FIX Protocol Guides

How FIX works on a real session, with example messages you can open in the parser. For specific error messages, see FIX troubleshooting; for what changed between versions, see FIX version comparisons.

• FIX Order Lifecycle Explained

  How a FIX order moves from New Order Single to fill, cancel, replace or reject, with OrdStatus (39) and ExecType (150) at each step and example messages.

• FIX Session Layer Explained

  How the FIX session layer works: Logon, heartbeats and TestRequest, sequence numbers, ResendRequest, gap fill and Logout, with example messages.

• FIXT.1.1 and ApplVerID Explained

  How FIX 5.0 sessions use FIXT.1.1: BeginString, DefaultApplVerID (1137) on Logon, ApplVerID (1128) per message and the version codes, with examples.

• How to Read a FIX Execution Report

  Read a FIX Execution Report (35=8) field by field: ExecType, OrdStatus, quantities, prices and IDs, how to book fills safely and what differs in FIX 4.2.