Apps that Scale

Every day, companies struggle to scale critical applications. As traffic volume and data demands increase, these applications become more complicated and brittle, exposing risks and compromising availability. With the popularity of Software-as-a-Service (SaaS), scaling has never been more important.

As applications grow, two things begin to happen: they become significantly more complicated, and they handle significantly larger traffic volumes. Increased complexity means increased brittleness. More traffic means more novel and complex mechanisms to manage the traffic.

Application developers seldom build scalability into their applications from the beginning. We often think we have built in scalability, and we believe we’ve done what was necessary to let our application scale to the highest levels we can imagine. But more often than not, we find faults in our logic and in our applications. These faults appear only after we begin to see scaling problems, and that makes scaling to larger traffic volumes and larger datasets more difficult.This leads to even greater complexity and even more brittleness.

Ultimately, this scale/brittleness/scale/complexity cycle turns into a death spiral for an application, as it experiences brownouts, blackouts, and other quality-of-service and availability problems. But these are your problems. Your customers don’t care about these issues. They just want to use your application to do the job they expect it to do. If your application is down, slow, or inconsistent, customers will simply abandon it and seek out competitors that can handle their business.

You can improve the scalability of our applications, even before you begin to reach these limits. Obviously, the sooner we consider scalability in the lifecycle of an application, the easier it will be to scale. Yet we don’t want to over-architect our applications for scalability beyond what is required. At any point during the lifecycle, there are many techniques you can use to improve the scalability of your application.

How do you build for scale?

1. Track availability

Modern software must maintain a high level of availability. Customers will not tolerate outages. If your application does not function when your customer needs it, they will not remain a customer for long.

2. Shift to Microservices

Modern software requires the use of modern application architectures. Modern application architectures require moving away from monolithic applications and embracing service-based architectures.

Monolith applications are extremely hard to scale, both from a traffic scaling standpoint and from the standpoint of your ability to scale the size of your organization to work on the application. The larger the monolith, the slower it is to make changes to the application, the fewer the people who can work on it and manage it effectively, and the greater the likelihood that traffic variations and growth will negatively impact availability.

Service-oriented architectures solve these problems by providing greater flexibility in scaling based on traffic needs. In addition, they provide a scalable framework to allow larger development organizations to work on the application, allowing the applications themselves to get larger and more complex.

3. Organization Culture

You cannot build modern software unless your development organization makes use of modern processes and procedures. This includes service ownership responsibilities and development processes.

It doesn’t matter how scalable your application is; you cannot scale your application if your development organization isn’t structured to support it, or if your organization does not have the right culture to drive higher availability and greater scalability.

Organizing your teams to better support your scalability needs will create a culture that supports your application’s scaling needs.

4. Risk Management

You cannot remove all risk from a system. It just isn’t possible. All complex systems have inherent risk. Instead, we must learn to manage the risk and use risk as a tool for evaluating technical debt and making decisions on application improvements.

Understanding risk, measuring risk, and prioritizing activities based on measured risk are important tools for building highly scaled, high-availability applications.

5. Elastic Infrastructure

High availability in a modern application requires nimble scaling. We can no longer afford to have excess infrastructure capacity lying around to meet the peak needs of our application. Instead, we must dynamically allocate and consume infrastructure resources, on demand, based on our current needs.

Dynamic infrastructures, and applications that can support and optimize dynamic infrastructures, are a critical architectural component to building highly scaled, highly available applications.

Dynamic infrastructures are the cornerstone benefit of the public cloud. Utilizing the public cloud is essential to keeping your application highly available at scale.

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