What does a successful login message look like?
A valid login message follows standard FIX session-level fields.
A successful login message uses FIXT.1.1 and includes sender and target IDs, message sequence numbers, and session parameters. The format is:
8=FIXT.1.1|9=##|35=A|34=##|49=MPIDP##|52=YYYYMMDD-HH:MM:SS.FFF|56=OCEA|98=0|108=<0-90>|1137=9|1408=1.13|10=###|