API Gateway: Layer 8 Network

An API is a set of rules that govern the exchange of data between devices. "Much of the web runs on HTTP. Smart devices, connected appliances, and automated systems all rely on HTTP to exchange API calls and data with applications and services that monitor and operate them."

It established the definition of APIs and demonstrated that APIs sit on top of the existing network stack, making them layer 8.

Now consider the definition of an API Gateway:

I could rewrite this definition to illustrate this parallel using an IPv6 gateway, but I won’t emphasize that point. The reason it’s important to recognize that the API Gateway is networking at layer 8 is to discuss its role as a strategic control point in the network architecture.

Just as the ADC became a strategic control point due to its use in routing requests, converting protocols (HTTPS to HTTP) and finding the best path (load balancing/global server load balancing), the API Gateway is quickly becoming a strategic control point in the "application" network. I use the word "scare" because it is not really a separate network, but a separate plane in the existing network stack. It is incremental, not a replacement.

Whenever an architectural construct becomes the “thing” that all traffic passes through, it becomes a strategic control point where decisions can be made. These decisions may be security related, such as redirecting requests for operational API commands through some security mechanism to ensure the legitimacy and authority of the requestor to invoke such a command. These decisions may be performance related, such as their ability to determine the “best path” based on business outcomes related to digital experience expectations. This may be availability despite performance degradation, or it may be based entirely on performance. By virtue of its architectural position in the network, the API Gateway is often the best judge of how to meet these expectations.

API Gateways are definitely becoming a “trend.” According to our research, nearly half (48%) of organizations are already using them, and a quarter (25%) plan to use them by the end of 2021.

That’s a good thing, as API usage continues to explode by the minute. A survey conducted at the end of 2020 found that “API usage will grow even more throughout 2021. The survey found that 71.1% of developers expect to use more APIs in 2021.”

The combination of digital transformation and the adoption of modern, microservices-based architectures is certainly behind this growth. For example, a 2020 Propeller Insights survey found that the sweet spot for the number of APIs per application is between 26 and 50.

So the growth is really or could be explosive because as usual, this doesn't take into account the proliferation of cloud and other operational APIs that are being exposed to manage and operate everything from IoT to network devices to management consoles.

The growth of APIs is inevitable. This growth effectively adds more traffic to the network - requests and responses - at a layer above the traditional network stack. This makes it inevitable that a network fabric will emerge to provide a way to route, secure, and manage the requests and responses that traverse that network.

That structure is the API Gateway, and it will become a strategic control point for enterprises to manage, secure, and optimize the experience for operators and consumers who (albeit unknowingly) use them.