Question

Is element <load-on-startup> optional for a <servlet> definition in the Java Web application deployment descriptor (WEB-INF/web.xml)?

Answer 1

Yes…

For example, http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd says

<xsd:element name="load-on-startup"
       type="j2ee:xsdIntegerType"
       minOccurs="0">
<xsd:annotation>
  <xsd:documentation>

    The load-on-startup element indicates that this
    servlet should be loaded (instantiated and have
    its init() called) on the startup of the web
    application. The optional contents of these
    element must be an integer indicating the order in
    which the servlet should be loaded. If the value
    is a negative integer, or the element is not
    present, the container is free to load the servlet
    whenever it chooses. If the value is a positive
    integer or 0, the container must load and
    initialize the servlet as the application is
    deployed. The container must guarantee that
    servlets marked with lower integers are loaded
    before servlets marked with higher integers. The
    container may choose the order of loading of
    servlets with the same load-on-start-up value.

  </xsd:documentation>
</xsd:annotation>
  </xsd:element>