Scales globally

There are good sides and bad sides to having been in our industry for a long time. On the good side, you have seen a lot, but on the bad side, you tend to think you have seen it all. As an example, I have been riding the UI pendulum for a long time, from mainframe to 4GL client-server, then back through fat-client N-tier architecture to thin-client N-tier architecture, then slowly back again with Ajax and then bloated JavaScript clients, such as GWT, with plenty of variations along the way.

So when a young buck colleague named Mike Donovan suggested that we really needed to look at the then new thing called Angular, my initial reaction was “oh no, not again”. However, I strive to stay in touch with my inner Bruce Pujanauski. Bruce was a seasoned mainframe guru back when I was a young buck C++ programmer. We were working on a large project to port a mainframe-based ERP system to an N-tier architecture. Bruce pointed out that we were re-inventing all the same wheels that they had already perfected on the mainframe, but as far as he could tell we were on the right track. Bruce understood that the context of the industry was changing and a new generation of engineers was going to be playing a major role and he was ready to embrace the change. That moment made a lasting impression on me. So much so, that I don't think of the UI pendulum as swinging back and forth. Instead, I see it and software architecture in general as zigzagging through time, constantly adjusting to the current context.

So, I heeded Mike's recommendation and gave Angular my attention. I could see that Java UI veterans could easily feel at home with this new crop of JavaScript UI frameworks. However, I wasn't convinced of its value, until I realized that we could run this new presentation tier architecture without any servers. This was a true “what, really, wow” moment. I could deploy the UI code to AWS S3 and serve it up through the AWS CloudFront CDN. I wouldn't need an elastic load balancer (ELB) in front of a bare minimum of two EC2 instances running Apache, in turn in front of another (ELB) fronting a cluster of at least two EC2 instances running a Java App server, with all the necessary elbow grease, to run the presentation tier in just a single region. I would have to be completely nuts not to give this approach full measure.

Running the presentation tier on the edge of the cloud like this was a game changer. It enabled virtually limitless global scale, for that tier, at virtually no cost. What followed was a true “how can we do more of this” moment. How can we achieve this at the business layer and the data layer? How can we run more at the edge of the cloud? How can we easily, efficiently, and cost-effectively support multi-regional, active-active deployments? Our journey through this book will show us how. We will push the API Gateway to the edge, enforce security at the edge, cache responses at the edge, store users' personal data on devices, replicate data between components and across regions, and more. For now, suffice it to say that scalability, even global scalability, no longer keeps me awake at night.