This topic introduces Custom Message Responders: Message Responders that are created to send responses with a payload in a custom message format that Virtualize has been extended to support.
A Custom Message Responder allows you to define and send responses with a payload leveraging a custom message format—for example, mainframe message formats, binary formats, or any other kind of proprietary custom message format. These custom message formats are added to Virtualize via custom message formats via the Parasoft Extension Framework; for details on how to define these extensions, see About Parasoft's Extension Framework.
You can model your response payload as an XML document; the responder then automatically converts the XML to the native format before sending the message. If the responder receives a native format message, the responder can convert the message to XML so that you can attach tools such as the XML Data Bank to the incoming request.
When you go to add responders, you will see an option to add a responder named [Your Format] Message Responder. For instance, if your team extended Virtualize to support the FIX message format, you would see the following: 
You can now configure the Custom Message Responder as you would configure any other Message Responder. For details on configuring standard Message Responder behavior (e.g., correlations, performance profiles, etc.), see Message Responder Overview. There are only two differences to note:
- You can select any pre-defined message types for this format from the Message Type list.
You can customize any pre-defined GUI options for this format under the Conversion Options tab.
