⭐️⭐️⭐️Introduction

🚕🚕🚕EXP (Extension Plugin) Extension Point Plugin System

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Related Articles 🎯🎯🎯EXP: A Java Plugin Hot-Swapping Framework

Noun Definitions:

🏅 Main Application: EXP needs to run on a JVM, typically as a Spring Boot application, which is referred to as the main application.

🎖 Extension Point: An interface defined by the main application that can be implemented by plugins. It's important to note that plugins are concrete implementations of extension points, while extension points themselves are merely interface definitions. A plugin can contain implementations for multiple extension points, and a single extension point can have implementations from multiple plugins.

🥇 Plugin: Supports extending functionality through a plugin mechanism, similar to plugins in tools like IDEA or Eclipse. The code within a plugin follows a format similar to Spring (if your application operates within a Spring environment).

🥈 Hot Swapping: Plugins have the ability to be removed from the JVM and Spring container. They support dynamic installation of JAR and ZIP files at runtime. This means you can add, remove, or replace plugins while the application is running, enabling dynamic extension and upgrades of the system.

The above describe the terms and definitions related to the EXP (Extension Plugin) Extension Point Plugin System. This system allows you to build applications with dynamic extension capabilities, adding and managing new functional modules through the use of plugins in the main application.

🎧Example

Both Guizhou Maotai and Wuliangye have purchased your company's standard products. However, due to custom requirements from the clients, new features need to be developed.

• Guizhou Maotai has customized 2 plugins.
• Wuliangye has customized 3 plugins.
• During runtime, the program will perform logic switching based on the client's tenant ID.

Scenario:

• Large B2B customers customize their business processes, requiring extensions to the main codebase.

  • The conventional approach involves pulling branches from Git.
  • The current method employs an extension point-based approach for customization, allowing hot-swapping.

• Multiple programs need to be divisible and combinable, supporting the deployment of multiple Spring Boot applications as a single unit or separately.

• Extension points are similar to Swagger documentation, serving as documentation for the plugin system, which is showcased on the management platform.

Feature

1. Support hot-swapping or loading during startup (Spring or regular JVM).
2. Based on the classloader Parent First isolation mechanism.
3. Support multiple implementations for a single extension point in a multi-tenant scenario, with tenant-based filtering for business logic, and customizable sorting for multiple tenant implementations.
4. Compatible with Spring Boot 3.x/2.x/1.x dependencies.
5. Enable plugins to expose Spring Controller REST endpoints externally, with hot-swapping capability.
6. Allow plugins to override Spring main application Controllers.
7. Provide support for plugins to access exclusive configurations, enabling customizable design for hot-reloading plugin configurations.
8. Support transaction binding between plugins and the main application.
9. Offer a stream API to ensure a cleaner integration of extension points into the main application.

USE

Environment:

1. JDK 1.8
2. Maven

git clone git@github.com:stateIs0/exp.git
cd all-package
mvn clean package

Main Application Dependencies(springboot starter)

<dependency>
    <groupId>cn.think.in.java</groupId>
    <!-- Here is a Spring Boot 2 example. If it's a regular application or a Spring Boot 1/3 application, please replace the artifactId.  -->
    <artifactId>open-exp-adapter-springboot2-starter</artifactId>
</dependency>

Plugin Dependencies

<dependency>
   <groupId>cn.think.in.java</groupId>
   <artifactId>open-exp-plugin-depend</artifactId>
</dependency>

Using the Programming Interface API

ExpAppContext expAppContext = ExpAppContextSpiFactory.getFirst();

public String run(String tenantId) {
   List<UserService> userServices = expAppContext.get(UserService.class, TenantCallback.DEFAULT);
   // first The first is the tenant with the highest priority.
   Optional<UserService> optional = userServices.stream().findFirst();
   if (optional.isPresent()) {
       optional.get().createUserExt();
   } else {
       return "not found";
   }
}


public String install(String path, String tenantId) throws Throwable {
  Plugin plugin = expAppContext.load(new File(path));
  return plugin.getPluginId();
}

public String unInstall(String pluginId) throws Exception {
  log.info("plugin id {}", pluginId);
  expAppContext.unload(pluginId);
  return "ok";
}

