Fix Connection Management Blueprint

Manages TCP connections for FIX protocol engines including server-side acceptors, client-side initiators, SSL/TLS encryption, automatic reconnection, and socket configuration

Feature	fix-connection-management
Category	Integration
Version	1.0.0
Tags	fix-protocol, tcp, acceptor, initiator, ssl, reconnection, financial-messaging
YAML Source	View on GitHub
JSON API	fix-connection-management.json

Actors

ID	Name	Type	Description
socket_acceptor	Socket Acceptor	system	Server-side component that binds to a port and accepts incoming TCP connections from trading counterparties
socket_initiator	Socket Initiator	system	Client-side component that establishes outbound TCP connections to remote FIX servers
ssl_layer	SSL/TLS Layer	system	Optional TLS termination layer wrapping plain socket connections for encrypted FIX messaging
application	Application Layer	system	Business application that receives connection lifecycle events

Fields

Name	Type	Required	Label	Description
connection_type	select	Yes	Connection Type
socket_accept_port	number	No	Socket Accept Port
socket_connect_host	text	No	Socket Connect Host
socket_connect_port	number	No	Socket Connect Port
socket_connect_source_host	text	No	Socket Connect Source Host
socket_connect_source_port	number	No	Socket Connect Source Port
reconnect_interval	number	No	Reconnect Interval
socket_nodelay	boolean	No	Socket Nodelay
socket_send_buffer_size	number	No	Socket Send Buffer Size
socket_receive_buffer_size	number	No	Socket Receive Buffer Size
socket_reuse_address	boolean	No	Socket Reuse Address
host_selection_policy	select	No	Host Selection Policy
ssl_certificate	text	No	Ssl Certificate
ssl_private_key	text	No	Ssl Private Key
ssl_ca_certificate	text	No	Ssl Ca Certificate

States

State field: connection_state

Values:

State	Initial	Terminal
stopped	Yes
pending
connected
disconnected

Transitions:

Name	From	To	Actor	Condition
	stopped	pending	socket_initiator
	stopped	connected	socket_acceptor
	pending	connected	socket_initiator
	pending	disconnected	socket_initiator
	connected	disconnected	system
	disconnected	pending	socket_initiator

Rules

• acceptor_binding: Acceptor binds to SocketAcceptPort and listens for incoming connections, Each accepted connection is mapped to a session based on SenderCompID/TargetCompID in the Logon message, SocketReuseAddress=Y allows the acceptor to restart without waiting for OS port release
• initiator_reconnection: On connection loss, initiator waits ReconnectInterval seconds before reattempting, Multiple target hosts can be configured (SocketConnectHost1, SocketConnectHost2, etc.) for failover, HostSelectionPolicy controls which host is tried first and how priority-based failover works
• ssl_security: SSL sessions use the same configuration as plain sessions but wrap the socket in TLS, Certificate and private key paths must be configured before starting, CA certificate path enables mutual TLS (mTLS) peer verification, SSL and non-SSL sessions cannot mix on the same port
• socket_tuning: TCP_NODELAY disables Nagle’s algorithm for sub-millisecond message delivery; recommended for low-latency trading, Buffer sizes should be tuned based on expected message throughput; larger buffers reduce system calls
• threading: Each connection runs I/O on a dedicated thread pool; session callbacks are invoked from I/O threads, Applications sharing state across sessions must synchronize access or use SynchronizedApplication wrapper

SLA

Scope	Max Duration	Escalation
reconnect_interval	30s
connection_timeout	10s

Outcomes

Port_bind_failed (Priority: 1) — Error: PORT_BIND_FAILED

Given:

• acceptor is starting
• configured SocketAcceptPort is already in use

Then:

• emit_event event: fix.connection.error

Result: Acceptor startup fails with ConfigError; application is notified

Ssl_handshake_failed (Priority: 2) — Error: SSL_HANDSHAKE_FAILED

Given:

• TCP connection established
• SSL/TLS is enabled
• certificate verification or cipher negotiation fails

Then:

