Analyze the working principle of OSGI Enroute Base Provider framework in the Java library
OSGI Enroute Base Provider is a framework for working in the Java library. It provides a simplified, modular and reused method to build and expand applications.This article will introduce its working principle and provide some Java code examples.
### 1. OSGI Enroute Base Provider framework
OSGI (open service gateway initiative) is a specification of a dynamic modular system, which defines a way to dynamically install, uninstall and manage modules during runtime.Enroute Base Provider is a framework built based on OSGI specifications, which provides a tool and library for building a modular application.
### 2. The main component of the framework
OSGI Enroute Base Provider framework mainly includes the following components:
#### 2.1 Provider
PROVIDER is the core component of the framework, which is used to provide services to other modules.It exposes the service by achieving specific interfaces and providing corresponding logic.Other modules can access these services by dependent injection or service discovery.
The following is the PROVIDER code of an example:
public interface GreetingProvider {
String getGreeting();
}
public class EnglishGreetingProvider implements GreetingProvider {
public String getGreeting() {
return "Hello!";
}
}
public class ChineseGreetingProvider implements GreetingProvider {
public String getGreeting() {
Return "Hello!";;
}
}
#### 2.2 Dependency Injection
Dependent injection is a design pattern that is used to decompose the dependencies between objects from the user, making the code more flexible and maintained.The OSGI Enroute Base Provider framework provides support for dependency injection, making the service call between modules easier.
The following is an example code that uses dependencies:
@Component // Statement as a component
public class GreetingService {
@Reference // Use dependency injection to get GreetingProvider
private GreetingProvider greetingProvider;
public void greet() {
String greeting = greetingProvider.getGreeting();
System.out.println(greeting);
}
}
#### 2.3 Service Discovery
Service discovery is a mechanism that is used to find and use services provided by other modules at runtime.OSGI Enroute Base Provider framework provides the function of service discovery, making the service call between the modules more convenient.
The following is a sample code discovered using a service:
public class GreetingClient {
public static void main(String[] args) {
ServiceReference<GreetingProvider> reference = ServiceFinder.find(GreetingProvider.class);
GreetingProvider greetingProvider = reference.get();
String greeting = greetingProvider.getGreeting();
System.out.println(greeting);
}
}
### 3. Framework work principle
The working principle of OSGI Enroute Base PROVIDER framework is as follows:
-D define the Provider interface and the corresponding implementation class.
-In the module, use the annotation to declare the Provider as a component, and use dependency injection to inject the provider into other components.
-In the service discovery mechanism, find the services provided by and use other modules during running.
Specifically, when users need a certain service, it can access the corresponding provider by dependent injection or service discovery.The framework will be responsible for analysis of dependency relationships and automatically inject the corresponding instance, or find and return the appropriate service instance according to the type of the service interface.
### in conclusion
OSGI Enroute Base Provider is a framework for working in the Java library. It provides a mechanism for dependent injection and service discovery to make it easier and more flexible to build and expand services in modular applications.Using this framework, developers can quickly build highly combined and scalable applications.
It is hoped that this article will help understand the working principle of OSGI Enroute Base Provider framework in the Java library.
