What is load on startup element in web.xml file

specify the order in which we want to initialize various Servlets. Like first initialize Servlet1 then Servlet2 and so on.
This is accomplished by specifying a numeric value for the  <load-on-startup> tag. <load-on-startup> tag specifies that the servlet should be loaded
automatically when the web application is started.

The value is a single positive integer, which specifies the loading order. Servlets with lower values are loaded before servlets with
higher values (ie: a servlet with a load-on-startup value of 1 or 5 is loaded before a servlet with a value of 10 or 20). When loaded, the init() method of the servlet is called. Therefore this tag provides a good way to do the following:

start any daemon threads, such as a server listening on a TCP/IP port, or a background maintenance thread perform initialisation of the application, such as parsing a settings file which provides data to other servlets/JSPs If no <load-on-startup> value is specified, the servlet will be loaded when the container decides it needs to be loaded – typically on it’s first access. This is suitable for servlets that don’t need to perform special initialisation.

I hope that clears all the doubts regarding <load-on-startup> in web.xml.



About Krishna Srinivasan

He is Founder and Chief Editor of JavaBeat. He has more than 8+ years of experience on developing Web applications. He writes about Spring, DOJO, JSF, Hibernate and many other emerging technologies in this blog.