Serverless functions: a smart approach to building realtime experiences

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Explore how you can achieve cost saving, scalability, and improved efficiency by taking advantage of Pusher Serverless Functions to execute business logic on your realtime events.


Serverless functions are a vital solution for developers seeking to increase efficiency in their business logic implementations. By eliminating the complexities of server management, functions allow you to focus on development and deployment. With inherent scalability, fault tolerance, and high availability, serverless architecture ensures optimal resource utilization while reducing overhead costs. 

In this article, we will delve into the world of serverless functions, with an emphasis on realtime messaging and data processing.

We will explore some of the benefits that functions offer and provide insights on how you can achieve cost saving, scalability, and improved efficiency when developing your apps.

The time/money equation

Time and money are crucial considerations for any engineer who wants to optimize. In order to save on both, you need to minimize time spent on non-programming tasks. Period. 

According to the Activate Developer Survey, developers allocate a significant portion of their time to managing architecture and software design, with only 2 to 4 hours dedicated to actual programming. Yikes! If you strive to maximize time programming and effectively address your end-user concerns, you’ll inevitably turn to solutions that minimize time spent on non-core tasks.

Part of architecture and software design management is of course managing servers. Using serverless functions to execute your business logic will free up valuable time and resources by removing complexities of infrastructure management. This way, you can focus solely on writing code. Additionally, functions offer significant cost-saving potential. With traditional infrastructure, you face the burden of provisioning and maintaining servers, incurring both upfront and ongoing expenses.

Ideally, you want to look for a pay-as-you-go model where you only pay for your actual usage of resources. If your goal is to avoid upfront investments in hardware and reduce operational costs, you can optimize your budget allocation and potentially invest in areas that directly impact user experience or enhance core features.

The power of functions executed on realtime events

Realtime experiences require seamless and instantaneous communication between end users, which can be achieved through serverless architectures.

Let’s take a closer look at how serverless functions can be used in combination with realtime messaging and realtime data processing: 

Realtime messaging: One key advantage of functions in realtime experiences is the ability to handle high concurrency and scale on-demand. Realtime applications often experience spikes in user activity depending on where your users are or the use case of your app. Traditional server architectures may struggle to handle a sudden influx of requests. Serverless functions are great because they are designed for scalability. They ensure that your app remains responsive and performs optimally, even during peak usage periods.

By leveraging event-driven architecture, messages can be processed and delivered in seconds, offering end users a seamless communication and messaging experience. Whether it's processing incoming data, transforming messages in flight, sending notifications, or triggering specific actions, functions can be instantly invoked based on events.

Data processing: You can use functions to optimize your data processing in realtime. Whether it’s performing realtime data analytics or handling IoT sensor data, functions can draw insights and take action with minimal delay.

The auto-scaling nature of serverless functions can accommodate high volumes of data — helping you reach your goals at the desired scale. 

A practical look at how serverless functions can be used

To put things in perspective, let’s look at some realtime app cases and the attached benefits of using serverless functions. 

Chat app:

  • Event-driven automation: Functions can be triggered by events like incoming messages or user actions, automating tasks while you focus on developing core chat functionalities.
    This allows you to automate message mutation and trigger automatic reactions such as automatically notifying users about an update, filtering profanity, translating messages to serve-multi language conversations, or highlighting chat content for a better user experience. 
  • Scale: As the number of concurrent chat users and chat activities increase, serverless functions automatically handle scale without the need for manually scaling or provisioning resources.


  • Event-driven processing: Functions can help to analyze live data events and respond programmatically. For example, triggering alerts based on your predefined settings, auditing, or aggregating large amounts of data into insightful statistics — helping you or your end users make the right decisions.  
  • Cost optimization: You can eliminate the need to provision and manage servers, freeing up budget and reducing server managing costs. You’d only pay for what you use — making real time analytics more affordable and accessible.

Keep in mind that functions use cases are unlimited and can be leveraged flexibly to match your own business logic needs. Some other function types you might want to look at implementing could include:

Security: authenticate users or ban malicious accounts from a platform

Moderation: filter live events for markers of malicious behavior

Logging: log events for storage, audit or debugging purposes

Integration: transform event capabilities via third party services

IoT sensors and devices: move complex operations off resource constrained devices and monitor real world data streams to respond to anomalies

Routing: route events to relevant downstream services 

Looking ahead, serverless functions are likely to evolve with emerging technologies such as edge computing, AI and machine learning. This will open a door for more intelligent applications, automation and predictive analytics. The future definitely holds endless possibilities.

Best practices to reduce cost and increase efficiency using serverless functions

  • Design for scalability using event-driven architecture
    Break down apps into smaller, reusable components to allow granular scaling based on specific events or triggers. This way, you can ensure optimal performance and workload.
  • Take security into consideration
    Implement end-to-end encryption, especially if dealing with sensitive data. Ensure you are using the latest security standards for all dependencies to mitigate vulnerabilities. And don't forget to set up user authentication.

Pusher Functions can be a significant asset in addressing all the aspects we've discussed in this blog post, ranging from deployment and scalability to matching security standards, cost reduction and eliminating the need for you to manage infrastructure.

Using Channels as your pub/sub messaging platform, you can take advantage of Pusher serverless functions. These are hosted on infrastructure managed by Pusher, allowing you to alter, filter, modify, and redirect events. The functions you write can be directly uploaded to the Channels system. These Pusher functions are triggered by Channels events, such as client events or presence channel events.

You can integrate Pushers Serverless Functions with other Channels features like encrypted and presence channels, user authentication, and more, depending on the functionality you require.

Ready to explore functions through Pusher Channels? sign in or sign up for a free sandbox account and get started right away with Functions docs.