Using REST APIs¶

REST stands for REpresentational State Transfer. It originally had a more abstract meaning, but has come to be a shorthand name for web sites that act a bit like python functions, taking as inputs values for certain parameters and producing outputs in the form of a long text string.

API stands for Application Programming Interface. An API specifies how an external program (an application program) can request that a program perform certain computations.

Putting the two together, a REST API specifies how external programs can make HTTP requests to a web site in order to request that some computation be carried out and data returned as output. When a website is designed to accept requests generated by other computer programs, and produce outputs to be consumed by other programs, it is sometimes called a web service, as opposed to a web site which produces output meant for humans to consume.

Of course, a web browser is just a computer program, so all requests to web sites come from other computer programs. But usually a browser requests data from a web site in order to display it directly to a human user of the browser.

Prior to the development of REST APIs, there were other ways that computer programs made remote requests to other computers on a network, asking them to perform some computation or retrieve some data. Those other techniques are still in use. REST APIs are particularly convenient, both for students and for others, because it is easy to see what is going on in a request and a response between two computers (using a web browser!), and thus it is easier to debug.

In this chapter, we will examine a common pattern used in REST APIs, where there is a base URL that defines an “endpoint”, and then additional information is appended to the URL that defines the request, and the response comes back not as HTML but as a format called JSON. Along the way, we will see some functions in python modules that are helpful for constructing the URLS and for processing the JSON formatted response.

We will also take a detour to understand a little about Unicode, the system for representing non-English characters on the Internet.