[seam-dev] Replacing pages.xml

[Gavin King]

You're probably right that a class is the right thing to use to
represent a page.

But I was actually wondering whether you can use an enumeration to
represent the pages of the app:

   public enum MyAppPage implements Page<MyAppPage> {
      @View(.....) login,
      @View(.....) main,
      @View(.....) logout;

      public MyAppPage next(MyAppPage page, Object outcome) {
         switch (page) {
            case login:
               if (Boolean.TRUE.equals(outcome))
                  return main;
               else
                  return login;
            case logout:
               return login;
            case main:
               return main;
            default:
               return page;
         }
      }
   }

where we define the following interface:

   public interface Page<X> {
	X next(X page, Object outcome);
   }

I don't see too much that is immediately wrong with this, but I have
not thought it through properly yet...

On Thu, Feb 18, 2010 at 10:58 PM, Stuart Douglas
<stuart at baileyroberts.com.au> wrote:
>
>
> I have been thinking about the replacement for pages.xml. Even though JSF2 has made some aspects of pages.xml redundant, pages.xml is still important as it allows you to apply actions/security setting etc to a large number of pages at once using wildcards. With that said however it would be nice to move to a design that is more typesafe and extensible. I have come up with a preliminary idea of how this might work, I will explain with an example:
>
> @PageMetadata
> public @Interface SecurityConfig
> {
>   boolean loginRequired();
>   String restrict();
> }
>
> /**
>  * This bean will only be considered for injection when the context path is
>  * /app/restricted/*, and it is the most specific page available.
>  */
> @ViewId("/app/restricted/*")
> @SecurityConfig(loginRequired=true)
> public class RestrictedArea extends Page
> {
>
> }
>
> This may also be configured via XML using seam-xml.
> There is nothing special about the page class, it is an empty class
> that is provided solely to be configured with annotations:
>
> <Page>
>  <ViewId>/app/restricted/*</ViewId>
>  <SecurityConfig loginRequired="true" />
> </Page>
>
> The application can get access to this information in a number of ways:
>
> @Inject PageDataProvider<SecurityConfig> data;
>
> public void doStuff()
> {
>  //get the most specific result
>  SecurityConfig security = data.get();
>
>  //get all applicable results
>  List<SecurityConfig> secinfo = data.getAll();
>
>  //secinfo is ordered from most to least specific,
>  //secinfo.get(0) will be equal to data.get()
>
> }
>
> Alternatively the most specific result can be injected directly:
>
> @Inject SecurityConfig data;
>
> We could also support an event based approach:
>
> public void pageEvent(@Observes @Rendered("/secure/*") Page page, SecurityConfig config)
> {
>  //do stuff
> }
>
> Does this sound like a good approach? I am fairly sure all this can be implemented as a portable extension.
>
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>



-- 
Gavin King
gavin.king at gmail.com
http://in.relation.to/Bloggers/Gavin
http://hibernate.org
http://seamframework.org