What to watch out for – Designing Compute Solutions
Azure Batch is, of course, not suited to interactive applications such as websites or services that must store files locally for periods – although, as already discussed, it can output results to Azure Storage.
Service Fabric
Modern applications are often built or run as microservices, smaller components that can be scaled independently of other services. To achieve greater efficiency, it is common to run multiple services on the same VM. However, as an application will be built of numerous services, each of which needs to scale, managing, distributing, and scaling, known as orchestration, can become difficult.
Azure Service Fabric is a container orchestrator that makes the management and deployment of software packages onto scalable infrastructure easier.
The following diagram shows a typical Service Fabric architecture; applications are deployed to VMs or VM scale sets:
Figure 7.3 – Azure Service Fabric example architecture
It is particularly suited to .NET applications that would traditionally run on a virtual machine, and one of its most significant benefits is that it supports stateful services. Service Fabric powers many of Microsoft’s services, such as Azure SQL, Cosmos DB, Power BI, and others.
Tip
When building modern applications, there is often discussion around stateful and stateless applications. When a client is communicating with a backend system, such as a website, you need to keep track of those requests – for example, when you log in, how can you confirm the next request is from that same client? This is known as state. Stateless applications expect the client to track this information and provide it back to the server with every request – usually in the form of a token validated by the server. With stateful applications, the server keeps track of the client, but this requires the client to always to use the same backend server – which is more difficult when your systems are spread across multiple servers.
Using Service Fabric enables developers to build distributed systems without worrying about how those systems scale and communicate. It is an excellent choice for moving existing applications into a scalable environment without the need to completely re-architect.
What to watch out for
You will soon see that there are many similarities between Service Fabric and AKS clusters – one of the most significant differences between the two is portability. Because Service Fabric is tightly integrated into Azure and other Microsoft technologies, it may not work well if you need to move the solution to another platform.