Introduction to Azure Functions

What are Azure Functions?

Azure Functions is a serverless compute service that enables you to run event-driven code without explicitly provisioning or managing infrastructure. With Azure Functions, you can build applications by writing code in your favorite language and simply uploading it. You pay only for the compute time you consume – when your code runs, not for idle infrastructure.

Key Concepts

• Event-Driven: Functions are triggered by events, such as HTTP requests, timer schedules, messages from a queue, or changes in a database.
• Serverless: You don't need to worry about managing servers, operating systems, or runtime environments. Azure handles all the infrastructure management.
• Scalable: Azure Functions automatically scales your application based on demand, ensuring high availability and performance.
• Cost-Effective: The consumption plan model means you only pay for the resources your functions consume when they are running.
• Developer Productivity: Focus on writing code, not infrastructure. Supports multiple programming languages and integrates seamlessly with other Azure services.

Common Use Cases

• Real-time data processing: Process streaming data from IoT devices or logs.
• Web APIs: Build lightweight RESTful APIs quickly.
• Scheduled tasks: Run batch jobs or scheduled operations.
• Orchestration: Coordinate workflows involving multiple Azure services.
• Microservices: Develop and deploy small, independent services.

How it Works

Azure Functions operate on a trigger-and-binding model. A trigger defines what event causes a function to execute, and bindings allow your function to connect to other Azure services and data sources easily.

Triggers

Examples of common triggers include:

• HTTP Trigger: For building web APIs or responding to webhooks.
• Timer Trigger: For executing code on a schedule.
• Blob Trigger: For reacting to changes in Azure Blob Storage.
• Queue Trigger: For processing messages from Azure Queue Storage.
• Event Hub Trigger: For processing events from event streams.

Bindings

Bindings simplify input and output operations. For example, an HTTP output binding can return a response to an HTTP request, and a Cosmos DB input binding can retrieve data from a Cosmos DB collection.

Here's a conceptual example of an HTTP-triggered function:

// Example in JavaScript (Node.js)
module.exports = async function (context, req) {
    context.log('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,
        body: responseMessage
    };
};
            

Getting Started

To start building with Azure Functions, you'll typically need:

• An Azure account.
• The Azure Functions Core Tools installed locally.
• A code editor like Visual Studio Code with the Azure Functions extension.

In the next tutorial, we'll walk you through creating your very first Azure Function.