Dear Wiki user, You have subscribed to a wiki page or wiki category on "Struts Wiki" for change notification.
The following page has been changed by MichaelJouravlev: http://wiki.apache.org/struts/StrutsNavigationBasics The comment on the change is: Typos, style ------------------------------------------------------------------------------ - == Web Resources And Their Views == + == Web Resources, Actions And Views == + A typical web application is a collection of ''resources'' linked with each other. In Struts web resources are represented with one or more action classes. When a user requests a web resource to render itself, a corresponding action class selects an appropriate view and sends it to the browser. Contrary to page-oriented framewors like ASP.NET where a web resource equals to a web page, in Struts one web resource can have several corresponding web pages. - A typical web application is a collection of ''resources'' linked with each other. In Struts a web resource is represented with one or more pairs of an action class and a form bean. When a user requests a web resource to render itself, a corresponding action class selects an appropriate view and sends it to the browser. - - Struts approach differs from page-oriented framewors like ASP.NET. In ASP.NET a web resource equals to web page, while in Struts one web resource can have several corresponding web pages. inline:basic_action_asp.gif - Struts provides a clean separation between logical state of a web resource from its visual representation. Struts is agnostic to presentation technology, so a page can be displayed using JSP file, Tile definition, Velocity template, XSLT stylesheet or other rendering techniques. + Struts provides a clean separation between logical state of a web resource and its visual representation. Struts is agnostic to presentation technology; the output can be rendered using JSP file, Tile definition, Velocity template, XSLT stylesheet, PDF generator or other techniques. ==== Example ==== Consider the Action that performs a search. The author of this code should not bother neither about how exactly the search criteria is obtained, nor about how the search results are presented. His only job is to say "what happened" after the search took place. - There are three interesting outcomes: + There are three possible outcomes: * No results were found => outcome "none". * Exactly one result was found => outcome "single". * More than one result was found => outcome "multiple". - It is up to the application architect to decide to render the same resulting page for all outcomes or to render different page for every outcome. The code of the search action is not affected by this decision. + It is up to the application architect to decide how to visually represent the search result. He can choose to render one resulting page for all outcomes, or to render a different page for every outcome. The code of the search action is not affected by this decision. == Round Trip And Postback == @@ -32, +30 @@ The above interaction can be handled either with two different action classes or with one action class. - If two different action classes are involved, then the action class that renders a page is called ''render action'', while the class that processes submitted data is called ''submit action''. + If two different action classes are involved, then the action class that renders a page is called a ''render action'', while the class that processes submitted data is called a ''submit action''. - If only one action class handles both render and submit phases, then step 4 can also be referred to as a ''postback'', because input data is posted back to the same action that displayed the page. + If only one action class handles both render and submit phases, then step 4 can also be referred to as a ''postback'', because input data is posted back to the same action that has displayed the page. Steps 4 and 5 are collectively referred to as a ''round trip''. == Navigation Between Web Resources == - In a Struts application an action class selects an appropriate view, so a user cannot navigate to a specific view. What a user can navigate to is a specific action. Control can be transferred from action to action programmatically as well. + In a Struts application a user cannot navigate to a specific view, because viewsa are selected by actions. Instead, a user can navigate to a specific action. Control can be transferred from action to action programmatically as well. === Navigation Via Link === @@ -48, +46 @@ === Navigation Via Postback === - An action may render a page that contains an HTML form. When the form is submitted, the action can analyzed input data and either forward or redirect to another action. This way a user can be transferred to another web resource programmatically. + An action may render a page that contains an HTML form. When the form is submitted, the action analyzes input data and either forwards or redirects to another action. This way a user can be transferred to another web resource programmatically. - Struts allows submitting an HTML form to an arbitrary action, but to keep things under control it is recommended to process all submits in original web resource's action and then transfer control to destination action instead of directly submitting HTML form to destination action. + Struts allows submitting an HTML form to an arbitrary action, but it is recommended to process all submits in original web resource's action to keep things under control. The control should be transferred from the source action to destination action instead of directly submitting HTML form to destination action. === In-Server Forwarding === + Forwarding transfers the execution from the current action to the specified action on the same server. If original action has created a response stream, it is reused by the new action. After forwarding occurs and view is returned to the browser, the browser still shows the address of original action. This happens because the forwarding occurs on the server side and the browser remains unaware of it. - Forwarding transfers the execution from the current action to the specified action on the same server. If original action has created a response stream, it is reused by the new action. - - After forwarding occurs, the browser shows the address of original action because the forwarding occurs on the server side and the browser remains unaware of it. === Redirecting Via Browser ===
