Ever since applications started moving data records, we’ve needed ways to annotate those records with formatting instructions. Many of these record notation formats are familiar to developers. For example, according to the IETF, JSON “defines a small set of formatting rules for the portable representation of structured data.” In practical terms, JSON makes it possible to describe value pairs, arrays, or a series of values as a human-readable document.
Similarly, the prolific XML markup language makes it possible to encode data into a format that is both human and machine-readable. Without formatting instructions provided by JSON and XML, machines would lack the context necessary to express and analyze documents. However, what happens when data cannot be expressed as a document?