Serverless systems manage session state primarily through external storage solutions, since individual serverless functions are stateless by nature. When a user interacts with an application, the session information is typically stored in a fast and accessible data store, such as a database, cache, or a dedicated session management service. This allows the application to retrieve and maintain session state between different invocations of serverless functions, ensuring continuity in user experience.
For example, developers often use solutions like Amazon DynamoDB, Redis, or even Firebase to hold session data. When a user logs in, the serverless function can create a session record in the chosen storage and return a unique session identifier to the client, such as a JSON Web Token (JWT) or session cookie. Each subsequent request from the client can include this identifier, allowing the serverless function to look up the session data and maintain context throughout the user's interactions. This approach prevents any loss of session information when different functions are triggered in response to user actions.
Another key consideration is session timeouts and management. Developers need to implement strategies for session expiration to avoid stale data and manage the overall load on the storage system. For instance, they might set up a time-to-live (TTL) on session items in a cache like Redis, which will automatically remove expired sessions. By effectively managing session state in this way, serverless systems can provide a seamless experience for users while leveraging scalable and cost-effective architecture.