Comments below: | -----Original Message----- | From: Reynir H�bner [mailto:[EMAIL PROTECTED]] | Sent: Thursday, January 16, 2003 2:04 PM | To: Tomcat Users List | Subject: RE: Servlet channing | | I can of course only answer this for my self, but the main reason is | Struts is an implementation of a specific pattern. When I started writing | J2EE applications some time ago, struts was not fully grown. I had a | pattern in my mind that I wanted to have an implementation of. The main | thing in this pattern is the servlet chaining mechanism (btw, filters had | not be introduced (to tomcat or other app servers) when I wrote this | chaining mechanism).
I'm a big user of Struts and can't say enough about it :-) | I have to admitt the fact that I have never used struts, and I have not | really spent a lot of time on checking it out. | The functionality I wanted in my servlet-chains is the ability to create | streamlines, that have can have multiple starting nodes and an multiple | stop nodes. This means I need to be able to build in some "flow logic" | into the servlet chain mechanism, I can't see how that would be done with | filters, at least not in the way I want. Well, Struts acts like a controller to receive requests, then pull data in from your model (DB, XML, etc), attach it to the request as an attribute, then pass the request on to another resource to handle the display. Filters are great because you can lay them sort of before your ActionController receives the request. The reason that I say sort of, is that Filters act like PullParsers where once your Filter receives the request, YOU call the next item in the chain by passing the request and response up the chain. Here's how I'm using filters with Struts: I'm using the SecurityFilter to block access to resources on the server based on user roles. Then I have a CachingFilter bound to many resources to cache the output of a Struts Action so I can reduce processing and catch the request before it re-executes the Struts Action. Then I also have TransformationFilters setup so I can convert the response from an Action into PDF or HTML based on XML outputted by the succeeding JSP from the Action. | So I think servlet chaining, struts and filters all describe sepperate | patterns even though there isn't much difference between them. Correct, Filters do not replace Struts, but act like an added bonus at the view level of the MVC framework that Struts provides. | Each servlet in a chain has some specific purpouse such as determine the | user who is logged on, determine some data that will be used in the | presentation layer below the chain. If anyone has seen Intershops Enfinity | Pipelines my application does similar things, in similar ways except less | propriatary. | | | -reynir Jacob Hookom -- To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]> For additional commands, e-mail: <mailto:[EMAIL PROTECTED]>
