Blockchain Programming with Hyperledger Composer and Fabric

Uptime is the proportion of time a service answers requests, quoted in nines, and a service level agreement is the contract clause setting out how that proportion is counted and what the provider owes when it falls short.

Kubernetes is an open-source system that runs containers across a cluster of machines, keeping the number and placement of running copies matched to a declared desired state, and restarting, rescheduling and scaling them without a person intervening.

Shared hosting puts your website on a machine that is simultaneously running hundreds of other people's, pooling its processor, memory and disk between all of you, which is both why it costs so little and why your speed partly depends on strangers.

Git is a distributed version control system that records the history of a set of files as a graph of snapshots, lets many people work on branches of that history at once, and merges their work back together.

HTTP is the request-and-response protocol of the web: a client sends a method, a path and headers, a server answers with a status code, headers and a body, and each exchange stands alone unless the two sides agree to carry state in a header.

A REST API exposes an application's data as resources at stable addresses and lets clients read and change them with HTTP's standard methods and status codes, so that the protocol itself carries most of the meaning.