I want to create report with .dat extension (DailyReport.dat) but I didn't found anything about it. Can anyone please share the details how to create .DAT report using jasper server.
I answered this through your sales rep.
The Text exporter in JasperReports does this.
Attached is a JRXML modified from the sample referred to in the documentation above and sample text output.
The key to designing reports for text output is to specify the visual elements in the report in terms of character width and height for the font you use.