My last blog entry was to illustrate some concerns that I have encountered when one is to develop an application to Windows Azure. So that comes as a bit of an oversight. I was looking at a world where there are no existing applications. So I backtracked a bit and will need to deliver a separate blog for Migrating or converting an existing web application to Windows Azure. Because 99% of the web applications out there are of course already existing.
But before we dive into that, I believe it will only be prudent to first give a definition of what an application built or migrated to Windows Azure should look like; and to define the scope of what a migration is.
First, the scope. Migration, as defined is the movement from one place to another. Not coexistence. As simple as that, we define what migration is. The existing web application will be MOVED from one location to another, with no turning back.
Then we define what is an application built for Windows Azure. It is very often that we hear people refer to an application on Windows Azure as a “Cloud Application”. Which is fair enough, as Windows Azure is, Microsoft’s cloud platform service. But I must state clearly, that not all applications running on Windows Azure were built for Windows Azure, hence, I would not consider them as cloud applications.
A cloud application, is one that was engineered and built in such a way that it will not run on any other platform other than the cloud. It will also take advantage of, and leverage everything that the cloud has to offer, such as Scaling, Multi-tenancy, CDNs, blob storage etc. If the application is not built as such, I will not call that said application as a Cloud Application or an application built for Windows Azure.
Simply put, an application must be deployed to Windows Azure, use the services offered (like Web Roles, Worker Roles, Cloud Storage etc) in the proper way, to be considered as a cloud application.
As I was writing this blog entry, I stumbled upon a webpage that illustrates everything I want to illustrate and more. J
So here it is.