Csla.Server.IDataPortalServer in VB.NET

Make PDF-417 2d barcode in VB.NET Csla.Server.IDataPortalServer

Each channel comes in two parts: a proxy on the client and a host on the server. Csla.DataPortal calls the proxy, which in turn transfers the call to the host by using its channel. The host then delegates the call to a Csla.Server.DataPortal object. To ensure that all the parts of this chain can reliably interact, there are two interfaces: Csla.Server.IDataPortalServer and Csla. DataPortalClient.IDataPortalProxy.

The IDataPortalServer interface defines the methods common across the entire process: Public Interface IDataPortalServer Function Create( _ ByVal objectType As Type, _ ByVal criteria As Object, _ ByVal context As DataPortalContext) Function Fetch( _ ByVal criteria As Object, _ ByVal context As DataPortalContext) Function Update( _ ByVal obj As Object, _ ByVal context As DataPortalContext) Function Delete( _ ByVal criteria As Object, _ ByVal context As DataPortalContext) End Interface

Notice that these are the same method signatures as implemented by the methods in Csla.DataPortal, making it very easy for that class to delegate its calls through a proxy and host all the way to Csla.Server.DataPortal.

All the proxy classes implement a common Csla.DataPortalClient.IDataPortalProxy interface so they can be used by Csla.DataPortal. This interface inherits from Csla.Server.IDataPortalServer, ensuring that all proxy classes will have the same methods as all server-side host classes: Public Interface IDataPortalProxy Inherits Server.IDataPortalServer ReadOnly Property IsServerRemote() As Boolean End Interface In addition to the four data methods, proxy classes need to report whether they interact with an actual server-side host or not. As you ll see, at least one proxy interacts with a client-side host. Recall that in Csla.DataPortal, the IsServerRemote property was used to control whether the context data was set and restored. If the server-side code is running inside the client process, then much of that work can be bypassed, improving performance.

The default option for a network channel is not to use the network at all, but rather to run the server-side code inside the client process. This option offers the best performance, though possibly at the cost of security or scalability. The various trade-offs of n-tier deployments were discussed in 1. Even when running the server-side code in-process on the client, the data portal uses a proxy for the local channel : Csla.DataPortalClient.LocalProxy. As with all proxy classes, this one implements the Csla.DataPortalClient.IDataPortalProxy interface, exposing a standard set of methods and properties for use by Csla.DataPortal. Because this proxy doesn t actually use a network protocol, it is the simplest of all the proxies:

Public Class LocalProxy Implements DataPortalClient.IDataPortalProxy Private mPortal As Server.IDataPortalServer = _ New Server.DataPortal Public Function Create( _ ByVal objectType As System.Type, ByVal criteria As Object, _ ByVal context As Server.DataPortalContext) As Server.DataPortalResult _ Implements Server.IDataPortalServer.Create Return mPortal.Create(objectType, criteria, context) End Function Public Function Fetch( _ ByVal criteria As Object, _ ByVal context As Server.DataPortalContext) As Server.DataPortalResult _ Implements Server.IDataPortalServer.Fetch Return mPortal.Fetch(criteria, context) End Function Public Function Update( _ ByVal obj As Object, _ ByVal context As Server.DataPortalContext) As Server.DataPortalResult _ Implements Server.IDataPortalServer.Update Return mPortal.Update(obj, context) End Function Public Function Delete( _ ByVal criteria As Object, _ ByVal context As Server.DataPortalContext) As Server.DataPortalResult _ Implements Server.IDataPortalServer.Delete Return mPortal.Delete(criteria, context) End Function Public ReadOnly Property IsServerRemote() As Boolean _ Implements IDataPortalProxy.IsServerRemote Get Return False End Get End Property End Class All this proxy does is directly create an instance of Csla.Server.DataPortal: Private mPortal As Server.IDataPortalServer = _ New Server.DataPortal Each of the data methods (Create(), Fetch(), etc.) simply delegates to this object. The result is that the client call is handled by a Csla.Server.DataPortal object running within the client AppDomain and on the client s thread. Due to this, the IsServerRemote property returns False.

More interesting is the .NET Remoting channel. This is implemented on the client by the RemotingProxy class, and on the server by the RemotingPortal class. When Csla.DataPortal delegates a call into RemotingProxy, it uses .NET Remoting to pass that call to a RemotingPortal object on the server. That object then delegates the call to a Csla.Server.DataPortal object. Because .NET Remoting automatically serializes objects across the network, the RemotingProxy class is not much more complex than LocalProxy: Public Class RemotingProxy Implements DataPortalClient.IDataPortalProxy #Region " Configure Remoting " Shared Sub New() ' create and register a custom HTTP channel ' that uses the binary formatter Dim properties As New Hashtable properties("name") = "HttpBinary" If ApplicationContext.AuthenticationType = "Windows" Then ' make sure we pass the user's Windows credentials ' to the server properties("useDefaultCredentials") = True End If Dim formatter As New BinaryClientFormatterSinkProvider Dim channel As New HttpChannel(properties, formatter, Nothing) ChannelServices.RegisterChannel(channel, EncryptChannel) End Sub Private Shared ReadOnly Property EncryptChannel() As Boolean Get Dim encrypt As Boolean = _ (ConfigurationManager.AppSettings("CslaEncryptRemoting") = "true") Return encrypt End Get End Property #End Region Private mPortal As Server.IDataPortalServer Private ReadOnly Property Portal() As Server.IDataPortalServer Get If mPortal Is Nothing Then mPortal = CType( _ Activator.GetObject(GetType(Server.Hosts.RemotingPortal), _ ApplicationContext.DataPortalUrl.ToString), _ Server.IDataPortalServer) End If Return mPortal End Get End Property