaming pada pengikatan TCP kustom.public static Binding CreateStreamingBinding() { TcpTransportBindingElement transport = new TcpTransportBindingElement(); transport.TransferMode = TransferMode.Streamed; BinaryMessageEncodingBindingElement encoder = new BinaryMessageEncodingBindingElement(); CustomBinding binding = new CustomBinding(encoder, transport); return binding; }
Public Shared Function CreateStreamingBinding() As Binding Dim transport As New TcpTransportBindingElement() transport.TransferMode = TransferMode.Streamed Dim binding As New CustomBinding(New BinaryMessageEncodingBindingElement(), _ transport) Return binding End Function
Operasi
GetStream
,UploadStream
, danEchoStream
semua berurusan dengan pengiriman data langsung dari file atau menyimpan data yang diterima langsung ke file. Kode berikut adalah untukGetStream
.public Stream GetStream(string data) { //this file path assumes the image is in // the Service folder and the service is executing // in service/bin string filePath = Path.Combine( System.Environment.CurrentDirectory, ".\\..\\image.jpg"); //open the file, this could throw an exception //(e.g. if the file is not found) //having includeExceptionDetailInFaults="True" in config // would cause this exception to be returned to the client try { FileStream imageFile = File.OpenRead(filePath); return imageFile; } catch (IOException ex) { Console.WriteLine( String.Format("An exception was thrown while trying to open file {0}", filePath)); Console.WriteLine("Exception is: "); Console.WriteLine(ex.ToString()); throw ex; } }
Public Function GetStream(ByVal data As String) As Stream Implements IStreamingSample.GetStream 'this file path assumes the image is in ' the Service folder and the service is executing ' in service/bin Dim filePath = Path.Combine(System.Environment.CurrentDirectory, ".\..\image.jpg") 'open the file, this could throw an exception '(e.g. if the file is not found) 'having includeExceptionDetailInFaults="True" in config ' would cause this exception to be returned to the client Try Return File.OpenRead(filePath) Catch ex As IOException Console.WriteLine(String.Format("An exception was thrown while trying to open file {0}", filePath)) Console.WriteLine("Exception is: ") Console.WriteLine(ex.ToString()) Throw ex End Try End Function
Menulis stream kustom
Untuk melakukan pemrosesan khusus pada setiap potongan aliran data saat dikirim atau diterima, dapatkan kelas stream kustom dari Stream. Sebagai contoh stream kustom, kode berikut berisi metode
GetReversedStream
dan kelasReverseStream
.GetReversedStream
membuat dan menampilkan instans baruReverseStream
. Pemrosesan aktual terjadi saat sistem membaca dari objekReverseStream
. MetodeReverseStream.Read
ini membaca potongan byte dari file yang mendasarinya, membaliknya, lalu menampilkan byte terbalik. Metode ini tidak membalikkan seluruh konten file; hanya membalikkan satu potongan byte pada satu waktu. Contoh ini menunjukkan cara melakukan pemrosesan streaming saat konten sedang dibaca atau ditulis dari stream.class ReverseStream : Stream { FileStream inStream; internal ReverseStream(string filePath) { //opens the file and places a StreamReader around it inStream = File.OpenRead(filePath); } public override bool CanRead { get { return inStream.CanRead; } } public override bool CanSeek { get { return false; } } public override bool CanWrite { get { return false; } } public override void Flush() { throw new Exception("This stream does not support writing."); } public override long Length { get { throw new Exception("This stream does not support the Length property."); } } public override long Position { get { return inStream.Position; } set { throw new Exception("This stream does not support setting the Position property."); } } public override int Read(byte[] buffer, int offset, int count) { int countRead = inStream.Read(buffer, offset, count); ReverseBuffer(buffer, offset, countRead); return countRead; } public override long Seek(long offset, SeekOrigin origin) { throw new Exception("This stream does not support seeking."); } public override void SetLength(long value) { throw new Exception("This stream does not support setting the Length."); } public override void Write(byte[] buffer, int offset, int count) { throw new Exception("This stream does not support writing."); } public override void Close() { inStream.Close(); base.Close(); } protected override void Dispose(bool disposing) { inStream.Dispose(); base.Dispose(disposing); } void ReverseBuffer(byte[] buffer, int offset, int count) { int i, j; for (i = offset, j = offset + count - 1; i < j; i++, j--) { byte currenti = buffer[i]; buffer[i] = buffer[j]; buffer[j] = currenti; } } }
Friend Class ReverseStream Inherits Stream Private inStream As FileStream Friend Sub New(ByVal filePath As String) 'opens the file and places a StreamReader around it inStream = File.OpenRead(filePath) End Sub Public Overrides ReadOnly Property CanRead() As Boolean Get Return inStream.CanRead End Get End Property Public Overrides ReadOnly Property CanSeek() As Boolean Get Return False End Get End Property Public Overrides ReadOnly Property CanWrite() As Boolean Get Return False End Get End Property Public Overrides Sub Flush() Throw New Exception("This stream does not support writing.") End Sub Public Overrides ReadOnly Property Length() As Long Get Throw New Exception("This stream does not support the Length property.") End Get End Property Public Overrides Property Position() As Long Get Return inStream.Position End Get Set(ByVal value As Long) Throw New Exception("This stream does not support setting the Position property.") End Set End Property Public Overrides Function Read(ByVal buffer() As Byte, _ ByVal offset As Integer, _ ByVal count As Integer) As Integer Dim countRead = inStream.Read(buffer, _ offset, _ count) ReverseBuffer(buffer, _ offset, _ countRead) Return countRead End Function Public Overrides Function Seek(ByVal offset As Long, _ ByVal origin As SeekOrigin) As Long Throw New Exception("This stream does not support seeking.") End Function Public Overrides Sub SetLength(ByVal value As Long) Throw New Exception("This stream does not support setting the Length.") End Sub Public Overrides Sub Write(ByVal buffer() As Byte, _ ByVal offset As Integer, _ ByVal count As Integer) Throw New Exception("This stream does not support writing.") End Sub Public Overrides Sub Close() inStream.Close() MyBase.Close() End Sub Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean) inStream.Dispose() MyBase.Dispose(disposing) End Sub Private Sub ReverseBuffer(ByVal buffer() As Byte, _ ByVal offset As Integer, _ ByVal count As Integer) Dim i = offset Dim j = offset + count - 1 Do While i < j Dim currenti = buffer(i) buffer(i) = buffer(j) buffer(j) = currenti i += 1 j -= 1 Loop End Sub End Class