The Application Load Balancer is a feature of Elastic Load Balancing that allows a developer to configure and route incoming end-user traffic to applications based in the Amazon Web Services (AWS) public cloud.
Application Load Balancer is a Layer 7 load balancer. It pushes traffic across multiple targets in multiple AWS Availability Zones. If a faulty application reaches Layer 7, which is the application layer of the Open System Interconnection (OSI) model. The Application Load Balancer will route traffic only to a healthy target within the cloud resource. Application Load Balancer also supports WebSocket for more communication with the underlying server.
Application Load Balancer inspects packets and creates access points to HTTP and HTTPS headers. It identifies the type of load and spreads it out to the target with higher efficiency based on application traffic flowing in HTTP messages. Application Load Balancer also conducts health checks on connected services on a per-port basis to evaluate a range of possible code and HTTP errors. A developer receives detailed metrics following the checks, including the health of microservices.
The load balancer uses listeners, which are procedures that wait for specific events to occur. A developer can add listeners to load balancers based on traffic and connection requests from clients, and then configure rules that include conditions and corresponding actions. A developer can also specify how to distribute traffic to different target groups.