“TCP/IP - Transmission Control Protocol / Internet Protocol”


Definition: Transmission Control Protocol (TCP) and Internet Protocols (IP) are two distinct network protocols, technically speaking. TCP and IP are so commonly used together, however, that TCP/IP has become standard terminology to refer to either or both of the protocols.IP corresponds to the Network layer (Layer 3) in the OSI Model, whereas TCP corresponds to the Transport layer (Layer 4) in OSI. In other words, the term TCP/IP refers to network communications where the TCP transport is used to deliver data across IP networks.
The average person on the Internet works in a predominately TCP/IP environment. Web browsers, for example, use TCP/IP to communicate with Web servers.
Also Known As: Transmission Control Protocol / Internet Protocol.
IP Addresses are the fundamental method for computers to identify themselves on most computer networks. Every computer (or other network device) connected to the Internet has an IP address. This tutorial explains the basics of finding, changing, and hiding (your) my IP addresses.
Inside IP Addresses
IP addresses are written in a notation using numbers separated by dots. This is called “dotted-decimal” notation. Examples of IP addresses in dotted-decimal notation are 10.0.0.1 and 192.168.0.1 although many millions of different IP addresses exist.
Finding IP Addresses
Everyone who needs to use a computer network should understand how to look up their own IP addresses. The exact procedure to follow depends on the kind of computer you use. Additionally, in some situations you may need to find the IP address of someone else’s computer.
Fixing IP Address Problems
When a computer network is functioning properly, IP addresses stay in the background and don’t require any specific attention. However, some common problems you may encounter when setting up or joining a computer network include:
A computer has no IP address
Two computers have the same IP address
A computer has a “bad” IP address that won’t allow it to “talk” on the network
To solve these problems, several techniques can be applied including IP address release / renew, setting static IP addresses, and updating the subnet ccnfiguration

Top 8 GIS / Charting / Mapping Delphi Tools and Components

If you’re looking for the best Delphi GIS, charting and mapping tools, look no further. The following list presents the most popular picks for all your charting and plotting needs. In most cases the tools come as VCL libraries and offer more than you can think of.

1. TatukGIS Developer Kernel

A comprehensive GIS development toolkit provided as a native Delphi/C++Buider VCL. This product supports most GIS/CAD and raster image formats, most SQL database products, and approximately 2,300 functions and properties for development of even the most advanced GIS solutions.

Vendor’s Site

2. teeChart Pro

TeeChart Pro provides complete, quick and easy to use charting and plotting ActiveX COM and Borland VCL / CLX classes for Business, Real-Time, Financial and Scientific applications. 100% Source code included. Hundreds of Graph styles in 2D and 3D, 24 mathematical and statistical Functions, Data Aware both at design and run-time, photo realistic 3D OpenGL, …

Vendor’s Site

3. ProEssentials

GigaSoft ProEssentials is a set of charting components for Windows development. ProEssentials includes a charting ActiveX solution for Visual Basic and other software development environments that can utilize ActiveX/ COM objects. ProEssentials is also a charting VCL solution for Delphi and Builder. Example code/projects are included for Visual Basic, Visual C, Delphi, and Builder.

Vendor’s Site

4. ExpressOrgChart Suite

The ExpressOrgChart is a fully functional VCL component (both data aware and non data aware), designed for the display and editing of hierarchical tree data structures such as the contents of a book or file system on a disc. Each node of the chart can have a limitless number of children, displayed horizontally, directly below a given node.

Vendor’s Site

5. Graphics Server

Graphics Server’s advanced data features let you chart up to 128,000 dynamic data points in a single graph; add curve-fitting, error bars, and trend lines to all log and linear graph variants; and even plot incoming data in real time. Graphics Server offers multiple platforms, multiple hosts, multiple interfaces, the most extensive range of graphs, charts and statistical functions available.

Vendor’s Site

6. MapObjects

MapObjects software is a powerful collection of embeddable mapping and GIS components. Developers can use MapObjects to create applications that include dynamic live maps and GIS capabilities.With MapObjects you can: Add mapping components to enhance existing applications; Build lightweight data viewing applications; Create customized mapping and GIS programs that fulfill specific tasks.

