Hi Vishal,
All interaction with Reltio is via REST. REST 'only' uses JSON. If you need an XML response, you are going to need to use an integration tool (MuleSoft can certainly do it, but any other one will be able to) to take the Reltio response and convert it to XML for you. For example, here is a link about how to do this in the Mulesoft community. If you are not using MuleSoft, just google 'convert XML to JSON' and the name of the tool that you are using.
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Gino Fortunato
Senior Solution Engineer
Reltio
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