Microsoft Azure Documentation

Azure Functions Overview

Azure Functions is a serverless compute service that lets you run code without provisioning or managing infrastructure. With Azure Functions, you can build applications by connecting various services and resources, both in Azure and third-party services.

Azure Functions is an event-driven, compute-on-demand experience that is ideal for scenarios like:

• Processing asynchronous tasks: Respond to messages from queues or topics.
• Scheduled tasks: Run batch jobs or perform recurring operations.
• Building web APIs: Create lightweight REST APIs.
• Integrating with other services: Trigger code based on events from Azure services or external sources.

How Azure Functions Works

Azure Functions operate on a simple concept: you write code (a "function") that is triggered by a specific event. This event could be an HTTP request, a new message on a queue, a file upload, or a timer. The Azure Functions platform then handles the execution of your code, scaling it as needed, and you only pay for the time your code is actually running.

Triggers and Bindings

Triggers and bindings are the core concepts that enable Azure Functions to connect to other services and respond to events:

• Triggers: Define how a function is invoked. Each function must have exactly one trigger. Examples include HTTP triggers, Timer triggers, Queue triggers, and Blob storage triggers.
• Bindings: Allow you to declaratively connect your function to data and services without writing custom integration code. Bindings can be used to inject input data into your function or to write output data from your function to other services.

Common Use Cases

Azure Functions are versatile and can be used for a wide range of applications:

• Real-time data processing: Process data streams from IoT devices or social media.
• Background processing: Handle long-running or resource-intensive tasks in the background.
• Microservices: Build small, independent services that can be deployed and scaled individually.
• Chatbots and virtual assistants: Power the logic behind conversational interfaces.

Getting Started

You can get started with Azure Functions in several ways:

• Azure Portal: Create and manage functions directly through the web interface.
• Azure CLI: Use command-line tools for automation and scripting.
• Visual Studio Code: Develop and debug functions locally with extensions.
• Visual Studio: A full-featured IDE for developing Azure Functions.

For a quick start, you can create your first function using the Azure Portal quickstart guide.

Example: HTTP Trigger

Here's a simple example of an HTTP-triggered function written in Node.js:

module.exports = async function (context, req) {
    context.log('JavaScript HTTP trigger function processed a request.');

    const name = (req.query.name || (req.body && req.body.name));
    const responseMessage = name
        ? 'Hello, ' + name + '! This HTTP triggered function executed successfully.'
        : 'This HTTP triggered function executed successfully. Pass a name in the query string or in the request body for a personalized response.';

    context.res = {
        // status: 200, /* Defaults to 200 */
        body: responseMessage
    };
};

This function, when triggered by an HTTP request, checks for a 'name' parameter in the query string or request body and returns a personalized greeting.

Pricing

Azure Functions offers a consumption plan where you are billed based on the number of executions and the compute time consumed. There are also dedicated plans for scenarios requiring predictable pricing and performance.

Learn more about Azure Functions pricing.

Next Steps

Now that you have an overview, consider exploring:

• How to create your first Azure Function
• Understanding Triggers and Bindings in detail
• Serverless Architectures with Azure Functions