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Understanding Order Management

Overview

The Order Server connects to the SOLA® order management system via the exchange’s licensed SAIL (SOLA® Access Information Language) protocol. The Order Server uses a standard TCP connection to the SAIL routing engine that is the interface to the SAIL trading engine server. These two servers together comprise the SOLA order management system.

Trade Number

In the SAIL protocol messages, LSE provides a unique 8-character, alphanumeric trade number that is used for order actions and identifies an instrument for a given trading day. The trade number is the unique identifier for each fill received by the gateway, and appears in the X_TRADER® Orders and Fills Window.

Order Server Data Flow

Note

Terminology used in the following data flow matches terminology used in the Gateway System - Logical Architecture diagram. Also, native orders are those orders normally accepted by the exchange's API.

The following is a description of the SAIL order connection from the Order Server on the LSE Gateway to the exchange’s trading engine.

  • Upon startup, the Order Server reads any working orders contained in the *_Mode_orders.tbl files into memory.
  • X_TRADER® submits an order to the Order Server.
  • After receipt, the Order Server passes it to the appropriate Order Router. For details on how the Order Server determines the Order Router to which it passes the order, refer to Order Router Selection.
  • The Order Router assigns a TT Order Number to the order and then updates the Order Book with the new order information. The TT Order Number is not sent to the exchange.
  • The Order Router records the order in its *_Mode_orders.tbl files.
  • The Order Router sends an ACCEPT/Add message to the trader’s Audit Trail (in X_TRADER®).
  • The Order Router sends the order to the LSE host.
  • Upon receipt, the exchange host sends an order confirmation (containing the exchange-provided Trade Number) back to the Order Router.
  • The Order Router updates the Order Book with the exchange’s Trade Numbers to indicate that a confirmation was received, and writes it to its *_Mode_orders.tbl files.
  • The Order Router sends the order confirmation (as an OK/ADD) to the trader’s Audit Trail in X_TRADER®.

Fill Server Data Flow

Note

Terminology used in the following data flow matches terminology used in the Gateway System - Logical Architecture diagram. Also, native orders are those orders normally accepted by the exchange's API.

The Logical Architecture diagram illustrates the following fill flow:

  • The LSE host matches the order.
  • The LSE host sends a fill with an assigned Trade Number (i.e., transaction number) to the Order Router.
  • The Order Router matches the fill to the recorded order in the Order Book and updates the Order Book according to the type of fill received:
    • If the Trade Number for the fill does not match a Trade Number for an order in the order book, the Order Router notifies the trader’s and supervisory trader’s Audit Trails that the trader received a fill but that the fill does not match any of the orders in the Order Book. The Order Router then attempts to generate a fill based upon the data received from the exchange.
    • If the fill completes the order, the Order Router removes the order from the Order Book.
    • If the fill does not complete the order (i.e., it is a partial fill), the Order Router updates the Order Book to reflect the partial fill.
  • The Order Router writes order changes to the *_Mode_orders.tbl files and records the fill in its unique fills.tbl file. If counterparty information is available, this is added to the fill record.
    Note

    The Order Server deletes completed orders from its *_Mode_orders.tbl files only when it restarts.

  • Simultaneously, the Order Router:
    • Sends a fill response to X_TRADER®. X_TRADER® displays a fill in the Audit Trail. X_TRADER® updates the relevant files and screens (i.e., if it is a complete fill, the order is removed from the X_TRADER® Order Book).
    • Sends the fill to the Fill Server.
  • X_TRADER® displays the fill in the Fill window.