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What is API? : 

What is API? Stands for Application Programming Interface Is an interface implemented by a software program to enable interaction with other software... Similar to the way a user interface facilitates interaction between humans and computers... It is specified in terms of a programming language that can be compiled when an application is built...

What is API?.................. : 

What is API?.................. The software that provides the functionlaity described by an API is said to be an implementation of the API... An API is often a part of a software Development kit(SDK). Generally, an API is system software for an operating system(environment) which consists of a standardized ser of functions and procedures. Programmers can call these functions and procedures from their programs to gain extra functionality.

Why API?? : 

Why API?? Because programmers do not have to write this code themselves, they save time. The system provides a standard and well documented way of working. It is possible to redesign or improve the functions within the API without breaking code that relies in it.

API Examples : 

API Examples Microsoft WIN32 API Java Platform, Enterprise Edition APIs OpenGL cross-platform API DirectX for Microsoft Windows Simple DirectMedia Player(SDL) Universal Home API Google Maps API Wikipedia API


WINDOWS 32 API Is a set of predefined Windows functions used to controll the appearance and behaviour of every Windows element . The system also provides a standard and well documented way of working. Every user action causes the execution of several or more API function telling windows what’s happened. is something like the native code of windows.

WINDOWS 32 API...... : 

WINDOWS 32 API...... Microsoft Windows API come with the operating system for anyone to use. Software for embedded systems such as video game console generaly falls into the application-integrated category. most of the Win32 API can be provided under a UNIX system using software called Wine.

WINDOWS 32 API...... : 

WINDOWS 32 API...... The API functions reside in DLLs (like User32.dll, GDI32.dll, Shell32.dll, ...) in the Windows system directory. Is designed for usage by C/C++ programs and is the most direct way to interact with a Windows system for software applications. A Software Development Kit (SDK) is available for Windows, which provides documentation and tools to enable developers to create software using the Windows API and associated Windows technologies.

WINDOWS 32 API...... : 

WINDOWS 32 API...... can be used by all sorts of programmers. Is a Lower level access to a Windows system. The Windows API is the set of functions and procedures available in Windows. The most often required functionality of the Windows API already exists in the VBScript basic development environment.

DLL(Dynamic Library) Files : 

DLL(Dynamic Library) Files is Microsoft's implementation of the shared library concept in the Microsoft Windows operating systems. These libraries usually have the file extension DLL, OCX (for libraries containing ActiveX controls), or DRV (for legacy system drivers). a library of executable functions or data that can be used by a Windows application. Typically, a DLL provides one or more particular functions and a program accesses the functions by creating either a static or dynamic link to the DLL.

DLL(Dynamic Library) Files.............. : 

DLL(Dynamic Library) Files.............. DLLs can also contain just data. A DLL can be used by several applications at the same time. Some DLLs are provided with the Windows operating system and available for any Windows application. Other DLLs are written for a particular application and are loaded with the application.

DLL Fundamentals.... : 

DLL Fundamentals.... DLL is created as a project that contains at least one source file and this source file should present an entry-point After creating the DLL, we have to build and distribute it so other programs can use it. When building it, we must create a library file that will accompany the DLL. This library file will be used by other programs to import what is available in the DLL.

DLL Fundamentals.... : 

DLL Fundamentals.... When the import library is created, it contains information about where each available function is included in the DLL and can locate it. When an application needs to use a function contained in the DLL, it presents its request to the import library. The import library checks the DLL for that function and uses the function if it exists.

Windows Messages... : 

Windows Messages... Messages are the basic way Windows tells our program that some kind of input has occurred and we must process it. A message to your form is sent when the user clicks on a button, moves the mouse over it or types text in a textbox. All messages are sent along with four parameters: A window handle, a message identifier and two 32-bit (Long) values.

Windows Messages... : 

Windows Messages... The window handle contains the handle of the window the message is going to. The identifier is actually the type of input occurred. All messages are sent along with four parameters: A window handle, a message identifier and two 32-bit (Long) values. Two values specify an additional information for the message (like where is the mouse cursor when the mouse is been moved).

Overview of the Windows API Components : 

Overview of the Windows API Components Base Services: Provide access to the fundamental resources available to a Windows system like file systems, devices, processes and threads, access to the Windows registry, and error handling. Graphics Device Interface: Provide the functionality for outputting graphical content to monitors, printers and other output devices.

Overview of the Windows API Components : 

Overview of the Windows API Components User Interface: Provides the functionality to create and manage screen windows and most basic controls, such as buttons and scrollbars, receive mouse and keyboard input, and other functionality associated with the GUI part of Windows. Common Dialog Box Library: Provides applications the standard dialog boxes for opening and saving files, choosing color and font, etc.

Overview of the Windows API Components : 

Overview of the Windows API Components Common Control Library: Gives applications access to some advanced controls provided by the operating system. These include things like status bars, progress bars, toolbars and tabs. Windows Shell: Component of the Windows API allows applications to access the functionality provided by the operating system shell, as well as change and enhance it.

Overview of the Windows API Components : 

Overview of the Windows API Components Network Services: Give access to the various networking capabilities of the operating system. Its sub-components include NetBIOS, Winsock, NetDDE, RPC and many others. Web APIs: The Internet Explorer web browser also exposes many APIs that are often used by applications, and as such could be considered a part of the Windows API.

Overview of the Windows API Components : 

Overview of the Windows API Components Multimedia related APIs: Microsoft has provided the (DirectX) set of APIs as part of every Windows installation since Windows 95 OSR2. DirectX provides a loosely related set of multimedia and gaming services, including: Direct3D: for access to 3D acceleration DirectSound:low level hardware accelerated sound DirectInput: for communication with input devices such as joysticks and gamepads. DirectPlay: as a multiplayer gaming infrastructure. DirectShow: which builds and runs generic multimedia pipelines DirectMusic:

API’s for interaction between programs : 

API’s for interaction between programs The Windows API mostly concerns itself with the interaction between the Operating System and an application. For communication between the different Windows applications among themselves, Microsoft has developed a series of technologies alongside the main Windows API. This started out with Dynamic Data Exchange (DDE), which was superseded by Object Linking and Embedding (OLE) and later by the Component Object Model (COM).

API Versions : 

API Versions Almost every new version of Microsoft Windows has introduced its own additions and changes to the Windows API. The name of the API however was kept consistent between different Windows version, and name changes were kept limited to major architectural and platform changes for Windows. Microsoft eventually changed the name of the then current Win32 API family into Windows API, and made it into a catch-all term for both past and future versions of the API. Win16, Win32, WIn32s, Win64


CONCLUSION The foresight to include APIs saves subsequent developers from having to find and review the source code. Braunstein says “APIs aren't difficult to create, but they can be difficult to learn.” Application developers and vendors must constantly be thinking about whether their APIs will be understandable to future developers. API is useless unless you document it....

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