The next iteration of the ELB service came when AWS saw a requirement for some more advanced features for modern applications that could deliver even more flexibility of routing traffic based on layer 7 requests. The Application Load Balancer (ALB) was introduced to the layer 7 traffic shaping capability.

As with the CLB, the ALB is a highly available managed solution and provides the same features, but on top of the CLB features gives us the power of being able to target multiple backends that respond to different types of requests, including the following:

• Browser-based clients requesting https://www.example.com will get redirected to a set of frontend instances serving your website
• Mobile clients requesting https://www.example.com will get redirected to the mobile version of the website running on a separate set of frontend instances
• Browser-based clients requesting https://www.example.com/partners/ will get redirected to the partner application running on the backend
• Remote servers accessing the partner application requiring API access on https://www.example.com/partners/API/ will get redirected directly to the API service of your backend instances

The ALB is also able to connect to the following:

• Any reachable IP in the same VPC
• Any reachable IP within a peered VPC in the same region
• An EC2 instance connected to a VPC via ClassicLink
• An on-premises resource connected via VPN or an AWS Direct Connect connection