4 Aug 2015
In the previous post in this series, we discovered that setting up a server before you even boot it is not only possible, but gives enormous productivity rewards in a cloud architecture. In this post, we look at the four essential principles of designing your app for the cloud.
Using a cloud architecture places extra constraints on app developers. These constraints cannot be worked around, and therefore app developers must get to grips with them before they start designing their apps.
Because the constraints are often unusual and unintuitive, it is worth also understanding the context behind the constraints. Why are they necessary? How do they improve the reliability of applications? Are there no alternatives? With these questions answered, an app developer can plan more confidently, knowing that they are taking the optimum path.
All of the core constraints emerge from one fundamental principle: cloud computing must account for random failures. To cope with this you will need multiple servers, and when you have multiple servers you also need a strategy for setting up and maintaining these servers with as little effort and as few subsequent interventions as possible. Such strategies are said to belong to the cattle model, because they contrast with the usual non-cloud method of dealing with servers as something like pets.