• transition_state field: connection_state from: pending to: disconnected
• emit_event event: fix.connection.error

Result: Connection dropped; initiator will retry after reconnect interval

Connection_refused (Priority: 3) — Error: CONNECTION_REFUSED

Given:

• initiator is attempting to connect
• target host refuses the connection or is unreachable

Then:

• transition_state field: connection_state from: pending to: disconnected
• emit_event event: fix.connection.failed

Result: Connection attempt fails; initiator waits ReconnectInterval before retrying

Connection_lost (Priority: 4) — Error: CONNECTION_LOST

Given:

• session is in connected or logged_on state
• TCP socket receives error or zero-byte read (peer closed connection)

Then:

• transition_state field: connection_state from: connected to: disconnected
• emit_event event: fix.connection.lost

Result: Session is disconnected; initiator begins reconnect cycle

Connection_established (Priority: 9)

Given:

• initiator completes TCP handshake OR acceptor accepts incoming connection
• SSL handshake succeeds (if SSL is enabled)

Then:

• transition_state field: connection_state from: pending to: connected
• emit_event event: fix.connection.established

Result: TCP connection ready; FIX session logon can begin

Graceful_stop (Priority: 10)

Given:

• application calls stop() on acceptor or initiator

Then:

• emit_event event: fix.connection.stopped

Result: All sessions are logged out and sockets closed cleanly

Errors

Code	Status	Message	Retry
PORT_BIND_FAILED	500	Failed to bind to configured port	No
SSL_HANDSHAKE_FAILED	500	SSL/TLS handshake failed	No
CONNECTION_REFUSED	503	Connection refused by remote host	No
CONNECTION_LOST	503	Connection lost unexpectedly	No
CONFIG_ERROR	500	Connection configuration is invalid	No

Events

Event	Description	Payload
fix.connection.established	TCP connection (and optional TLS) successfully established	remote_host, remote_port, session_id, is_ssl
fix.connection.lost	Active connection dropped unexpectedly	session_id, remote_host, error_detail
fix.connection.failed	Outbound connection attempt failed	remote_host, remote_port, error_detail
fix.connection.stopped	Connection layer stopped cleanly	connection_type
fix.connection.error	Non-fatal connection-level error	remote_host, error_detail

Related Blueprints

Feature	Relationship	Reason
fix-session-management	required	FIX sessions are established on top of connections managed here
fix-message-persistence	recommended	Message store maintains sequences across connection drops and recoveries

AGI Readiness

Goals

Reliable Fix Connection Management

Manages TCP connections for FIX protocol engines including server-side acceptors, client-side initiators, SSL/TLS encryption, automatic reconnection, and socket configuration

Success Metrics:

Metric	Target	Measurement
success_rate	>= 99.5%	Successful operations divided by total attempts
error_recovery_rate	>= 95%	Errors that auto-recover without manual intervention

Constraints:

• availability (non-negotiable): Must degrade gracefully when dependencies are unavailable

Autonomy

Level: supervised

Escalation Triggers:

• error_rate > 5

Tradeoffs

Prefer	Over	Reason
reliability	throughput	integration failures can cascade across systems

Coordination

Protocol: orchestrated

Consumes:

Capability	From	Fallback
fix_session_management	fix-session-management	degrade

Safety

Action	Permission	Cooldown	Max Auto
port_bind_failed	autonomous	-	-
ssl_handshake_failed	autonomous	-	-
connection_refused	autonomous	-	-
connection_lost	autonomous	-	-
connection_established	autonomous	-	-
graceful_stop	autonomous	-	-

Extensions (framework-specific hints)

```yaml tech_stack: language: C++ framework: FIX Protocol Engine protocol: TCP/IP with optional TLS 1.2+ implementations: - SocketAcceptor: plain TCP server - SocketInitiator: plain TCP client - SSLSocketAcceptor: TLS server using OpenSSL - SSLSocketInitiator: TLS client using OpenSSL - ThreadedSocketAcceptor: multi-threaded variant for high-connection-count scenarios - ThreadedSocketInitiator: multi-threaded outbound variant ```