Add terminal emulation to any .NET application or service with VT and Telnet controls.

Designed for Modern Applications

PowerTCP Emulation for .NET exposes a modern multi-threaded design with technical advantages over competing products.

Async Methods

The async methods (BeginXXX) seen in competing products reflect an antiquated single-threaded design model that denies the benefits of multi-threaded power. Please read on to see how PowerTCP Emulation for .NET delivers multi-threaded power to your application without adding the complexity that is often associated with multi-threading techniques.

Operation on the client side of the client/server model is inherently command driven, so Emulation for .NET provides a simple Start(delegate) method that executes the body of your delegate on a worker thread. This straight-forward concept provides a flexible technique for using PowerTCP in any application environment.

This design eliminates the need for BeginXXX methods and EndXXX events. There is a clean interface with one method for each function and several advantages are immediately realized:

Efficiency. Methods are designed to efficiently block on socket receive operations (the thread sleeps until bytes are received). This results in the most robust and efficient design possible.

Reusable code. Your delegate(s) can be used in applications both with and without a UI. It is no longer necessary to use BeginFoo for Windows Forms applications, and (the blocking) Foo for services, web applications and console applications.

Lower life-cycle cost. Code is written sequentially because there is no UI message pump to consider. It is not necessary to write code for numerous event handlers. Your code is self-documenting, easier to debug and maintain, and has a lower life-cycle cost.

Easy-to-implement parallel operation. Worker threads are easily spawned, supporting intensively parallel operations. Alternatively, serial operation is easily implemented by using just one thread. Flexibility of design is key.

No more state machine. It is not necessary to track state in event handlers. Take the simple case where the following sequence takes place:

  • Receive data R1
  • Send data S1
  • Receive data R2
  • Send data S2

Using BeginXXX, an event is raised when data is received and a state machine is required (if R1 is received then send S1, else if R2 is received then send S2). Using a single worker thread, the operation is coded in simple, declarative steps (Receive R1, Send S1, Receive R2, Send S2).

No More Pseudo-Blocking

Competing products use "pseudo-blocking" to process UI events while the method blocks. Without pseudo-blocking overhead methods are faster and more efficient. Also, re-entrancy problems (caused when UI messages are processes while a communication method is in progress) are no longer possible.

Developing Applications Without a UI

Developing console applications, web applications, services and other applications without a UI is as easy as ever. Sequential code performs efficiently. If parallel operation is desired, Start(delegate) can be used to execute code in any delegate body in parallel.

Developing Applications With a UI

Developing Windows Forms applications is now just as easy as writing applications without a UI. One method (the delegate) can be used in both types of applications. The only difference is that a UI app uses Start(delegate) to spawn a worker thread upon which the method executes, and any data needed by the UI must be marshaled to the UI thread. To this end, PowerTCP components include Start() and Marshal() convenience methods.

The Start Method

Use the Start method to execute one or more methods on a new worker thread, so the UI is not blocked during operation. The syntax for this method is simple:

telnet1.Start(myBlockingFunction, myObject);

private void myBlockingFunction(object myObject)

Marshaling Data

It is often necessary to pass information from a worker thread to update an element on the UI thread. Use the Marshal method for this purpose. Each Marshal overload is paired with an event that is raised on the UI thread.

//Read data, marshal to the UI thread
byte [] buffer = new byte [1024];
telnet1.Marshal(telnet1.Read(buffer), "", null);

private void telnet1_Data(object sender, DataEventArgs e)
    //Display received data
    //This event is raised on the UI thread

In the code above, the Telnet component reads and marshals data to the UI thread using the Marshal method and the Data event. An alternative technique may be used if data is displayed in the Vt control. The underlying Stream may be passed to the Vt control, which internally reads and displays incoming data without the need for explicit Read and Marshal calls.


Typical Use

The developer wants to execute a series of methods without interfering with the user-interface. A button, textbox, and the PowerTCP Telnet component are added to the form. Pressing the button will initiate a session which sends data to a telnet server. A log of the session is displayed in the textbox. The automateSession function, which can be reused in a non-UI application, is passed to Start and executes on a worker thread.

private void button1_Click(object sender, EventArgs e)
    //Event handlers were added in the designer
    //Start the process on a worker thread so the UI is not blocked
    telnet1.Start(automateSession, null);

private void automateSession(object notUsed)
    //This function executes on a worker thread

        //Login to the server, marshal data to the UI thread
        Data data = telnet1.Login(new Credentials("myUsername", "myPassword", "$"));
        telnet1.Marshal(data, "", null);

        //Send a list command
        telnet1.Write("ls -la\r");//Wait for prompt, marshal data to the UI thread
        telnet1.Marshal(telnet1.ReadToDelimiter("$"), "", null);

        //Send an exit command; server will close the connection

        //Read any remaining data before the shutdown
        telnet1.Marshal(telnet1.ReadToEnd(), "", null);
    catch (Exception ex)
        //Report errors to the UI thread

private void telnet1_Data(object sender, DataEventArgs e)
    //Add data received to the textbox

private void telnet1_Error(object sender, ErrorEventArgs e)
    //Add error messages to the textbox