Why is the ADO library a dynamic COM library? What does COM mean?
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Why is the ADO library a dynamic COM library? What does COM mean?
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The so -called Componet Object Model (component object model) is a specification that explains how to establish dynamic mutual components. This specification provides some binary and network standards that customers and components should follow. Through this standard, you can communicate between any two components without considering whether the operating environment it is in the same, whether the development language used is consistent, and whether it runs in the same computer.
COM's advantages?
First of all: users generally want to customize applications used, and component technology can be customized in essence, so users can use a certain component that they need to replace the original one. Secondly, since the component is an independent component of the relative application, we can use the same component in different programs without any problems, and the resolution of the software will be greatly enhanced. Third, with the increase of network bandwidth and its importance, distributed network applications have undoubtedly become increasingly important buying points in the software market. The component price structure can simplify the process of developing such applications.
What is COM ?
COM is not the simple upgrade of COM. The underlying structure of COM is still based on COM. It almost tolerates all the contents of COM. Combaded the technical elements such as COM, DCOM, and MTS. The layer is no longer the bottom -layer software structure. Through the various support of the operating system, the component object model is established on the application layer, leaving the underlying details of all components to the operating system. Essence
COM is no longer limited to COM component technology, it pays more attention to the design and implementation of distributed network applications. COM inherits almost all the advantages of COM, and at the same time avoid some of the shortcomings of COM's implementation. Combining the programming model of COM, DCOM, and MTS, inheriting most of their characteristics, adding new features to the original features, new ones have been added to new features. Function.
COM 's new advantages?
The main features of COM are listed below:
Com not only inherited all the advantages of COM, but also added some services. Such as queue service, load balance, memory database, event service, etc.
The queue service is very meaningful to distributed applications, especially when the network speed is very slow now, this mechanism can ensure that the application system can run reliable. When the application system contains a large number of nodes but the server is busy, the customer application can put their requests into the queue, and process these requests when the server load is relatively light;
is like COM Provide load balance services that can achieve dynamic load balance, and the load balance characteristics of the COM application do not need to write code to support. Customer programs and component programs can be implemented in a normal way. Obtaining the load balance characteristics is not implemented by programming, but the load balance of distributed applications is achieved through configuration. The queue service mentioned above actually reflects a load balance.
(1) Real asynchronous communication. COM the bottom layer provides queue component services, which allows customers and components to work together at different time points. COM applications can obtain such features without adding code.
(2) Event service. The new event mechanism makes the event source and event receiver more flexible. The system service is used to simplify the event model and avoid the trivial details of the COM connection object mechanism.
(3) Ejaculation. The scalability of COM is derived from multiple aspects. Dynamic load balance, and system services such as memory database, object pool, etc. provide a technical basis for the scalability of COM . Consistent.
(4) management and configurable. Management and configuration are the behavior of the development of the application system. Today, when the cost of software maintenance is increasing, COM applications will help software manufacturers and users to reduce investment in this area.
(5) Easy development. The complexity and difficulty of application development will determine the success of COM . Although the COM development model is more simplified than the previous COM component development, it really needs to be used to improve the development efficiency of development.
Com marks that Microsoft's component technology has reached a new height. It is no longer limited to a desktop system on a machine. Interconnected network. COM and multi -layer structure models and Windows operating systems provide a complete set of solutions for enterprise or web applications.
COM is Microsoft's invention. It claims that it can facilitate transplantation, version compatibility, all diseases, and longevity. As a result, a lot of DLL has filled the C drive
COM abbreviation is strictly encapsulated
. Others are the same as LS say, using Instance