Transport API

dcc_mcp_core.TransportManager

TransportManager

Python-facing wrapper for the Rust transport layer. Bridges async operations to synchronous calls via an internal Tokio runtime.

Constructor

TransportManager(
    registry_dir: str,
    max_connections_per_dcc: int = 10,
    idle_timeout: int = 300,
    heartbeat_interval: int = 5,
    connect_timeout: int = 10,
    reconnect_max_retries: int = 3,
)

Service Discovery

Method	Returns	Description
register_service(dcc_type, host, port, version=None, scene=None, metadata=None)	str	Register a service, returns instance_id (UUID)
deregister_service(dcc_type, instance_id)	bool	Deregister a service by key
list_instances(dcc_type)	List[dict]	List all instances for a DCC type
list_all_services()	List[dict]	List all registered services
heartbeat(dcc_type, instance_id)	bool	Update heartbeat timestamp

Session Management

Method	Returns	Description
get_or_create_session(dcc_type, instance_id=None)	str	Get/create a session (UUID). If no instance_id, picks first available
get_session(session_id)	dict?	Get session info dict, or None
record_success(session_id, latency_ms)	—	Record successful request
record_error(session_id, latency_ms, error)	—	Record failed request
begin_reconnect(session_id)	int	Begin reconnection, returns backoff in ms
reconnect_success(session_id)	—	Mark reconnection as successful
close_session(session_id)	bool	Close a session
list_sessions()	List[dict]	List all active sessions
session_count()	int	Number of active sessions

Connection Pool

Method	Returns	Description
acquire_connection(dcc_type, instance_id=None)	str	Acquire connection (UUID)
release_connection(dcc_type, instance_id)	—	Release connection back to pool
pool_size()	int	Total connections in pool

Lifecycle

Method	Returns	Description
cleanup()	(int, int, int)	Returns (stale_services, closed_sessions, evicted_connections)
shutdown()	—	Graceful shutdown
is_shutdown()	bool	Check if transport is shut down

Dunder Methods

Method	Description
__repr__	TransportManager(services=N, sessions=N, pool=N)
__len__	Returns session count

Rust-Only Types

The following types are available in Rust but not directly exposed to Python:

TransportConfig

Field	Type	Default
pool	PoolConfig	—
session	SessionConfig	—
connect_timeout	Duration	10s
heartbeat_interval	Duration	5s

PoolConfig

Field	Type	Default
max_connections_per_type	usize	10
max_idle_time	Duration	300s
max_lifetime	Duration	3600s
acquire_timeout	Duration	30s

SessionConfig

Field	Type	Default
idle_timeout	Duration	300s
reconnect_max_retries	u32	3
reconnect_backoff_base	Duration	1s
max_session_lifetime	Duration	3600s
heartbeat_interval	Duration	5s

TransportError

Variant	Description
ConnectionFailed	TCP connection failed
ConnectionTimeout	Connection timed out
PoolExhausted	All connections in use
AcquireTimeout	Timeout waiting for pooled connection
ServiceNotFound	Service not in registry
ServiceAlreadyRegistered	Duplicate registration
Serialization	MessagePack serialization error
Io	IO error
RegistryFile	Registry file error
Shutdown	Transport is shut down
SessionNotFound	Session not found
InvalidSessionState	Invalid state transition
ReconnectionFailed	Max retries exceeded
Internal	Generic internal error

ServiceStatus

Value	Description
Available	Accepting connections (default)
Busy	Processing a request
Unreachable	Health check failed
ShuttingDown	Shutting down

SessionState

Value	Description
Connected	Ready for requests
Idle	Idle timeout exceeded
Reconnecting	Reconnecting after failure
Closed	Terminal state

Wire Protocol

Messages use MessagePack serialization with a 4-byte big-endian length prefix:

[4-byte length][MessagePack payload]

• Request: { id: UUID, method: String, params: Vec<u8> }
• Response: { id: UUID, success: bool, payload: Vec<u8>, error: Option<String> }