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IUnknown
In computer programming, the IUnknown interface is the fundamental interface in the Component Object Model (COM). The COM specification mandates that COM objects must implement this interface. Furthermore, every other COM interface must be derived from IUnknown. IUnknown exposes two essential features of all COM objects: object lifetime management through reference counting, and access to object functionality through other interfaces. An IUnknown (or IUnknown-derived) interface consists of a pointer to a virtual method table that contains a list of pointers to the functions that implement the functions declared in the interface, in the order that they are declared in the interface. The in-process invocation call overhead is therefore identical to virtual method calls in C++. Methods The IUnknown interface exposes three methods: QueryInterface, AddRef, and Release:
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IDispatch
IDispatch is the interface that exposes the OLE Automation protocol. Extending IUnknown, it is one of the standard interfaces that can be exposed by COM objects. COM distinguishes between three interface types: ''custom'' that are VTABLE-based IUnknown interfaces, ''dispatch'' that are IDispatch interfaces supporting introspection, and ''dual'' interfaces supporting both types. The Automation (IDispatch) interface allows a client application to find out what properties and methods are supported by an object at run-time, i.e. implements the concept of RTTI. It also provides the information necessary to invoke these properties and methods. Client applications do not need to be aware of the object members when they are compiled. This allows COM and ActiveX objects to be called by scripting programs platforms such as the ASP server and JavaScript on Internet Explorer, where calling conventions were not known at the time IIS or IE were built. By contrast, a simple object library is ...
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Object Linking And Embedding
Object Linking & Embedding (OLE) is a proprietary technology developed by Microsoft that allows embedding and linking to documents and other objects. For developers, it brought OLE Control Extension (OCX), a way to develop and use custom user interface elements. On a technical level, an OLE object is any object that implements the IOleObject interface, possibly along with a wide range of other interfaces, depending on the object's needs. Overview OLE allows an editing application to export part of a document to another editing application and then import it with additional content. For example, a desktop publishing system might send some text to a word processor or a picture to a bitmap editor using OLE. The main benefit of OLE is to add different kinds of data to a document from different applications, like a text editor and an image editor. This creates a Compound File Binary Format document and a master file to which the document makes reference. Changes to data in the maste ...
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IOleObject
Object Linking & Embedding (OLE) is a proprietary technology developed by Microsoft that allows embedding and linking to documents and other objects. For developers, it brought OLE Control Extension (OCX), a way to develop and use custom user interface elements. On a technical level, an OLE object is any object that implements the IOleObject interface, possibly along with a wide range of other interfaces, depending on the object's needs. Overview OLE allows an editing application to export part of a document to another editing application and then import it with additional content. For example, a desktop publishing system might send some text to a word processor or a picture to a bitmap editor using OLE. The main benefit of OLE is to add different kinds of data to a document from different applications, like a text editor and an image editor. This creates a Compound File Binary Format document and a master file to which the document makes reference. Changes to data in the ma ...
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Globally Unique Identifier
A universally unique identifier (UUID) is a 128-bit label used for information in computer systems. The term globally unique identifier (GUID) is also used. When generated according to the standard methods, UUIDs are, for practical purposes, unique. Their uniqueness does not depend on a central registration authority or coordination between the parties generating them, unlike most other numbering schemes. While the probability that a UUID will be duplicated is not zero, it is generally considered close enough to zero to be negligible. Thus, anyone can create a UUID and use it to identify something with near certainty that the identifier does not duplicate one that has already been, or will be, created to identify something else. Information labeled with UUIDs by independent parties can therefore be later combined into a single database or transmitted on the same channel, with a negligible probability of duplication. Adoption of UUIDs is widespread, with many computing platform ...
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ActiveX
ActiveX is a deprecated software framework created by Microsoft that adapts its earlier Component Object Model (COM) and Object Linking and Embedding (OLE) technologies for content downloaded from a network, particularly from the World Wide Web. Microsoft introduced ActiveX in 1996. In principle, ActiveX is not dependent on Microsoft Windows operating systems, but in practice, most ActiveX controls only run on Windows. Most also require the client to be running on an x86-based computer because ActiveX controls contain compiled code. ActiveX is still supported as of Windows 10 through Internet Explorer 11, while ActiveX is not supported in their default web browser Microsoft Edge (which has a different, incompatible extension system, as it is based on Google's Chromium project). ActiveX controls ActiveX was one of the major technologies used in component-based software engineering. Compared with JavaBeans, ActiveX supports more programming languages, but JavaBeans supports m ...
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picture info

Reference Counting
In computer science, reference counting is a programming technique of storing the number of references, pointers, or handles to a resource, such as an object, a block of memory, disk space, and others. In garbage collection algorithms, reference counts may be used to deallocate objects that are no longer needed. Advantages and disadvantages The main advantage of the reference counting over tracing garbage collection is that objects are reclaimed ''as soon as'' they can no longer be referenced, and in an incremental fashion, without long pauses for collection cycles and with clearly defined lifetime of every object. In real-time applications or systems with limited memory, this is important to maintain responsiveness. Reference counting is also among the simplest forms of memory management to implement. It also allows for effective management of non-memory resources such as operating system objects, which are often much scarcer than memory (tracing garbage collection systems ...
