AWS Lambda's pricing model is "pay as you go", so the customers pay only for the computing resources used. This makes the service very cost-efficient, not to mention a free trial period. In fact, the users pay for the used memory, the number of processed code requests and the code execution time rounded up by 100 milliseconds. Just compare it with the hourly EC2 billing rate and witness the granularity and level of control available when using AWS Lambda. Instead of 24/7 availability common for IaaS, PaaS and SaaS cloud pyramid layers, AWS Lambda is event-driven. The code executes only when it's needed and consumes zero resources when not triggered. Obviously, this is a huge benefit for applications that are quiet for a long time and then have to meet the demand for resources during the peaks of usage.
Lambda has a setting called the "Number of concurrent requests", which allows it to scale nearly instantly to a huge number of parallel code execution processes. Downscale is as simple — the unneeded functions stop running automatically once the code is executed.
Lambdas are the best way to represent small function objects. Don’t use anonymous classes for function objects unless you have to create instances of types that aren’t functional interfaces
If you are really interested in functional programming, look for posts by Pierre‑Yves Saumont, who has written a book about Functional Programming in Java.
"So functional programming is writing programs with no intentional side effects by which I mean side effects that are part of the expected outcome of the program. There should also be as few non-intentional side effects as possible."
So is going to be Modern Java in Action
end to end tests in any microservice is not exactly the same as an end to end test in a monolith application; you are still testing the whole service, but keeping a controlled environment, where the test only depends on components within the boundary of service
Securing DevOps explores how the techniques of DevOps and Security should be applied together to make cloud services safer.