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The "Tapestry5HowToCreateADispatcher2" page has been changed by BasileChandesris. http://wiki.apache.org/tapestry/Tapestry5HowToCreateADispatcher2?action=diff&rev1=4&rev2=5 -------------------------------------------------- In the article [[Tapestry5HowToCreateADispatcher]] we covered the basics of creating a Dispatcher and getting it into the pipeline. This quick article is a supplement to that one, continuing the example of implementing an access control mechanism. Specifically, we will cover how to access request-specific state objects (ASOs) from a singleton service (our access controller). If you haven't already read that article, you should do so before proceeding. - Before reading this be sure to first read about how Tapestry manages application state: + Before reading this be sure to first read about how Tapestry5 manages application state: - http://tapestry.apache.org/tapestry5/tapestry-core/guide/appstate.html + http://tapestry.apache.org/tapestry5/guide/appstate.html This is a fairly quick and painless read and should get you up to speed on what application state is, when and why you need it, how to use it, and the basics of how it works. The following javadocs are also worth pointing out: - [[http://tapestry.apache.org/tapestry5/apidocs/org/apache/tapestry/annotations/ApplicationState.html|ApplicationState]], [[http://tapestry.apache.org/tapestry5/apidocs/org/apache/tapestry/services/ApplicationStateManager.html|ApplicationStateManager]] + [[http://tapestry.apache.org/tapestry5/apidocs/org/apache/tapestry5/annotations/ApplicationState.html|ApplicationState]], [[http://tapestry.apache.org/tapestry5/apidocs/org/apache/tapestry5/services/ApplicationStateManager.html|ApplicationStateManager]] == A Glance at the Problem == The access controller we've implemented is a singleton service. It doesn't make sense to implement it per-request as the only per-request state it needs are the access permissions of the requesting user. However we can't just annotate a service field with @!ApplicationState as we normally would in a page or component. This annotation ties a field to a request, but singleton services have no such association to any request. They are instantiated once and accessible by all concurrent requests, at the same time. @@ -28, +28 @@ == A Solution in Code == - Here is how we could implement the solution. Assume that we have a class named !UserPermissions for storing the permissions, and that it contains a method named canAccess. This method returns a boolean showing if the user can access the resource (page) represented by the [[http://tapestry.apache.org/tapestry5/apidocs/org/apache/tapestry/services/Request.html|Request]] object. + Here is how we could implement the solution. Assume that we have a class named !UserPermissions for storing the permissions, and that it contains a method named canAccess. This method returns a boolean showing if the user can access the resource (page) represented by the [[http://tapestry.apache.org/tapestry5/apidocs/org/apache/tapestry5/services/Request.html|Request]] object. {{{ import java.io.IOException; - import org.apache.tapestry.services.ApplicationStateManager; + import org.apache.tapestry5.services.ApplicationStateManager; - import org.apache.tapestry.services.Request; + import org.apache.tapestry5.services.Request; - import org.apache.tapestry.services.Response; + import org.apache.tapestry5.services.Response; public class AccessController implements Dispatcher { @@ -93, +93 @@ == Conclusion == - It has been noted on the mailing list that access control can be implemented using this same technique, but as a [[http://tapestry.apache.org/tapestry5/apidocs/org/apache/tapestry/services/RequestFilter.html|RequestFilter]] instead. I haven't tried this but the same concepts regarding ASOs apply. + It has been noted on the mailing list that access control can be implemented using this same technique, but as a [[http://tapestry.apache.org/tapestry5/apidocs/org/apache/tapestry5/services/RequestFilter.html|RequestFilter]] instead. I haven't tried this but the same concepts regarding ASOs apply. Any suggestions, corrections, or other furtherings on this document are most welcome. If you'd like to chat with me about this, you can find me in #tapestry on irc.freenode.net (chrislewis). --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