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Globally Unique Identifier
A universally unique identifier (UUID) is a 128-bit label used for information in computer systems. The term globally unique identifier (GUID) is also used. When generated according to the standard methods, UUIDs are, for practical purposes, unique. Their uniqueness does not depend on a central registration authority or coordination between the parties generating them, unlike most other numbering schemes. While the probability that a UUID will be duplicated is not zero, it is generally considered close enough to zero to be negligible. Thus, anyone can create a UUID and use it to identify something with near certainty that the identifier does not duplicate one that has already been, or will be, created to identify something else. Information labeled with UUIDs by independent parties can therefore be later combined into a single database or transmitted on the same channel, with a negligible probability of duplication. Adoption of UUIDs is widespread, with many computing platform ...
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Windows Runtime
Windows Runtime (WinRT) is a platform-agnostic component and application architecture first introduced in Windows 8 and Windows Server 2012 in 2012. It is implemented in C++ and officially supports development in C++ (via C++/WinRT, C++/CX or WRL), Rust/WinRT, Python/WinRT, JavaScript- TypeScript, and the managed code languages C# and Visual Basic .NET (VB.NET). WinRT is not a runtime in a traditional sense but rather a language-independent application binary interface based on COM to allow APIs to be consumed from multiple languages, with services usually provided by a full-blown runtime, such as type activation. Apps using the Windows Runtime may run inside a sandboxed environment to allow greater security and stability and can natively support both x86 and ARM. WinRT components are designed with interoperability among multiple languages and APIs in mind, including native, managed and scripting languages. Built-in APIs provided by Windows which use the WinRT ABI are c ...
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IInspectable
Windows Runtime (WinRT) is a platform-agnostic component and application architecture first introduced in Windows 8 and Windows Server 2012 in 2012. It is implemented in C++ and officially supports development in C++ (via C++/WinRT, C++/CX or WRL), Rust/WinRT, Python/WinRT, JavaScript-TypeScript, and the managed code languages C# and Visual Basic .NET (VB.NET). WinRT is not a runtime in a traditional sense but rather a language-independent application binary interface based on COM to allow APIs to be consumed from multiple languages, with services usually provided by a full-blown runtime, such as type activation. Apps using the Windows Runtime may run inside a sandboxed environment to allow greater security and stability and can natively support both x86 and ARM. WinRT components are designed with interoperability among multiple languages and APIs in mind, including native, managed and scripting languages. Built-in APIs provided by Windows which use the WinRT ABI are commo ...
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Browser Helper Object
A Browser Helper Object (BHO) is a DLL module designed as a plugin for the Microsoft Internet Explorer web browser to provide added functionality. BHOs were introduced in October 1997 with the release of version 4 of Internet Explorer. Most BHOs are loaded once by each new instance of Internet Explorer. However, in the case of Windows Explorer, a new instance is launched for each window. BHOs are still supported as of Windows 10, through Internet Explorer 11, while BHOs are not supported in Microsoft Edge. Implementation Each time a new instance of Internet Explorer starts, it checks the Windows Registry for the key ''HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects''. If Internet Explorer finds this key in the registry, it looks for a CLSID key listed below the key. The CLSID keys under Browser Helper Objects tell the browser which BHOs to load. Removing the registry key prevents the BHO from being loaded. For each CLSID that is ...
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IObjectWithSite
A Browser Helper Object (BHO) is a DLL module designed as a plugin for the Microsoft Internet Explorer web browser to provide added functionality. BHOs were introduced in October 1997 with the release of version 4 of Internet Explorer. Most BHOs are loaded once by each new instance of Internet Explorer. However, in the case of Windows Explorer, a new instance is launched for each window. BHOs are still supported as of Windows 10, through Internet Explorer 11, while BHOs are not supported in Microsoft Edge. Implementation Each time a new instance of Internet Explorer starts, it checks the Windows Registry for the key ''HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects''. If Internet Explorer finds this key in the registry, it looks for a CLSID key listed below the key. The CLSID keys under Browser Helper Objects tell the browser which BHOs to load. Removing the registry key prevents the BHO from being loaded. For each CLSID that is ...
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OLE Automation
In Microsoft Windows applications programming, OLE Automation (later renamed to simply Automation) is an inter-process communication mechanism created by Microsoft. It is based on a subset of Component Object Model (COM) that was intended for use by scripting languages – originally Visual Basic – but now is used by several languages on Windows. All automation objects are required to implement the IDispatch interface. It provides an infrastructure whereby applications called ''automation controllers'' can access and manipulate (i.e. set properties of or call methods on) shared ''automation objects'' that are exported by other applications. It supersedes Dynamic Data Exchange (DDE), an older mechanism for applications to control one another. As with DDE, in OLE Automation the automation controller is the "client" and the application exporting the automation objects is the "server". Contrary to its name, automation objects do not necessarily use Microsoft OLE, although ...
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