What does QueryInterface do?

What does QueryInterface do?

QueryInterface is a mechanism in COM (microsoft’s Component Object Model) for determining if a known component supports a specific interface. You use the current interface pointer (usually IUnknown), and “query” the interface by passing an interface ID to it.

What is ADD ref?

You use AddRef to stabilize a copy of an interface pointer. It can also be called when the life of a cloned pointer must extend beyond the lifetime of the original pointer.

What is IUnknown interface?

IUnknown interface (unknwn. Enables clients to get pointers to other interfaces on a given object through the QueryInterface method, and manage the existence of the object through the AddRef and Release methods. All other COM interfaces are inherited, directly or indirectly, from IUnknown.

What is IDispatch interface?

The IDispatch interface was initially designed to support Automation. It provides a late-binding mechanism to access and retrieve information about an object’s methods and properties.

What is COM programming?

Component Object Model (COM) COM is a platform-independent, distributed, object-oriented system for creating binary software components that can interact. COM is the foundation technology for Microsoft’s OLE (compound documents) and ActiveX (Internet-enabled components) technologies.

What is Dispid?

The DISPID is the primary means of identifying a property or method and must be supplied to the Invoke function for a property or method to be invoked, along with an array of Variants containing the parameters.

What is OLE Automation in VB?

Automation (also called OLE automation) in Visual Basic is the process of controlling one program from another program or external development tool. You can automate any program that contains a Visual Basic object model.

What are COM calls?

COM manages method calls by assigning an identifier called a logical thread ID. A new one is assigned when a user selects a menu command or when the application initiates a new COM operation. Subsequent calls that relate to the initial COM call are assigned the same logical thread ID as the initial call.

What is COM dispatch identifier?

Specifies the COM dispatch identifier (DISPID) of a method, field, or property. This attribute contains the DISPID for the method, field, or property it describes. Unique DISPIDs are typically assigned by the common language runtime, but you can use this attribute to assign a specific DISPID to a method.

What’s the difference between OLE and COM?

OLE was a set of interfaces and data storage mechanisms to facilitate sharing data between applications. COM was the natural extension of using interfaces not only to share data, but runtime functionality – where the data was fronted by actual mechanisms to facilitate use.

Is OLE still used?

OLE is still alive. Not as active as it used to be. If you paste a picture into Word or Excel, you’re using OLE. Nothing has been deprecated–although Word and Excel don’t seem to like to support in place editing anymore.

Why are coders paid so high?

Programmers get paid so much for one reason and one reason only: because the demand is higher than the supply.

What is OLE used for?

OLE is a mechanism that allows users to create and edit documents containing items or “objects” created by multiple applications. OLE was originally an acronym for Object Linking and Embedding. However, it is now referred to as OLE. Parts of OLE not related to linking and embedding are now part of Active technology.

Why does OLE mean?

Olé is a Spanish interjection used to cheer on or praise a performance commonly used in bullfighting and flamenco dance.

What is DCOM and how it works?

DCOM is a programming construct that allows a computer to run programs over the network on a different computer as if the program was running locally. DCOM is an acronym that stands for Distributed Component Object Model.