AWS's Elastic Load Balancing distributes incoming application traffic across multiple EC2 instances, in multiple Availability Zones. This increases the fault tolerance and performance of your applications. It works fine with Symfony (popular php framework). But you may get error when you run your Symfony application behind AWS Elastic Load Balancer System with HTTPS connection. If so, this may save your time.
When building in concrete5, sometimes it's hard to understand what is happening at particular points in your code's execution. This is especially true when working with Ajax since the executed code isn't even running in your browser. For these reasons and others, logging variables or entire sections of output so you can inspect them once execution has completed is a sensible thing to do during development.