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The following page has been changed by MichaelJouravlev: http://wiki.apache.org/struts/ComposableRequestProcessor ------------------------------------------------------------------------------ + For Struts 1.3, the RequestProcessor methods has been turned into Commands. Rather than subclassing a monolithic object, it is possible not just to replace Commands. It is also possible to insert or remove Commands, if needed, to extend or streamline the request processing gauntlet. + + The RequestProcessor class has been turned into ComposableRequestProcessor that invokes Command in the proper order. This order is defined with standard {{{chain-config.xml}}} file buried deep in Struts library, but can be easily overriden with custom config file if needed. To do this one need to define "chainConfig" property for !ActionServlet in {{{web.xml}}} file. This propertly should contain comma-separated list of either context-relative or classloader path(s) to load commons-chain catalog definitions from. If none specified, the default Struts catalog that is provided with Struts will be used. + + inline:struts_chain.gif + + === todo === + Beginning with Struts 1.3.0, the original RequestProcessor class has been extended in a way that substantially overhauls the way in which a Struts module processes an HTTP Request. Before this version of Struts, the RequestProcessor class implemented a variation of the Template pattern, in that it articulated a primary "process" method which called various protected methods in a reliable order. Users who wanted to alter the request processing lifecycle were advised to extend RequestProcessor and override one or more of those methods. This led to a very inflexible environment, where it was very difficult to synthesize a request processing chain from library code, because of the familiar problems with "single inheritance" in Java. With the introduction of the ComposableRequestProcessor class, every request is handed to a composable chain of commands, each of which can perform a small bit of the request processing. @@ -16, +24 @@ Other notes on the ComposableRequestProcessor are welcomed! ---- - Ted Husted made a pretty good case for a composable chain of processors on the mailing list. For now, just a pointer: http://marc.theaimsgroup.com/?l=struts-dev&m=105472470724762&w=2 + Ted Husted made a pretty good case for a composable chain of processors on the mailing list. http://marc.theaimsgroup.com/?l=struts-dev&m=105472470724762&w=2 + Other links: + + http://www.onjava.com/pub/a/onjava/2005/03/02/commonchains.html + + http://www.onjava.com/pub/a/onjava/2005/03/02/commonchains2.html + + http://www.infonoia.com/en/content.jsp?d=inf.05.06&pr=1 +
