Netscape Enterprise Server / iPlanet Web Server 4.0 and 4.1 supported the Java Servlet 2.1 specification. This specification did not include web applications. A deployment scheme was developed to make servlet deployment simpler. With the advent of Java Web Applications (.war files) and their deployment descriptors, it is no longer necessary to maintain a proprietary deployment system.
iPlanet Web Server 6.0 supported both types of deployment schemes, but the 4.x implementation referred to as legacy servlets was marked as deprecated. See Chapter 8: “Legacy Servlet and JSP Configuration” of the iPlanet Web Server, Enterprise Edition Programmer's Guide to Servlets.
Sun Java System Web Server 6.1 does not support Legacy Servlets. The legacy-style properties files for the server you want to migrate - servlet.properties, context.properties, and rules.properties - are removed during migration.
Because there is no one-to-one mapping for all of the features, legacy servlets cannot be migrated automatically.
For documentation and samples to help you migrate your 4.1 legacy-style servlets to the web applications structure, see the Sun Java System Web Server 6.1 SP10 Programmer’s Guide to Web Applications.