Vendor’s Site

7. Component One Chart

Easily create 2D and 3D charts in minutes and distribute them royalty-free. Choose from a wide variety of chart types, and get all the robust, time-saving, easy-to-use features you expect, such as data binding to any data source, often without writing a line of code; built-in zooming, scaling, and rotating; and intelligent update for fast, real-time charting and tracking.

Vendor’s Site

8. SDL Component Suite

Collection of components supporting scientific and engineering computing. The entire suite consists of about 30 units covering a wide range of requirements in science and engineering.

Vendor’s Site

Display a LogIn / Password Dialog Before the Main Form is Created (Delphi)

The MainForm of a Delphi application is a form (window) that is the first one created in the main body of the application.

If you need to implement some kind of authorization for your Delphi application you might want to display a login / password dialog *before* the main form is created and displayed to the user.

In short, the idea would be to create, display, and destroy the “login” dialog before creating the main form.

The Delphi MainForm

When a new Delphi project is created, “Form1″ automatically becomes the value of the MainForm property (of the global Application object). To assign a different form to the MainForm property, use the Forms page of the Project|Options dialog box at design time.When the main form closes, the application terminates.

Login/Password Dialog

Let’s start by creating the main form of the application.

Create a new Delphi project containing one form. This form is, by design, the main form.

If you change the name of the form to “TMainForm” and save the unit as “main.pas”, the project’s source code looks like (the project was saved as “PasswordApp”):

program PasswordApp;

uses
Forms,
main in ‘main.pas’ {MainForm};

{$R *.res}

begin
Application.Initialize;
Application.CreateForm(TMainForm, MainForm) ;
Application.Run;
end.

Now, add a second form to the project.

By design, the second form added, gets listed in the “Auto-Create Forms” list on the Project Options dialog.

Name the second form “TLoginForm” and *remove* ir from the “Auto-Create Forms” list. Save the unit as “login.pas”.

Add a Label, an Edit and a Button on the form.

Add a class method to create, show and close the login/password dialog. The method “Execute” returns true if the user has entered the correct password in the password edit box.

Here’s the full source code:

unit login;

interface

uses
Windows, Messages, SysUtils, Variants, Classes,
Graphics, Controls, Forms, Dialogs, StdCtrls;

type
TLoginForm = class(TForm)
LogInButton: TButton;
pwdLabel: TLabel;
passwordEdit: TEdit;
procedure LogInButtonClick(Sender: TObject) ;
procedure FormCreate(Sender: TObject) ;
public
class function Execute : boolean;
end;

implementation
{$R *.dfm}

class function TLoginForm.Execute: boolean;
begin
with TLoginForm.Create(nil) do
try
Result := ShowModal = mrOk;
finally
Free;
end;
end;

procedure TLoginForm.LogInButtonClick(Sender: TObject) ;
begin
if passwordEdit.Text = ‘delphi’ then
ModalResult := mrOK
else
ModalResult := mrAbort;
end;

end.

The Execute method dynamically creates an instance of the TLoginForm and displays it modaly using the ShowModal method.

ShowModal does not return until the form closes. When the form closes, it returns the value of the ModalResult property.

The “LogInButton” OnClick event handler assigns “mrOk” to the ModalResult property is the user has entered the correct password (’delphi’ in the above example). If the user has provided a wrong password, ModalResult is set to “mrAbort” (can be anything *except* “mrNone”).

Setting a value to the ModalResult property closes the form … Execute returns true is ModalResult equals “mrOk” - if the user has entered the correct password.

Don’t Create MainForm Before Login

You now only need to make sure the main form is not created if the user failed to provide the correct password.

Here’s how the project’s source code should look :

program PasswordApp;

uses
Forms,
main in ‘main.pas’ {MainForm},
login in ‘login.pas’ {LoginForm};

{$R *.res}

begin
if TLoginForm.Execute then
begin
Application.Initialize;
Application.CreateForm(TMainForm, MainForm) ;
Application.Run;
end
else
begin
Application.MessageBox(’You are not authorized to use the application. The password is “delphi”.’, ‘Password Protected Delphi application’) ;
end;
end.

Note the usage of the if then else block to determine if the main form should be created. If “Execute” returns false, MainForm is not created and the application terminates without starting, so to say.

That’s all!

Thank You….