INT-2491: Scripting: Variables Improvements

JIRA: https://jira.springsource.org/browse/INT-2491

* Add support variables for 'inline' scripts
* Add convenient attribute `variables` for script tags
* Introduce `BeanFactoryFallbackBinding` for groovy scripts.

INT-2491: Polishing

* Add check for duplication of provided variables
* Tests and Docs

Polishing

src/reference/docbook/groovy.xml

@@ -57,9 +57,26 @@
 
 	  Setting a custom GroovyObjectCustomizer is not mutually exclusive with <code>&lt;variable&gt;</code> sub-elements or
 	  the <code>script-variable-generator</code> attribute. It can also be provided when defining an inline script.
-	  For more information regarding <code>&lt;variable&gt;</code> and <code>script-variable-generator</code>, see the
-	  paragraph '<emphasis>Script variable bindings</emphasis>' of <xref linkend="scripting-config"/>.
-    </para>
+	  </para>
+	  <para>
+	  With <emphasis>Spring Integration 3.0</emphasis>, in addition to the <code>variable</code> sub-element,
+	  the <code>variables</code> attribute has been introduced. Also, groovy scripts have the ability to resolve a
+	  variable to a bean in the
+	  <interfacename>BeanFactory</interfacename>, if a binding variable was not provided with
+	  the name:
+	<programlisting language="xml">&lt;int-groovy:script&gt;
+	&lt;![CDATA[
+		entityManager.persist(payload)
+		payload
+	]]&gt;
+&lt;/int-groovy:script&gt;</programlisting>
+		  where variable <code>entityManager</code> is an appropriate bean in the application context.
+	  </para>
+	  <para>
+		For more information regarding <code>&lt;variable&gt;</code>, <code>variables</code>,
+		and <code>script-variable-generator</code>, see the
+		paragraph '<emphasis>Script variable bindings</emphasis>' of <xref linkend="scripting-config"/>.
+	  </para>
   </section>
 
   <section id="groovy-control-bus">

src/reference/docbook/scripting.xml

@@ -98,7 +98,32 @@
 </script:script>]]></programlisting>
 	As shown in the above example, you can bind a script variable either to a scalar value or a Spring bean reference. Note that
 	<code>payload</code> and <code>headers</code> will still be included as binding variables.
-
+  </para>
+  <para>
+	  With <emphasis>Spring Integration 3.0</emphasis>, in addition to the <code>variable</code> sub-element,
+	  the <code>variables</code> attribute has been introduced. This attribute and <code>variable</code> sub-elements
+	  aren't mutually exclusive and you can combine them within one <code>script</code> component. However variables must
+	  be unique, regardless of where they are defined. Also, since <emphasis>Spring Integration 3.0</emphasis>,
+	  variable bindings are allowed for inline scripts too:
+	  <programlisting language="xml">&lt;service-activator input-channel="input"&gt;
+	&lt;script:script lang="ruby" variables="foo=FOO, date-ref=dateBean"&gt;
+		&lt;script:variable name="bar" ref="barBean"/&gt;
+		&lt;script:variable name="baz" value="bar"/&gt;
+		&lt;![CDATA[
+   			payload.foo = foo
+   			payload.date = date
+   			payload.bar = bar
+   			payload.baz = baz
+  			payload
+		]]&gt;
+	&lt;/script:script&gt;
+&lt;/service-activator&gt;</programlisting>
+	  The example above shows a combination of an inline script, a <code>variable</code> sub-element and a <code>variables</code> attribute.
+	  The <code>variables</code> attribute is a comma-separated value, where each segment contains an '=' separated pair
+	  of the variable and its value. The variable name can be suffixed with <code>-ref</code>, as in the
+	  <code>date-ref</code> variable above. That means that the binding variable
+	  will have the name <code>date</code>, but the value will be a reference to the <code>dateBean</code> bean from the application context.
+	  This may be useful when using <emphasis>Property Placeholder Configuration</emphasis> or command line arguments.
   </para>
   <para>
     If you need more control over how variables are generated, you can implement your own Java class
@@ -115,7 +140,7 @@
     provide an implementation of <classname>ScriptVariableGenerator</classname> and reference it with the <code>script-variable-generator</code>
 	attribute:
    <programlisting language="xml"><![CDATA[<int-script:script location="foo/bar/MyScript.groovy"
-				script-variable-generator="variableGenerator"/>
+		script-variable-generator="variableGenerator"/>
 
 <bean id="variableGenerator" class="foo.bar.MyScriptVariableGenerator"/>]]></programlisting>
 	  If a <code>script-variable-generator</code> is not provided, script components use
@@ -124,7 +149,7 @@
 	  variables from the <code>Message</code> in its <code>generateScriptVariables(Message)</code> method.
 	  <important>
 	  You cannot provide both the <code>script-variable-generator</code> attribute and <code>&lt;variable&gt;</code> sub-element(s)
-	  as they are mutually exclusive. Also, custom variable bindings cannot be used with an inline script.
+	  as they are mutually exclusive.
 	  </important>
 	</para>
  </section>

src/reference/docbook/whats-new.xml

@@ -667,5 +667,13 @@
 				<xref linkend="file-reading"/>, <xref linkend="ftp-inbound"/>, and <xref linkend="sftp-inbound"/> for more information.
 			</para>
 		</section>
+		<section id="3.0-scripting-variables">
+			<title>Scripting Support: Variables Changes</title>
+			<para>
+				A new <code>variables</code> attribute has been introduced for scripting components.
+				In addition, variable bindings are now allowed for inline scripts.
+				See <xref linkend="groovy"/> and <xref linkend="scripting"/> for more information.
+			</para>
+		</section>
 	</section>
 </chapter>