Sessions
A session is one FIX acceptor identity owned by a tenant. It combines protocol identity, connection state, traffic, orders, runtime controls, and persisted simulation policy.
Supported protocols
Sessions use FIX 4.2, FIX 4.4, or FIXT.1.1 with FIX 5.0 SP2 application messages. The BeginString and CompIDs form the stable identity; changing them is an administrative operation, not an ordinary runtime adjustment.
Session Overview
Overview is the live control surface. It shows connection and activity and exposes live overrides for new-order, cancel, and replace acknowledgements, fill rate, and Reject Inbound. These changes are useful during a test and do not redefine the persisted baseline.
Use Clear live overrides to return overridden settings to Sim Config. Overrides are held by the simulator service, so refreshing the browser does not clear them. A service restart clears them, and a clean-slate session restart clears them with the other session state. If actual behaviour differs from saved configuration, check Overview first.
Traffic and orders
- Traffic provides log replay and, when enabled for the workspace, load testing.
- Blotter In focuses on messages received from your initiator.
- Blotter Out focuses on messages sent by the simulator.
- IOI Composer sends and cancels indications of interest for a logged-on session.
- Blotter In shows working and completed orders and only offers lifecycle actions valid for the current state. See Blotters and order actions.
- Routes shows pending routed work and recent route actions.
The UI receives live updates through SignalR, while REST remains the command and query boundary. If live counters stop moving, refresh the underlying data before assuming the FIX engine stopped.
Configuration boundaries
Use Sim Config for durable probability, timing, dictionary, custom-tag, identification, rules, and routing settings. Use Multi-broker routing for broker allocation and wire mode. Use Library for tenant dictionaries, brokers, and ATDL files.
Restart and deletion
Changing a session's BeginString or CompIDs renames it, disconnects the initiator, and resets the order book and sequence state. Its HMAC secret and Sim Config are retained. Restart and deletion are administrative operations; capture the relevant session ID, UTC window, and traffic before using either.
When diagnosing a scenario, capture the session ID, UTC time window, ClOrdID, and both blotter directions. Those four facts usually reduce the search to one message chain.
Updated 2026-09-08 · Edit on GitHub