Component object model pdf download

Carousel Previous Carousel Next. Construction Foreman or Superintendent or Project Manager. Jump to Page. Search inside document. Prerequisites If you are a software developer who would like to build the Keysticks application, you will need to install the following prerequisites: 1. Contents of this source distribution The Keysticks. The source distribution also contains the following folders: - Data Local data folder that is used by the application when run from its build location i.

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Download Microsoft Edge More info. Contents Exit focus mode. Please rate your experience Yes No. Any additional feedback? In this article. The layout of the objects refers to the way in which the binary memory map which points to the functions is represented in memory.

In DCOM the equivalent is the interface map. By following these guidelines a developer has the choice of any language which is capable of making use of pointers. DCOM components make extensive use of pointers in the interface map and this is why it is important for the language to provide support for pointers.

Below is a pictorial representation of how the pointers link up between the component, the interface map and the actual function itself. This in itself introduces problems regarding reference counting but the DCOM concept of interfaces manages to solve this problem.

An IPID however does not indicate the binding information necessary to carry out the actual invocation. Each machine has a unique object export service to coordinate the management of all OXID's on that machine. It caches and returns to clients on request the string bindings necessary to connect to OXIDs of exported objects. It also receives pings described below from remote clients to keep its own objects alive. The DCOM protocol provides for remote reference counting as well as pinging.

Reference counting will be inadequate in cases where clients terminate abnor- mally. Remote abnormal termination is detected by periodic pings. This allows a DCOM interface to be represented in a lan- guage independent manner. IAccInfo , the interface name is a valid data type and as such can be used as a parameter within a method declarations, this provides for static type checking during the MIDL compile phase.

As clients gain access to an object, AddRef is called, this increments the reference counter. When a client no longer requires access, Release is called, decrementing the counter. Once the a client has a pointer to the object's IUnknown interface, it can use QueryInterface to request pointers to other interfaces.

The facility for asynchronous method calls is provided as part of the DCOM standard. Indeed, both support the development of distributed object systems. It is worth noting that both technologies are still in their infancy. DCOM was made available in late This selection encompasses both dynamically and statically typed languages.

Because of this, DCOM may in some instances provide better performance in local environments, as it does not have to deal with many of the complexities of a true multi-language environment. However, many CORBA implementations also provide automatic short cuts for local environments by providing the object's actual address in- stead of a proxy handle. The result of registering the class can be seen by running regedit interactively.

The server code starts by creating a class, in our example called CCar4, which inherits from IPersist. Normally classes implement one of the derived classes and not IPersist. CreateInstance accepts three parameters, an IUnknown pointer, a reference to the interface required which are both in parameters, and an indirect pointer to the interface itself. This third parameter will contain a pointer to the interface if the object is correctly instantiated. CreateInstance will create an object of the type requested and then query that object for to a pointer the requested interface, which is then put into the out parameter.

LockServer, the other member function in the IClassFactory interface, deals with maintaining the factory object in memory even when currently not in use, making it quicker to instantiate objects.

This function is not often called on most ClassFactory objects. This object instance will be used to instantiate all Car objects while the server is running. The main function now calls CoRegisterClassObject which has four in param- eters, a CLSID identifying the class being registered, a pointer to the class fac- tories IUnknown interface, the context for execution and a connection ag. The last parameter is an out parameter that can be used to revoke the registration of the class object.

Now the server waits in a loop for incoming connections. Finally the server's main function calls CoUninitialize. This is done with the function CoCreateInstanceEx which takes six parameters. At this stage the reference counter on the Car object is two as we have two separate interfaces to the same Car object.

This would allow Release to be called once through one of the interfaces without removing the server. When AddRef is called on the IUnknown interface in the sample program, the reference counter is incremented to three. This function dynamically allocates memory to hold the string and therefore it is the caller's responsibility to release this mem- ory.

The function CoGetMalloc is used to get a pointer to the interface for the memory allocation object. Which is then used to free the memory. Finally the client calls Release twice to free the Car object. Heinz Schmidt of Monash University, who gave valuable comments and assistance. Brockschmidt, K. Inside OLE2. Microsoft Press. Microsoft Devel- opment Network Library.

Dobbs Journal and Microsoft Corporation , December. Dobbs Journal. IBM, C. OpenDoc vs. OLE 2. Technical report, IBM. Katiyar, D. OLE vs. Kindel, C. The Rules of the Component Object Model. Microsoft Development Network Library. Kruglinski, D.