Applies a transport-specific format to the content of a SockJS frame resulting in a content that can be written out. Primarily for use in HTTP server-side transports that push data.

Formatting may vary from simply appending a new line character for XHR polling and streaming transports, to a jsonp-style callback function, surrounding script tags, and more.

For the various SockJS frame formats in use, see implementations of AbstractHttpSendingTransportHandler.getFrameFormat