When the logic of a mashup must change dynamically, you need to create a mashup script on the fly and execute it. You can use the built-in executeDynamicEMML macro to do this. This macro is installed with the Presto Server and is available for use in any mashup script.

The executeDynamicEMML macro allows you to generate a mashup script dynamically using the <script> statement and JavaScript or using Java classes. See <script> for more information on using JavaScript. See Using Java Classes in a <script> Statement for information on using Java classes in a mashup.