1.2 Where the cloud came from

Work through these

• Mainframe time-sharing, client-server, and the return of the centralised machine

  Computing began centrally with time-shared mainframes, moved out to desktops, and then came back to the centre. Seeing that loop makes the cloud look like a swing of an old pendulum rather than an invention.

• Grid computing, utility computing, autonomic computing and service-oriented architecture as the four roots

  Four earlier ideas fed into what became cloud computing, each contributing a piece: shared distributed resources, metered consumption, self-management, and composable services. Recognising the ancestors makes the vocabulary less arbitrary.

• What changed around 2006: cheap bandwidth, commodity hardware, and virtualization that finally worked

  The cloud became possible when three things arrived together: bandwidth got cheap, ordinary hardware got good enough, and virtualization finally performed well. No single one of them would have been enough.

• Why the same idea failed as the application service provider model in 1999

  The same business idea was tried and failed years earlier, and the reasons it failed are exactly the three conditions above. It is the clearest demonstration that timing, not concept, was the constraint.