ClientChannel Class

An application use a ClientChannel to send transactions, receive unsolicited data, and request other services from the NetServer or other custom made servers (see ServerChannel for details about building custom servers).

The communication channel is established as late as possible. Yet, once established, it is kept running until a system operator executes the "kill client" command in an NetServer Console. If the communication channel is lost for any other reason, it is automatically re-established as soon as possible.

In order to maximize reusability and to reduce the number of physical network connections, the ClientChannel communication link is implemented as a shared (multiplexed) channel. For this reason, a client application cannot use a ClientChannel directly, but it has to acquire a ClientSlot instance using the NewSlot method. It is through this ClientSlot that the client application communicates with the NetServer environment.

The following example uses a ClientChannel named SampleClient to obtain the date from a server called ACASER. This is accomplished by sending a transaction named ACA-TIME to the ACASER server. If an error occurs while processing this transaction, the reply code of the reply message will not be ACK. In this case, an exception is thrown with a message obtained from the Data of the reply message. If successful, the ClientSlot is released and the server's date is retrieved from a field called ACC_FECHA of the reply message and displayed in the system console.

using OBCOM.NetClient;

public class SampleClient
{
    public static void Main(string[] args)
    {
        // Create an OBCOM NetServer client named "CCLIENT"
        LayoutManager layouts = new LayoutManager("http://host/layouts/*.aspx");
        ClientChannel channel = ClientChannel.Create("CCLIENT", "net://host:10104", layouts);

        // Send transaction to "ACASER" server using a channel slot
        Message reply;
        using (ClientSlot slot = channel.NewSlot()) {
            reply = slot.SendTransaction("ACASER.ACA-TIME", null);
        }
        if (reply.ReplyCode != Message.Reply.ACK)
            throw new NetException(reply.Data);

        // Display the date contained in the "ACASER" reply message.
        System.Console.WriteLine("The reply date is " + reply.GetDate("ACC_FECHA"));
    }
}

Reference