If your work involves getting to know and developing application programming interfaces (APIs), you will eventually come across two related terms: API emulation and API virtualization. Both terms are quite common in the field of API development, although emulation is a term that’s been intech parlance for longer. Both are also related in that they are time-tested methods for building and running software applications. But is this where the similarities end? Both are very different processes and cannot be used interchangeably. 

So, what distinguishes an API emulation from an API virtualization? How should one choose between the two? Here’s a brief explainer on both API emulation and API virtualization that should serve as a good background for open API mocking for developers

What Are The Differences Between API Virtualization And API Emulation? 

Emulation is meant to mimic the environment of a different operating system (OS). The best two examples to illustrate how this works are an Android emulator on what was originally a Windows device, or the emulator of a phased-out gaming console (such as a GameBoy Advance or a PSX) on a computer. 

Just as it would for any of these situations, an API emulation is engineered to work on a hardware platform for which it wasn’t originally designed. Thus, an emulator can be incredibly useful when modeling older API-related hardware and software on much newer platforms. It is a viable tool to keep older, but still functional, the technologies out of obsolescence.  

In contrast, virtualization involves running one whole operating system on top of another. API virtualization will be able to run accurately regardless of the physical layout or location it’s dispatched in. The computer that an API virtualization is run on will then be split into multiple isolated servers that have different hard disk, RAM, CPU, and network requirements. To a rookie developer or decision-maker in the API team, these requirements may be daunting at first.  

However, the beauty of having a virtualization is that its servers can function independently—regardless of being used in computers in the same network. The virtualization thus splits into different controlled, encapsulated computing environments that can otherwise run smoothly. Ultimately, virtualization will give developers a great idea of how the API will work shortly before it’s launched to the public. 

API Virtualization Vs. API Emulation: Deciding On The Better Choice

Both methods have their respective pros and cons. They each provide significant value in the world of software development. But here are a couple of things that you should take into consideration when you’re deciding between the two. 

  • Cost-wise, running an API emulation is much cheaper than running an API virtualization. An emulation also demands fewer requirements for hardware, which means that it consumes less RAM and less hard disk space. This is because the emulation runs an application on an OS, as opposed to an API virtualization running a whole OS on top of another one. However, working with emulation also involves a steep learning curve. The software is admittedly not very easy for developers to figure out. Plus, there are fewer chances that the software will run 100% the way they’d want it from outside of its native environment.   
  • In contrast, API virtualizations are typically costlier and heavier on resources. One example of this is that they demand more hardware, such as more RAM. But the big upside of an API virtualization is that it will be run in its own native environment—something that cannot be said of an emulation. API virtualization also has a seamless quality to it. You’ll be running the application just like it would run in a standard OS installation. Thus, you’ll see it operate in a way that hews closer to your expectations.  

In the end, it depends on which complex problem demands either of these complex solutions. One decision may be better than another for the API that you have in mind. As long as you are better equipped to understand these differences, then your choices will reflect what’s best for your API.