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.

Overview and Engine diagnostics both let you stage the same runtime overrides. Overview is scoped to the session you are viewing; Diagnostics adds a cross-tenant session list and health readouts, and its Settings tab writes to the same runtime overrides shown here.

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.

Session Admin

Open Admin under a session in the sidebar to reach identity, restart, deletion, and the FIX session-layer messages. The page requires the simulator-operator role; in this deployment that resolves to platform administrators only (no FixPortal sign-in currently carries the scope the operator role checks for). Other users do not see the link, and a direct link redirects them to the session's Overview.

Edit identity changes a session's BeginString or CompIDs. Renaming disconnects the client and resets the order book; its HMAC secret and Sim Config are retained. Restart session reconnects the simulated acceptor and offers preserve simulation state to keep sequence numbers and the order book instead of resetting them. Delete session removes the session, its messages, and its order book, and cannot be undone.

Restart and deletion are administrative operations; capture the relevant session ID, UTC window, and traffic before using either.

Session messages

Session Admin's Session messages section sends FIX session-layer messages directly, outside the normal simulation flow:

• Send Heartbeat sends a Heartbeat (35=0) immediately.
• Send TestRequest sends a TestRequest (35=1) with a TestReqID you supply, or an auto-generated one if left blank.
• Prepare ResendRequest stages a ResendRequest (35=2) with the BeginSeqNo and EndSeqNo you set (0 means end of stream). Tick Acknowledge ResendRequest impact, then select Send ResendRequest.

Each of these acts on the session's live FIX connection, so the controls are disabled until the session is logged on.

Updated 2026-09-25 · Edit on GitHub