API Evangelist enhancements for SS&C Eze EMS xAPI

overlay: 1.0.0
info:
  title: API Evangelist enhancements for SS&C Eze EMS xAPI
  version: 1.0.0
x-provenance:
  generated: '2026-09-13'
  method: generated
  source: openapi/ss-c-technologies-eze-ems-xapi-openapi.json
  extends: openapi/ss-c-technologies-eze-ems-xapi-openapi.json
  note: >-
    This overlay carries API Evangelist's additions only. It never mutates the original document,
    which stays verbatim as fetched from https://emsuatxapi.taltrade.com:9001/swagger/v1/swagger.json
    on 2026-09-13. Every action below adds metadata the published spec omits — a server block, a
    contact, tag descriptions, and per-operation consequence markers on the writes. No operation's
    parameters, schemas or responses are altered.
actions:
- target: $.info
  description: >-
    Name the publisher and point at the contract's real home. The published info block carries only
    title and version.
  update:
    description: >-
      Cross-platform execution-management API for Eze EMS. The gRPC contract at
      https://github.com/ezesoft/xapi/tree/master/protos is the source of truth; this document is
      its REST projection. Connect returns a UserToken that must be supplied on every subsequent
      call. A 200 does not by itself indicate success — read ServerResponse and ServerAcknowledgement.
    contact:
      name: SS&C Eze
      url: https://github.com/ezesoft/xapi
    x-published-by: SS&C Technologies (SS&C Eze)
    x-source-of-truth: grpc/ss-c-technologies-xapi-order.proto, grpc/ss-c-technologies-xapi-market-data.proto, grpc/ss-c-technologies-xapi-utilities.proto
- target: $
  description: >-
    The published document declares no servers[] block at all, so a generated client has no host.
    Add the UAT host SS&C Eze names in its own readme, marked as UAT; production host and port are
    provisioned per client.
  update:
    servers:
    - url: https://emsuatxapi.taltrade.com:9001
      description: >-
        UAT. The only host SS&C Eze publishes for the REST surface, named in the integration-resources
        line of https://github.com/ezesoft/xapi/blob/master/readme.md. Production server and port are
        supplied by an SS&C Eze client service representative.
- target: $.tags
  description: Tag descriptions. The published document declares tags on operations but defines none.
  update:
  - name: SubmitOrderService
    description: >-
      Order lifecycle — single, pair, basket, allocation, book-trade and trade-report submission,
      amendment, cancellation, and order/execution detail retrieval. Projection of the
      SubmitOrderService gRPC service (17 RPCs).
  - name: MarketDataService
    description: >-
      Quotes, tick data, bars, option chains and greeks, symbol reference data and
      alternate-symbology resolution across ISIN, SEDOL, RIC, CUSIP and Bloomberg identifiers.
      Projection of the MarketDataService gRPC service (24 RPCs).
  - name: UtilityServices
    description: >-
      Session management (connect, disconnect, SRP login, MFA, password change), today's balances,
      net and broken-down positions and activity, strategies, routes and heartbeat. Projection of
      the UtilityServices gRPC service (23 RPCs).
  - name: UserServices
    description: User entitlement lookup.
  - name: XAPIServer
    description: Server liveness and readiness probes. The only operations that require no session.
- target: $.paths['/api/v1/order'].post
  description: Mark the highest-consequence write in the contract.
  update:
    x-consequence: irreversible-money-movement
    x-reversal: DELETE /api/v1/order (CancelSingleOrder), effective only while the order is working
    x-reversal-window: not published
    x-idempotency: none
- target: $.paths['/api/v2/order'].post
  description: Same marker on the v2 successor.
  update:
    x-consequence: irreversible-money-movement
    x-reversal: DELETE /api/v1/order (CancelSingleOrder), effective only while the order is working
    x-reversal-window: not published
    x-idempotency: none
- target: $.paths['/api/v1/orders'].post
  description: Basket submission fans out into individually cancellable orders.
  update:
    x-consequence: irreversible-money-movement
    x-reversal: cancel each resulting order individually via DELETE /api/v1/order
    x-idempotency: none
- target: $.paths['/api/v1/order/book-trade'].post
  description: No reversal operation exists for a booked trade.
  update:
    x-consequence: irreversible-money-movement
    x-reversal: none published
    x-idempotency: none
- target: $.paths['/api/v1/order/trade-report'].post
  description: No reversal operation exists for a trade report.
  update:
    x-consequence: irreversible-money-movement
    x-reversal: none published
    x-idempotency: none
- target: $.paths['/api/v1/order/allocation-order'].post
  description: No reversal operation exists for an allocation.
  update:
    x-consequence: irreversible-money-movement
    x-reversal: none published
    x-idempotency: none
- target: $.paths['/api/v1/authentication/connect'].get
  description: >-
    Flag the credential-in-query-string shape and the published lockout, both of which a client
    must design around and neither of which the spec states.
  update:
    x-credentials-in-query: true
    x-rate-limit: 3 login attempts per 60 seconds locks the account for 3 minutes, successful attempts included
    x-rate-limit-source: https://github.com/ezesoft/xapi/blob/master/faq.md
    x-returns: UserToken, required on every subsequent call
- target: $.paths['/api/v1/authentication/change-password'].get
  description: Same credential-transport note.
  update:
    x-credentials-in-query: true
- target: $.components.schemas['Google.Rpc.Status']
  description: >-
    Name the standard this envelope comes from so a generated client can map code to a known
    enumeration instead of treating it as an opaque integer.
  update:
    description: >-
      The gRPC canonical error model (google.rpc.Status). `code` is a google.rpc.Code value
      (0 OK … 16 UNAUTHENTICATED). `details` carries google.protobuf.Any payloads whose concrete
      types are not declared in this document. This is the only error shape in the API; no 4xx or
      5xx status code is declared on any operation.
    x-standard: google.rpc.Status