{"id":2694,"date":"2018-05-23T00:00:00","date_gmt":"2018-05-23T00:00:00","guid":{"rendered":"https:\/\/azure.microsoft.com\/blog\/serverless-real-time-notifications-in-azure-using-azure-cosmosdb"},"modified":"2023-05-11T15:39:29","modified_gmt":"2023-05-11T22:39:29","slug":"serverless-real-time-notifications-in-azure-using-azure-cosmosdb","status":"publish","type":"post","link":"https:\/\/azure.microsoft.com\/en-us\/blog\/serverless-real-time-notifications-in-azure-using-azure-cosmosdb\/","title":{"rendered":"Serverless real-time notifications in Azure using Azure #CosmosDB"},"content":{"rendered":"

\n\"header\"<\/p>\n

There were lots of announcements at the Microsoft Build 2018<\/a> conference, but one that caught my eye was the preview release of Azure SignalR, a Platform-as-a-Service (PaaS) offering that lets you implement real-time<\/strong> messages and notifications quite easily, without worrying about instances or hosts.<\/p>\n

So it made me wonder, could I build something using my favorite globally-distributed and serverless database<\/strong>, Azure Cosmos DB<\/a>, and Azure\u2019s serverless compute offering, Azure Functions<\/a>? It turns out others were interested in this topic too.<\/p>\n

Real-time, really?<\/h2>\n

For those of you that do not know, SignalR<\/a> is a library that\u2019s been around since 2013 for the ASP.NET Framework, recently rewritten for ASP.NET Core<\/a> under the name of SignalR Core<\/a>, that allows you to easily create real-time applications<\/strong> and push content to clients through the Websocket<\/strong> protocol, gracefully falling back to other alternatives depending on the client. It works great for games, dashboards\/monitoring apps, collaborative apps<\/a>, mapping\/tracking apps, or any app requiring notifications.<\/p>\n

By leveraging the Websocket<\/a> protocol, content can be pushed to clients without the overhead of opening multiple HTTP connections and over a single two-way TCP channel that is maintained for the entire session.<\/p>\n

Going serverless!<\/h2>\n

One requirement<\/strong> of SignalR was that you, the developer, had to have a host<\/strong> to manage and maintain connections with clients, usually deployed as a Web instance. In Azure, you can do it in any of the PaaS offerings like App Service and Cloud Services. While it wasn\u2019t a complex task, it still meant you had to maintain<\/strong> and ensure the service could handle a number of connections and the load based on your design and user load definitions.<\/p>\n

With Azure SignalR<\/strong>, the host is provided for you<\/strong>. You only need to connect the clients and servers to the exposed service endpoint. You can even scale the service<\/a> based on your needs transparently.<\/p>\n

If you add a serverless database <\/strong>plus Azure Functions as a serverless platform<\/strong> to run all your code, then the result would be\u2026 Serverless, Serverless everywhere!<\/p>\n

Streamlining notifications<\/h2>\n

The architecture would need:<\/p>\n