google appengine中java后端的示例代码

Question

When i read doc of backend its tells how to configure ,etc.What what the code of a backend looks like?Is it just a servlet with extra entries in backend.xml file?

I tried to create a servlet with class com.xyz.Mybackend and servlet name Mybackend.

public Mybackend  extends HttpServlet{

 public void doGet(HttpServletRequest req, HttpServletResponse resp){

   while(true){
     //do something
     try{
      Thread.sleep(xyz);
     }catch(Exception ex){

     }
   }

}

Then i added following lines in backend.xml

<backends>
    <backend name="Mybackend">
    <class>B1</class>
    <options>
    <dynamic>true</dynamic>
    </options>
    </backend>
</backends>

Is that correct/enough?If yes.How to i start my backend now?It it by calling the backend servlet url?

http://localhost/mybackenurl ?

Answer 1

1. Yes, backends are just servlets.

2. You have to start backends manually via appcfg script: https://developers.google.com/appengine/docs/java/backends/overview#Backend_States

Answer 2

I know what you mean. I would have found the whole backends overview section a lot clearer the first time I read it if right at the top it said, backends are just special instances of servlets.

A popular way of starting a backends noone here has mentioned is by using push queues, as documented here, https://developers.google.com/appengine/docs/java/taskqueue/overview-push#Java_Push_queues_and_backends