scadalink-design/deprecated/lmxproxy/docs/requirements/Component-SessionManager.md

Component: SessionManager

Purpose

Tracks active client sessions, mapping session IDs to client metadata. Provides session creation, validation, and termination for the gRPC service layer.

Location

src/ZB.MOM.WW.LmxProxy.Host/Sessions/SessionManager.cs

Responsibilities

• Create new sessions with unique identifiers when clients connect.
• Validate session IDs on every data operation.
• Track session metadata (client ID, API key, connection time, last activity).
• Terminate sessions on client disconnect.
• Provide session listing for monitoring and status reporting.

1. Session Storage

• Sessions are stored in a ConcurrentDictionary<string, SessionInfo> (lock-free, thread-safe).
• Session state is in-memory only — all sessions are lost on service restart.
• ActiveSessionCount property returns the current count of tracked sessions.

2. Session Lifecycle

2.1 Creation

CreateSession(clientId, apiKey):

• Generates a unique session ID: Guid.NewGuid().ToString("N") (32-character lowercase hex string, no hyphens).
• Creates a SessionInfo record with ConnectedAt and LastActivity set to DateTime.UtcNow.
• Stores the session in the dictionary.
• Returns the session ID to the client.

2.2 Validation

ValidateSession(sessionId):

• Looks up the session ID in the dictionary.
• If found, updates LastActivity to DateTime.UtcNow and returns true.
• If not found, returns false.

2.3 Termination

TerminateSession(sessionId):

• Removes the session from the dictionary.
• Returns true if the session existed, false otherwise.

2.4 Query

• GetSession(sessionId) — Returns SessionInfo or null if not found.
• GetAllSessions() — Returns IReadOnlyList<SessionInfo> snapshot of all active sessions.

3. SessionInfo

Field	Type	Description
SessionId	string	32-character hex GUID
ClientId	string	Client-provided identifier
ApiKey	string	API key used for authentication
ConnectedAt	DateTime	UTC time of session creation
LastActivity	DateTime	UTC time of last operation (updated on each validation)
ConnectedSinceUtcTicks	long	ConnectedAt.Ticks for gRPC response serialization

4. Disposal

Dispose() clears all sessions from the dictionary. No notifications are sent to connected clients.

Dependencies

None. SessionManager is a standalone in-memory store with no external dependencies.

Interactions

• GrpcServer calls CreateSession on Connect, ValidateSession on every data operation, and TerminateSession on Disconnect.
• HealthAndMetrics reads ActiveSessionCount for health check data.
• StatusReportService reads session information for the status dashboard.