Custom JSP taglib lets you perform the global initialization right
in your JSP pages. Tag init is similar to the jsp:include but the
described page will be included (executed) only once. For example:
<%@ taglib uri="taglib.tld" prefix="global" %>
So you may include this fragment in all your JSP pages, but global.jsp will be executed only once for your application. Attribute scope lets you describe the level where this functionality will be provided: application or session. Also you can describe the executed code as a body for this tag.
Body tag lets you perform a global initialization. Parameters are:
1) page Describes a page that will be executed only one time within the given scope.
See also Coldtags suite - the largest collection of custom JSP tags.
Also in Coldtags: