Editing Seam (section)

=Standard Functionality=

==JBoss EL==
Seam provides an extension to the standard Unified Expression Language (EL) called JBoss EL.

==Logging==
The <code>org.jboss.seam.log.log</code> (s. [[Seam#org.jboss.seam.annotations.Logger|annotations]]) class has a specialised syntax e.g.

 '''log.info("creating component '#0' on #1", name(), date());'''
 '''log.info("#{'''<SEAM COMPONENT>'''.'''<attribute>'''}");'''

Methods:
* info()
* debug()
* error()

==Security==
The security functionality was extended during between version 2.0.2 to 2.1.0 (s. documentation).

===Authentication===
For less complex applications Seam offers a simple method:
* configure components.xml to call the simple authentication method
* write an authentication method (no parameter, return true if success, else false) (s. [[Seam#Identity|Seam class identity]])
* write a login form

==Pageflow==
There are two ways to define pageflow in Seam:
* Using JSF or Seam navigation rules - the stateless navigation model
* Using jPDL - the stateful navigation model through jBPM integration

You can use them together or independently or not at all. 

===Stateless Navigation Model===

The stateless model defines a mapping from a set of named, logical outcomes of an event directly to the resulting page of the view. The navigation rules are entirely oblivious to any state held by the application other than what page was the source of the event. This means that your action listener methods must sometimes make decisions about the page flow, since only they have access to the current state of the application.

You can specify JSF- or Seam navigation rule. 

* seam pageflow navigation rules in <WAR-File>/WEB-INF/pages.xml

 <pages>
   <page view-id="<NAME>" [action="#{<COMPONENT.<METHOD>}"]>
     [<action if="<CONDITION>" execute="#{<COMPONENT>.<METHOD>}"/>]
   </page>
 </pages>

or

* as JSF navigation rule in faces-config.xml.

 <navigation-rule>
   <from-view-id>/numberGuess.jsp</from-view-id>
     <navigation-case>
       <from-outcome>guess</from-outcome>
       <to-view-id>/numberGuess.jsp</to-view-id>
       <redirect/>
     </navigation-case>
     <navigation-case>
       <from-outcome>win</from-outcome>
       <to-view-id>/win.jsp</to-view-id>
       <redirect/>
    </navigation-case>
 </navigation-rule>

* If you find navigation rules overly verbose, you can return view ids directly from your action listener methods, e.g.:

 public String guess() 
 {
   if (guess==randomNumber) return "/win.jsp";
   if (++guessCount==maxGuesses) return "/searchResults.jsp?searchPattern=#{searchAction.searchPattern}";
   return null;
 }

====<page>====
 <page view-id=<View> [action=<EL_Expression>] 
   <param name="<PARAM_NAME>" [value="#{<OJECTMODEL_TARGET>}"/>
 </page>

The action is executed just before rendering the page. The page action method can return a JSF outcome. If the outcome is non-null, Seam will use the defined navigation rules to navigate to a view.
The parameters are evaluated before page rendering and used for links via &lt;s:link> to this page.

===Stateful Navigation Model===

The stateful model defines a set of transitions between a set of named, logical application states. In this model, it is possible to express the flow of any user interaction entirely in the [[BPM#JPDL|jPDL]] pageflow definition, and write action listener methods that are completely unaware of the flow of the interaction.