Adding User-Defined Scripting Code to Mashups

Scripting Languages

You identify the scripting language in the type attribute using its MIME type. Currently EMML supports JavaScript and JRuby 1.0 as scripting languages within mashup scripts.

JavaScript support is included in EMML using Rhino. No changes are needed for your development or production environments. For more information on JavaScript support, see http://www.mozilla.org/rhino/.

For JRuby support, you must install and configure JRuby in your development and production environments. See Installing and Configuring JRuby for Mashups.

Import Script Libraries

You can include JavaScript or JRuby files from the local server using the src attribute.

For example:

<script type="text/javascript" src="myFunctions.js" 
  inputvariables="$order, $customer" 
  outputvariable="$scriptResult"/> 
... 
<script type="ruby" src="myRubyScript.rb" 
  inputvariables="$order, $customer" 
  outputvariable="$scriptResult"/>

The script has access to any variables that you pass in inputvariables. Order is not important. The result of the script, if any, is placed in outputvariable.

Include Scripts Directly

For JavaScript, you can also simply include scripting code directly in the body of <script>. This feature is not available for JRuby scripts.

You must enclose your JavaScript code in a CDATA section. This ensures that any characters in the JavaScript code that are delimiters in XML, such as <, are not misinterpreted. For example:

<script type="text/javascript" inputvariables="$reviewers" 
    outputvariable="$newPayload"> 
  <![CDATA[ 
    var newPayload = TopReviewers; 
    if ( reviewers.reviewer.rating > 3 )  { 
         newPayload.TopReviewers +=  <name>{i.name}</name>; 
       } 
  ]]> 
</script>

Access to Mashup Variables

Scripting code, whether JRuby or JavaScript, can only add to or update the mashup variable returned as the output variable of <script>.

JRuby scripts can only access those mashup variables that you pass to <script> using the inputvariables attribute. JavaScript code can access any mashup variable. However, this can impact performance. It is a best practice to pass mashup variables to JavaScript code using the inputvariables attribute in <script>.

You can pass any number of variables in inputvariables, separated by commas. For example:

<script type="text/javascript" inputvariables="$Orders"> 
<![CDATA[ 
  var myName = Orders.order.customer.firstname; 
  var orderID = Orders.order.@id; 
  var items = Orders..item \\contains all items in Orders 
  for each (i in items) { 
    totalprice += i.price * i.quantity; 
  } 
  Orders.order.item +=  <item><description>Catapult</description><price>139.95</price></item>; 
]]> 
</script> 
... 
<script type="ruby" src="myRubyScript.rb" 
  inputvariables="$feedData,$myDoc" outputvariable="$rubyResult"/>

Access to Java Classes

For JRuby scripts, access to Java classes is implicit in the language. See JRuby documentation for more information.

For JavaScript scripts, the following classes are accessible in a <script> command

Use fully-qualified class names, such as in this example:

<script type="text/javascript"> 
<![CDATA[ 
  var p = java.util.regex.Pattern.compile("a*b"); 
  var m = p.matcher("aaaaab"); 
  var b = m.matches(); 
  print(b); 
]]> 
</script>