Preparing document preview In Composition Center, the business user designs the document definitions and previews examples of the final documents. You must do some preparations to make the preview possible. For example, enable the Message to be invoked through web service requests and provide sample files to simulate input data. Configuration steps 1 Enable the Message to be invoked through service requests. See Service-enabling the Message. 2 Create preview output connectors manually (optional). See Creating an output connector for document preview (optional). 3 Add the sample files used to simulate input data. See Adding a sample file.