An Integration Procedure is designed to orchestrate multiple steps, including data retrieval, manipulation, and callouts. When a JSON response from an HTTP action needs to be converted to XML, the standard, declarative tool for this task is a DataRaptor Transform. DataRaptors are a core component of OmniStudio for data manipulation. A DataRaptor Transform is specifically designed to change the structure of data, and it explicitly supports converting a JSON input into a specified XML output format. This "clicks-not-code" approach is the most efficient and maintainable solution within the OmniStudio framework for this requirement.

A. Use a Remote Action that calls the XMLStreamReader class

XMLStreamReader is an Apex class used for parsing (reading) an existing XML document, not for generating (writing) one from a JSON source.

B. Use a Remote Action that calls the XMLStreamWriter class

While technically feasible to write custom Apex code using XMLStreamWriter, this is a programmatic solution. The platform provides a declarative tool (DataRaptor Transform) for this exact purpose, which is the preferred method.

D. Use a DataRaptor Extract and check the XML checkbox on the Output JSON Path.

A DataRaptor Extract is used to retrieve data from Salesforce objects. It is not designed to transform an existing in-memory JSON structure from a previous step (like an HTTP Action) into XML.

1. Salesforce Help

OmniStudio Documentation

"DataRaptor Transform Action": "Use a DataRaptor Transform Action to transform data. For example

you can transform the data structure of the output of a DataRaptor Extract Action or a REST API call to the required input format of a subsequent action." This confirms a DataRaptor Transform is the correct tool to use after an API call.

2. Salesforce Help

OmniStudio Documentation

"Transform JSON Input to XML Output": "A DataRaptor Transform can convert JSON input to XML output. In the Output tab

you select XML as the Output Type. You then map data from the input JSON to the output XML." This section explicitly details the exact functionality required by the question.

3. Trailhead

OmniStudio DataRaptors

"Transform Data with DataRaptors": This module explains the function of each DataRaptor type. The "DataRaptor Transform" unit states its purpose is to "convert data from one format to another

" including JSON-to-JSON

XML-to-JSON

and JSON-to-XML transformations.