MSDN Documentation

Developing Azure Functions

This section covers the core concepts and practices for developing Azure Functions, allowing you to build serverless applications that respond to events, run on demand, and scale automatically.

Core Concepts

• Triggers: The event that invokes your function. Examples include HTTP requests, timer schedules, queue messages, and blob storage changes.
• Bindings: Declarative ways to connect your function to other Azure services and data sources without requiring you to write complex SDK code.
• Programming Models: Understand the different ways to write your function code, including in-process and out-of-process models.
• Language Support: Azure Functions supports a variety of programming languages, including C#, JavaScript, Python, Java, PowerShell, and TypeScript.

Local Development

Develop and test your Azure Functions locally before deploying to the cloud. This improves iteration speed and simplifies debugging.

• Azure Functions Core Tools: A command-line tool that lets you run and debug Azure Functions on your local machine.
• IDE Integration: Visual Studio, Visual Studio Code, and other IDEs provide excellent support for developing Azure Functions locally.

Writing Function Code

Learn how to write the actual code for your functions. This involves handling input from triggers and interacting with bindings.

Example: HTTP Trigger (JavaScript)

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,
        body: responseMessage
    };
};
            

Example: Blob Trigger (C#)

using System;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Host;
using Microsoft.Extensions.Logging;

namespace FunctionApp1
{
    public static class BlobTriggerCSharp
    {
        [FunctionName("BlobTriggerCSharp")]
        public static void Run([BlobTrigger("samples-workitems/{name}", Connection = "AzureWebJobsStorage")] Stream myBlob, string name, ILogger log)
        {
            log.LogInformation($"C# Blob trigger function Processed blob\n Name:{name} \n Size: {myBlob.Length} Bytes");
        }
    }
}
            

Advanced Topics

• Durable Functions: Extend Azure Functions with stateful workflows and long-running orchestrations.
• Consumption vs. Premium vs. Dedicated Plans: Understand the different hosting plans and choose the one that best suits your needs.
• Function Proxies: Create a managed API layer for your Azure Functions, simplifying requests and responses.
• Custom Handlers: Use custom handlers to write functions in any language that can handle HTTP requests.