title: java, tomcat: what is the meaning of the id attribute in the tag web-app in web.xml?
body: <p>What is the meaning of web.xml <strong>id</strong> attribute of the <strong>web-app</strong> tag?</p>
  
  <p>Eclipse generated it as <strong>id="WebApp_ID"</strong>. I was using version the Servlet specification version 2.5, I switched to using 3.0, with the suggestion of <a href="https://stackoverflow.com/questions/2095024/servlet-3-issues-with-webfilter-and-webservlet-deployment/3386526#answers">this answer</a> that doesn't include that id.</p>
  
  <p>Is it really necessary? What is the value supposed to be?</p>