org.onehippo.forge.hipshoot.spring.boot.support.servlet

Class DeferredInitDelegatingServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

org.onehippo.forge.hipshoot.spring.boot.support.servlet.DeferredInitDelegatingServlet

All Implemented Interfaces:

Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public class DeferredInitDelegatingServlet
extends javax.servlet.http.HttpServlet

Delegating Servlet that defers the initialization of the delegate servlet and delegates calls to the delegate servlet.

This delegating servlet with 'deferring initialization' feature can be useful if you want to start a web application fast enough without waiting for a servlet initialization to complete. For example, when you deploy spring boot based web application(s) onto a cloud based platform, you don't have to worry about the timeout issue (e.g, 60 seconds by default somewhere) due to a long time initializing servlet.

For example, suppose you have a servlet that may take long time to initialize itself like the following:

 <servlet>
   <servlet-name>LongTimeInitServlet</servlet-name>
   <servlet-class>org.example.LongTimeInitServlet</servlet-class>
   <load-on-startup>100</load-on-startup>
 </servlet>
 

You can change the servlet-class to org.onehippo.forge.hipshoot.spring.boot.support.servlet.DeferredInitDelegatingServlet and provide the real delegate servlet class name in the DeferredInitDelegatingServlet.delegateServletClass init parameter instead like the following example:

 <servlet>
   <servlet-name>LongTimeInitServlet</servlet-name>
   <servlet-class>org.onehippo.forge.hipshoot.spring.boot.support.servlet.DeferredInitDelegatingServlet</servlet-class>
   <init-param>
     <param-name>DeferredInitDelegatingServlet.delegateServletClass</param-name>
     <param-value>org.example.LongTimeInitServlet</param-value>
   </init-param>
   <load-on-startup>100</load-on-startup>
 </servlet>
 

Then this servlet class will pass the servlet initialization phase fast because the real initialization of the delegate servlet will be done asynchronously so that the servlet container may start all the other web applications faster without having to wait for the delegate servlet to complete the initialization phase.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
DeferredInitDelegatingServlet()

Method Summary

Modifier and Type	Method and Description
void	destroy()
void	init(javax.servlet.ServletConfig servletConfig)
void	service(javax.servlet.ServletRequest req, javax.servlet.ServletResponse res)

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doGet, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service

Methods inherited from class javax.servlet.GenericServlet

getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DeferredInitDelegatingServlet

public DeferredInitDelegatingServlet()

Method Detail

init

public void init(javax.servlet.ServletConfig servletConfig)
          throws javax.servlet.ServletException

Specified by:

init in interface javax.servlet.Servlet

Overrides:

init in class javax.servlet.GenericServlet

Throws:

javax.servlet.ServletException

destroy

public void destroy()

Specified by:

destroy in interface javax.servlet.Servlet

Overrides:

destroy in class javax.servlet.GenericServlet

service

public void service(javax.servlet.ServletRequest req,
                    javax.servlet.ServletResponse res)
             throws javax.servlet.ServletException,
                    IOException

Specified by:

service in interface javax.servlet.Servlet

Overrides:

service in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

IOException