Serverless computing is a method of providing backend services on an as-used basis. Servers are still used, but a company that gets backend services from a serverless vendor is charged based on usage, not a fixed bandwidth or the number of servers.
What is serverless computing?
Serverless computing is a method of providing backend services on an as-used basis. A serverless provider allows users to write and deploy code without the hassle of worrying about the underlying infrastructure. A company that gets backend services from a serverless vendor is charged based on their computation and does not have to reserve and pay for a fixed bandwidth or several servers, as the service is auto-scaling. Note that despite the name serverless, physical servers are still used, but developers do not need to be aware of them.
In the early days of the web, anyone who wanted to build a web application had to own the physical hardware required to run a server, which is a cumbersome and expensive undertaking.
Then came cloud computing, where fixed numbers of servers or amounts of server space could be rented remotely. Developers and companies who rent these set units of server space generally over-purchase to ensure that a spike in traffic or activity will not exceed their monthly limits and break their applications. This means that much of the server space that gets paid for can go to waste. Cloud vendors have introduced auto-scaling models to address the issue, but even with auto-scaling, an unwanted spike in activity, such as a DDoS Attack, could be costly.
Serverless computing allows developers to purchase backend services on a flexible ‘pay-as-you-go’ basis, meaning that developers only have to pay for the services they use. This is like switching from a cell phone data plan with a monthly fixed limit to one that only charges for each data byte that gets used.
The term ‘serverless’ is somewhat misleading, as servers still provide these backend services, but the vendor handles all of the server space and infrastructure concerns. Serverless means that the developers can do their work without having to worry about servers at all.
What are backend services? What’s the difference between frontend and backend?
Application development is generally split into the front and backend realms. The front end is part of the application that users see and interact with, such as the visual layout. The backend is the part the user doesn’t see; this includes the server where the application’s files live and the database where user data and business logic persist.
For example, let’s imagine a website that sells concert tickets. When a user types a website address into the browser window, the browser sends a request to the backend server, which response with the website data. The user will then see the front end of the website, which can include content such as text, images, and form fields for the user to fill out. Users can then interact with one of the form fields on the front end to search for their favorite musical act. When the user clicks on ‘submit,’ this will trigger another request to the backend. The backend code checks its database to see if a performer with this name exists and, if so, when they will be playing next and how many tickets are available. The backend will then pass that data back to the front, and the front end will display the results in a way that makes sense to the user. Similarly, when the user creates an account and enters financial information to buy the tickets, another communication between the front and back ends will occur.
What kind of backend services can serverless computing provide?
Most serverless providers offer database and storage services to their customers, and many also have Function-as-a-Service (FaaS) platforms. With FaaS, developers can build a modular architecture, making a more scalable codebase without spending resources on maintaining the underlying backend.
What are the advantages of serverless computing?
- Lower costs – Serverless computing is generally very cost-effective, as traditional cloud providers of backend services (server allocation) often result in the user paying for unused space or idle CPU time.
- Simplified scalability – Developers using serverless architecture don’t have to worry about policies to scale up their code. The serverless vendor handles all of the scalings on demand.
- Simplified backend code – With FaaS, developers can create simple functions that independently perform a single purpose, like making an API call.
- Quicker turnaround – Serverless architecture can significantly cut time to market. Developers can add and modify code piecemeal instead of needing a complicated deployment process to roll out bug fixes and new features.
How does serverless compare to other cloud backend models?
A couple of technologies often conflated with serverless computing are Backend-as-a-Service and Platform-as-a-Service. Although they share similarities, these models do not necessarily meet the requirements of serverless.
Backend-as-a-service (BaaS) is a service model where a cloud provider offers backend services, such as data storage, so developers can focus on writing front-end code. But while serverless applications are event-driven and run on the edge, BaaS applications may not meet these requirements.
Platform-as-a-service (PaaS) is a model where developers rent all the necessary tools to develop and deploy applications from a cloud provider, including operating systems and middleware. However, PaaS applications are not as easily scalable as serverless applications. PaaS also don’t necessarily run on the edge and often have a noticeable startup delay that isn’t present in serverless applications.
Infrastructure-as-a-service (IaaS) is a catchall term for cloud vendors hosting infrastructure on behalf of their customers. IaaS providers may offer serverless functionality, but the words are not synonymous.
What is next for serverless?
Serverless computing continues evolving as serverless providers develop solutions to overcome some drawbacks. One of these drawbacks is cold starts.
Typically, when a particular serverless function has not been called in a while, the provider shuts down the function to save energy and avoid over-provisioning. The next time a user runs an application that calls that function, the serverless provider will have to spin it up fresh and start hosting it again. This startup time adds significant latency, known as a ‘cold start.’
Once the function is up and running, it will be served much more rapidly on subsequent requests (warm starts), but if the part is not requested again for a while, the process will once again go dormant. This means the following user will request that the function experience a cold start. Until recently, cold starts were considered a necessary trade-off of using serverless functions.
As more and more of the drawbacks of using serverless get addressed and the popularity of edge computing grows, we can expect to see serverless architecture becoming more widespread.
