The drag and drop part should be easy once the parser is done.
I think there needs to be a much more detailed definition of the records you posted to be able to parse them.
In the record shown below, I see the following special characters: :, ->, =, |, ]
Plus I see what are probably key words: INFO, FIX, STP_CLIENT, DEBUG, QF
|INFO|FIX.4.2:STP_SERVER->STP_CLIENT: 8=FIX.4.29=7635=034=112549=STP_SERVER52=20100817-22:17:00.92656=STP_CLIENT10=201
17-08-10 22:17:00.929|QFJ Timer|quickfixj.trace|DEBUG|FIX.4.2:STP_SERVER->STP_CLIENT: File store: set(1125)
I don't see the sub message (8=FIX.4.2 35=0) in the above.
Bottom line, no way with what you described to parse this.