cloud computing

• Software as a service (SAAS) (e.g google drawing)

accessibale from any pc on internet 

• Platform as a service (PAAS) (e.g google app engine )

allow application build on cloud

private or public deployment

tools and language are limited by the vendor

risk of vendor lock-in (cannot move to another platform)

• infrastructure as a service (iaas)  (e.g )

allow existing application to run on a cloud suppliers's hardware