Module

1. all-package Packaging module
2. bom-manager pom management, self-management and tripartite dependency management
   • exp-one-bom Self-package management
   • exp-third-bom Three-party package management
3. open-exp-code exp core
   • open-exp-classloader-container classloader isolation API
   • open-exp-classloader-container-impl classloader isolation API Implementation
   • open-exp-client-api core api module
   • open-exp-core-impl core api imple; inside shade cglib Dynamic Proxy, can not spring impl;
   • open-exp-document-api Extension point document api
   • open-exp-document-core-impl Extension point document export implementation
   • open-exp-object-field-extend Bytecode dynamic extension field module
   • open-exp-plugin-depend exp dependency
4. example exp Use sample code
   • example-extension-define Example extension point definition
   • example-plugin1 Sample plug-in implementation 1
   • example-plugin2 Sample plug-in implementation 2
   • example-springboot1 Examples springboot 1.x Examples
   • example-springboot2 Examples springboot 2.x Examples; use spring cglib Dynamic Proxy
5. spring-adapter springboot starter, exp Adaptive spring boot
   • open-exp-adapter-springboot2 springboot2 dependency
   • open-exp-adapter-springboot1-starter springboot1 dependency
   • https://github.com/stateIs0/open-exp-springboot3 springboot3 dependency

module dependency

core API

public interface ExpAppContext {
   /**
    * Gets all current plug-in ids
    */
   List<String> getAllPluginId();
   
   /**
    * Preload reads only the meta information and load boot class and configuration, and does not load beans.
    */
   Plugin preLoad(File file);
   
   /**
    * loading plugin
    */
   Plugin load(File file) throws Throwable;

   /**
    * Uninstall plugin
    */
   void unload(String pluginId) throws Exception;

   /**
    * Gets plug-in instances for multiple extension points
    */
   <P> List<P> get(String extCode);


   /**
    * To simplify the operation, code is the full path class name
    */
   <P> List<P> get(Class<P> pClass);


   /**
    * Gets a single plug-in instance.
    */
   <P> Optional<P> get(String extCode, String pluginId);
}

Streaming API

public interface StreamAppContext {

   /**
    * For apis with return values, you need to support streaming calls
    */
   <R, P> R streamList(Class<P> pClass, Ec<R, List<P>> ecs);

   /**
    * For apis with return values, you need to support streaming calls
    */
   <R, P> R stream(Class<P> clazz, String pluginId, Ec<R, P> ec);
}

extension

cn.think.in.java.open.exp.client.PluginFilter

/**
 * @Author cxs
 **/
public interface PluginFilterService {

   <P> List<P> get(String extCode, PluginFilter filter);

   <P> List<P> get(Class<P> pClass, PluginFilter callback);
}

Tenant filtering example code:

PluginFilter filter = new PluginFilter() {
   @Override
   public <T> List<FModel<T>> filter(List<FModel<T>> list) {
      return list;
   }
}
;
List<UserService> userServices = expAppContext.get(UserService.class, filter);
// first The first is the tenant's highest priority.
Optional<UserService> optional = userServices.stream().findFirst();

Here's an example code snippet demonstrating how a plugin can retrieve configuration:

public class Boot extends AbstractBoot {
    // 定义配置, key name 和 Default value;
   public static ConfigSupport configSupport = new ConfigSupport("bv2", null);
}
public String hello() {
   return configSupport.getProperty();
}

springboot config(-D or application.yml):

plugins_path={Plugin directory that exp actively loads when springboot starts}
plugins_work_dir={exp's working directory, which will extract the code into this directory, subdirectory named plugin id}
plugins_auto_delete_enable={Whether to automatically delete the existing plugin directory}
plugins_spring_url_replace_enable={Whether the plug-in can override the main program url, note that multi-tenant level override is not currently supported}
exp_object_field_config_json={The plug-in dynamically adds fields json, json 结构定义见: cn.think.in.java.open.exp.object.field.ext.ExtMetaBean}

License

Apache 2.0 License.

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