A FIX acceptor: listens for initiators and runs a session for each.

Where FixAlchemy.Client dials a venue, a server waits to be dialed. It owns a listening socket, and every connection it accepts becomes a FixAlchemy.Server.Session that identifies itself by its Logon before it becomes a session at all.

Both sides run the same FixAlchemy.Engine, so an accepted session behaves the same as an initiated one once logon is complete: subscribers receive {:fix, type, raw, meta}, sequence recovery and validation work the same way, and sessions register in FixAlchemy.Registry under {connection_id, session_name}.

{:ok, _server} =
  FixAlchemy.Server.start_link(
    server_id: "acme",
    port: 5001,
    spec_file: "priv/specs/FIX44.xml",
    validate_inbound: true,
    sessions: [
      [
        connection_id: "acme_client",
        sender_comp_id: "ACME",
        target_comp_id: "CLIENT",
        handlers: [MyApp.OrderHandler]
      ]
    ]
  )

Options

• :server_id - names the server in the registry (required)
• :port - the port to listen on; 0 asks the operating system for one, readable afterwards with port/1 (required)
• :sessions - the sessions this server accepts, each carrying at least :sender_comp_id and :target_comp_id; see FixAlchemy.Server.Logon (required)
• :spec_file / :app_spec_file - the FIX dictionary, as FixAlchemy.Parser.init/1 takes them
• :tls - accept TLS rather than plain TCP; pass :certfile and :keyfile (or any other :ssl server option) in :tls_opts
• :ip - the interface to bind, default all
• :authenticate - a function replacing per-session credential checking
• :validate_inbound - check every inbound message and Reject a bad one, default false; an acceptor exposed to a counterparty it does not control should turn this on
• :sequence_recovery, :validate_checksum, :message_store, :routing_keys - passed to each session's FixAlchemy.Engine

Everything a matched session declares overrides the server-wide value, so one server can accept sessions with different handlers, roles, or storage.