HTTP output is the default for Universal Display Files. The output can be redirected to a file on the IFS if the "destination" property on the record format is set. Otherwise, HTTP output is assumed and the program must be run using the Web Connector.
A valid HTTP response includes at minimum a Content-Type header. The Universal Display File Handler will output the HTTP header at the time a record format is first written after file open. The "content type" property on the record format can be used to set this. If not specified, a content type will be determined based on the "document type" property. Other properties, such as "custom header" can be used to produce further header messages.
HTTP output is not buffered, so there is no possibility to change the HTTP header after the first record format is written.