OpenStack Swift

Chapter 4. Swift Basics

Amanda Plimpton

In Chapter 3 you learned about the architecture of Swift and how it stores data. In this final chapter of Part I, we’ll introduce you to the basics of accessing data in Swift. We’ll show you how to use cURL, a command-line tool, to perform simple operations on your Swift cluster. In Part II of this book we will go more deeply into the API, introduce a few client libraries, explore some of Swift’s advanced features, and learn how to build middleware with Swift.

Talking to the Cluster: The Swift API

Swift, like its animal totem, spends much of its time in motion. There are incoming requests to put data into the cluster, which result in multiple copies of the data being written to different nodes. There are also requests to get data out of the cluster, perhaps to restore a backup or to serve up content to websites or online games. For each request, Swift has to check who is making the request and whether it is allowed, before handling the request itself and responding. In addition to all that, there are the different server and consistency processes swarming behind the scenes, looking after the data. All this activity requires communication and coordination.

As mentioned in the previous chapter, the proxy server process is the only part of the Swift cluster that communicates with external clients. This is because only the proxy server process implements the Swift API. At this point, we can simply say that the Swift API is an HTTP-based set of rules ...