How to get String size in WSO2 ESB?

You can get the String size using Xpath expression. Find the blow steps:

1. Assign the string value to the property.
2. Get the value using Xpath expression.

 fn:string-length(get-property('StringValue'))

Find the below sample proxy.

<?xml version="1.0" encoding="UTF-8"?>
<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="Proxy1"
       startOnLoad="true"
       statistics="disable"
       trace="disable"
       transports="https,http">
   <target>
      <inSequence>
         <property name="stringvalue" value="Colombo"/>
         <property expression="fn:string-length(get-property('stringvalue'))" name="string_length"/>
         <log level="custom">
            <property expression="get-property('string_length')" name="Length"/>
         </log>
      </inSequence>
   </target>
   <description/>
</proxy>

 After executing this proxy, you can see the length value in console:

[2017-05-09 00:08:10,153]  INFO - LogMediator Lenght = 7.0