What Is Sticky Session Load Balancing? What Do You Mean By "Session Affinity"?
Câu trả lời What Is Sticky Session Load Balancing? What Do You Mean By "Session Affinity"?
Sticky session load balancing, also known as session affinity, is a method used in load balancing to ensure that all requests from a particular user during a session are directed to the same server. This technique is particularly useful in environments where the user's session state is stored locally on a specific server.
Understanding Sticky Sessions
Sticky sessions are a key component in managing user sessions in a distributed server environment. When a user first makes a request to a server, a session is created and stored on that server. To maintain continuity and state across subsequent requests, sticky session load balancing ensures that all further requests from that user are routed to the same server. This is typically achieved by using a unique identifier, such as a session cookie, that the load balancer reads and uses to direct requests to the appropriate server[1][2][3][4].
How Sticky Sessions Work
Initial Request: A user makes an initial request to a web application.
Session Creation: The server handling this request creates a session and possibly returns a session cookie to the client.
Cookie Storage: The client stores this cookie and sends it along with subsequent requests.
Request Routing: The load balancer reads the cookie and routes the requests to the same server that handled the initial request, thus maintaining session persistence[3][4].
Configuration and Management
Configuring sticky sessions involves setting parameters such as cookie name, domain, path, expiration, and security settings. These settings can typically be managed through the load balancer's configuration[1][4]. For example, in some systems, you can define whether the sticky session is enabled or disabled, the type of session cookie used, and the failure policy in case the designated server is unavailable[1].
Advantages and Disadvantages
Advantages:
Consistency: Users experience a consistent interaction as their session data does not need to be recreated or transferred between servers.
Performance: Reduces the load on backend servers by minimizing data replication and synchronization across servers[2][3].
