Chapter 2 Framework plug-in Engine Design

The plug-in framework model is essentially an extension of application engineering. It implements the extension function through plug-ins and uses the framework for centralized and unified management. The framework provides the hostProgramCommunication between plug-ins and plug-ins. The plug-in framework can organically integrate extension plug-ins into a platform and work collaboratively effectively.

The plug-in framework model divides the functions of a program into relatively independent modules and stores the modules as plug-ins. These plug-ins, such as the same heap feature blocks, are built under a unified standard to become a complete, infinitely scalable application system.

Generally, a plug-in application framework consists of three components:

LHost Program: The Host Program of the plug-in framework is the dependent object of the plug-in. It consists of three parts: the main interface programEXEThe executable file format exists. It is responsible for parsing plug-in objects and entrusting and associating plug-in Object events to generate various buttons, tools, tool bars and menus.UIForm object; plug-in Engine (Plugin EngineIt parses the plug-in assembly, extracts the plug-in type information, generates the corresponding plug-in objects, and stores these plug-in objects in the plug-in collection and transfers them to the interface program for processing; communication contract, which is a standard recognized by the platform and plug-ins (Interface(ImplementThe interface type object can be recognized by the plug-in engine as a plug-in component;

LFramework plug-in. The plug-in type is stored in the plug-in assembly and can be used by plug-in engine parsing and host programs. It is the bearer of the specific functions of the plug-in framework.

LThe additional component library is not a necessary part of the plug-in framework. It is a variety of tool sets and class libraries developed to help the framework better run, such as the Query Class through packaging, symbolic class;

Figure2 limit 1General Structure Diagram of the plug-in framework:

In this chapter, we will first learn about ArcMap software plug-in mechanisms. Although ArcMap Yes com mechanisms to implement plug-in frameworks, but this process can give developers enough inspiration. Then we will introduce the plug-in GIS plug-in engine design, implementation methods, and usage in the application framework . net framework2.0 advanced knowledge, such as attributes, inheritance, interfaces, reflection, and collections.

we will first introduce various related knowledge points, but they are not the entry-level content. This book assumes that the reader is familiar with related concepts and lacks the skills to apply these concepts. Based on an in-depth explanation of these knowledge points, each chapter provides a detailed application framework implementation Code .