Hi all.. Is there any way to create data type (CDT) dynamically in the bac

You can create named CDTs (CDTs that show up on the Data Management page) by
1) Creating them with the Data Type designer in the designer interface
2) Importing an XSD
3) Deploying a custom plugin that defines a custom data type
4) Publishing a process model that calls a SOAP web service that defines CDTs on its WSDL

You can create ad-hoc data structures using dictionary syntax in expression rules, but these will only be accessible at run-time - you won't have access to them as named types on the Data Management page or in process models.

I just need the CDT structure to read xml file tag elements. I used a function torecord() to extract the contents but that needs CDT with elements corresponding to the tag elements in xml file. The issue I am facing is the xml file that I get is dynamic. So, I cannot have a static CDT created before hand. Could you please suggest if there is any other alternative to read the elements in XML file. Thanks in advance.

See if the xpath expressions will help with your use case:
forum.appian.com/.../Scripting_Functions.html