Hi, writing a article about development cloud computing applications, and i dont know how a call cloud software, the title article is architeture and design of (eg. On demand Application), how definition i can use??i am very confused about this definition wanna know the difference of this concepts: Cloud Application,On demand application and SaaS application.
thx
These are the definitions I personally find helpful:
A cloud application is any application that runs on the cloud, i.e. it is not tied to any specific infrastructure but runs fully on virtualised services. This is an architectual distinction.
An on demand application is one where you can scale up or down the requirements (e.g. able to get extra processing capacity to deal with peak demand). This is a functional distinction which may run on a cloud but could equally well run on physical infrastructure. For example I believe IBM provides mainframes where you can turn on extra processors as needed.
A SaaS application refers to the business model by which the application is provided, i.e. rented on a service / subscription basis from another party which provides the ongoing infrastructure and maintenance. An example would be salesforce.com. This is typically done over the internet, but could be delivered through other models e.g. a dedicated server appliance.
Hence all three terms have slightly different meanings and implications. It's possible for a given application to be all three, but many will also only fall into zero, one or two of these categories.