There are many ways to classify cloud service offerings. The most basic is to relate them to the traditional systems stack. This gives rise to terms such as ’Infrastructure as a Service’ (IaaS), ’Platform as a Service’ (PaaS) and ’Software as a Service’ (SaaS), which are generally considered to relate to the hardware, middleware and application layers respectively. However, it is sometimes helpful to take a more functional view as follows:
Business application services
It is in this area that the term ‘Software as a Service’ (SaaS) was originally coined. Services at this level are typically focused on the delivery of complete business functionality, e.g. CRM, ERP, etc.
Hosted productivity tools
Services here are more concerned with horizontal capability ranging from desktop suites for end users, through to modelling, development and project management tools for analysts and developers.
Spearheaded initially by hosted email and web conferencing, the number of services offerings in this area has exploded to include full unified communications and/or social media (directories, blogs, wikis, etc).
Trading community services
As supply chain automation has gathered momentum in some industry sectors, services have emerged aimed at facilitating the way in which customers and suppliers collaborate and transact electronically.
Myriad services exist which do not provide complete business functionality but ‘plug into’ existing applications to enhance or extend them. Examples include everything from mapping to credit checking.
Application platform services
As an alternative to consuming pre-built services from external providers, application platform services provide development and runtime environments which allow custom applications to be built and hosted online.
Sometimes, you simply want somewhere for your own software to run and store its data. This is the realm of utility services, which are essentially about providing raw compute and storage resources.
This often overlooked but highly important category is where we find services concerned with online backup, archiving, security (e.g. email filtering), etc., and even full blown monitoring and management tools.