- HTTP Invoker is a remoting technology provided by the Spring Framework that allows you to invoke remote services in a distributed system using HTTP as the communication protocol. It enables you to expose and access Java objects as remote services over HTTP, making it suitable for building distributed applications that involve Java-to-Java communication.
- Key features and concepts of HTTP Invoker:
Serialization:
- HTTP Invoker uses Java object serialization for data exchange between the client and server. This means that the objects passed between the client and server must be serializable.
Proxy-Based:
- Like other Spring remoting technologies, HTTP Invoker uses proxy-based mechanisms to make remote method calls look like local method calls. On the client side, you interact with a proxy object that handles the communication with the remote server.
URL Mapping:
- HTTP Invoker maps remote service URLs to specific service implementations on the server side. The URL usually corresponds to the service’s endpoint and is used to identify the service to invoke.
Security:
- You can integrate Spring Security for securing your HTTP Invoker services, ensuring that only authorized clients can access them..
Server Configuration:
Define the Service Interface:
- Create a Java interface that defines the methods you want to expose as remote services.
public interface MyService {
String sayHello(String name);
}
Implement the Service:
- Create a class that implements the service interface. This class will contain the actual implementation of the service methods.
public class MyServiceImpl
implements MyService
{
@Override
public String sayHello
(String name) {
return "Hello,
" + name + "!";
}
}
Configure Spring for HTTP Invoker:
- In your Spring configuration file (e.g., applicationContext.xml), configure the HTTP Invoker service exporter.
<bean name="/myService"
class="org.springframework
.remoting.httpinvoker
.HttpInvokerServiceExporter">
<property name="service"
ref="myService"/>
<property name="serviceInterface"
value
="com.example.MyService"/>
</bean>
- In this configuration:
- myServiceProxy is the proxy to the remote service.
- serviceUrl specifies the URL where the remote service is hosted.
- serviceInterface specifies the interface that defines the service contract.
Use the Proxy:
- Inject the proxy bean into your client code and use it to invoke remote service methods.
@Autowired
private MyService myServiceProxy;
public void invokeRemoteMethod() {
String result =
myServiceProxy.sayHello("Alice");
System.out.println(result);
}
- With this setup, you’ve configured an HTTP Invoker server to expose a remote service and a client to access it over HTTP. This allows you to call remote methods as if they were local, making it easier to build distributed Java applications.
