Performance.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd">

<chapter id="performance">
  <title>Performance Tuning</title>
  
  <para>
    This chapter is an attempt to document in one place all the tips for getting the best performance from
    your Seam application.
  </para>
    
  <section>
    <title>Bypassing Interceptors</title>
    
    <para>
      For repetitive value bindings such as those found in a JSF dataTable or other iterative control 
      (like <literal>ui:repeat</literal>), the full interceptor stack will be invoked for every invocation of 
      the referenced Seam component.  The effect of this can result in a substantial performance hit, especially 
      if the component is accessed many times.  A significant performance gain can be achieved by disabling the 
      interceptor stack for the Seam component being invoked.  To disable interceptors for the component, add the 
      <literal>@BypassInterceptors</literal> annotation to the component class.       
    </para>
    
    <warning>
      <para>
        It is very important to be aware of the implications of disabling interceptors for a Seam component.
        Features such as bijection, annotated security restrictions, synchronization and others are 
        unavailable for a component marked with <literal>@BypassInterceptors</literal>.  While in most cases
        it is possible to compensate for the loss of these features (e.g. instead of injecting a component
        using <literal>@In</literal>, you can use <literal>Component.getInstance()</literal> instead) it is
        important to be aware of the consequences.
      </para>      
    </warning>
    
    <para>
      The following code listing demonstrates a Seam component with its interceptors disabled:
    </para>
    
    <programlisting role="JAVA"><![CDATA[@Name("foo")
@Scope(EVENT)
@BypassInterceptors
public class Foo
{
   public String getRowActions()
   {
     // Role-based security check performed inline instead of using @Restrict or other security annotation
     Identity.instance().checkRole("user");
     
     // Inline code to lookup component instead of using @In
     Bar bar = (Bar) Component.getInstance("bar");
   
     String actions;   
     // some code here that does something     
     return actions;
   }
}]]></programlisting>
    
    
    
  </section>
    
    
</chapter>