Azure Functions & Serverless Computing

Editor's Notes

• #8 Azure Functions are part of the Azure Web + Mobile suite of App Services and are designed to enable the creation of small pieces of meaningful, reusable methods, easily shared across services. These serverless, event-driven methods are often referred to as “nanoservices” due to their small size. Although an Azure Function can contain quite a bit of code, they are typically designed to serve a single purpose, and respond to events in connected services.
• #9 Azure Functions can be created in most common development and scripting languages, and can be “triggered” by events in other Azure App Services, such as Web, Mobile, Logic, and API apps. Azure Functions can also be exposed via HTTP URL schemes for easy integration into legacy systems.
• #10 Azure Functions are “event-driven” meaning they run based on associated and configure events, or “triggers”. For example an Azure Function could be triggered by a simple timer, such as running a process once every 24-hours, or triggered by an event in a document management system, such as when a new document is uploaded to a SharePoint library. Azure Functions can also respond to Azure-specific events, such as an image added to a Storage Blob or a notification arriving in a Message Queue.
• #11 Although Azure Functions can be created from scratch”, the Azure Portal exposes a large number of ever-growing templates to help get developers started. These templates are typically designed with specific triggers in mind, such as a Blob Storage event, or a GitHub webhook event. Templates can easily form the basis for robust function creation, and are really designed just to get a developer started.
• #12 Timer Functions are exactly what they sound like: Functions triggered by a specific time event. Timer Functions are perfect for clean up and maintenance processes and can easily be combined with other functions for more robust scenarios. Timer Functions us CRON expressions to configure schedules. It’s a good idea to get familiar with CRON syntax, but in the meantime there are a number of tools online to help you build CRON expressions.
• #13 Data Processing Functions are triggered by activity in a datastore, such as a table, queue, or container. Data Processing Functions also typically have both “in” and “out” parameters, meaning they can accept an object as a parameter, and then process information and then return another object from within the function. This is not the same as a “return” value, as most Azure Functions either return void, or an HTTP response such as “created”, “accepted”, or “OK”.
• #14 Webhook and API Functions are designed to easily integrate with 3rd party systems, like GitHub, Office 365, and especially Microsoft PowerApps. Since Webhook and API Functions are often exposed to external or legacy systems, they typically need CORS settings managed in order to “allow” external resources to “see” and execute the function. Most Azure Logic Apps leverage Webhook and API Functions directly.
• #15 An Azure Function is really a group of a few files that work in harmony. All actual function logic resides in a “Run” file written in a language of choice. A “Project” file is similar to a project file in other technologies such as .NET Core or Universal Windows Platform and contains “secondary” assembly references such as NuGet packages. Finally a “Function” file contains information about triggers and parameters, such as locations of Storage Queue connection strings and whether the parameter is design as an “in”, “out” or “bi-directional”. Optionally, additional configuration is also found in the Function App Settings such as an API Key or database connection string.
• #16 Without bindings, an Azure Function would just be a “disconnected” algorithm without any way to serve a purpose. Bindings server to connect functions and output to other services. Some of the most common binding types and features are listed in the table, however variations and adaptations can and do exist.
• #17 Many Azure Functions are exposed via an actual URL that can be called directly from a web client or browser. When an Azure Function is not exposed via a URL its common practice to call the function from another function, such as a Timer-based Function for testing purposes only. Since Azure Functions can be nested, testing scenarios can be quite varied. For managing and testing Azure Functions that integrate with Storage Containers, Microsoft provides the Microsoft Azure Storage Explorer, as well as the Visual Studio Cloud Explorer. The Logs console in the Azure Function Designer is also a great way to view and trace function processing.