Scale By the Bay 2018

Authors: Julien Delange & Adam Crane As of today, many applications expose their data with limited ability to query or filter fields. Often, application developers use multiple endpoints to implement behavior variability or data filtering, which is inefficient from an engineering perspective. GraphQL, a new query language, addresses this issues by allowing the end user to query the data available on the server and select only the fields of interest. Initially started by Facebook, the technology gained traction over the years to the point that several companies started to implement GraphQL endpoint. In this talk, we present a methodology for building a modern data-rich application centered around GraphQL schemas. We cover how the schema informs decisions for the rest of the application layers and unlocks new query patterns and possibilities compared to a standard REST-based or IDL-based approach. We also cover how this affects the design of data storage, using traditional storage backends (key-value, SQL). To support these themes we present a novel application (Network Health Visualizer), its data pipeline and how the implementation of its GraphQL interface guided the rest of our development process. Additionally, we cover the Twitter GraphQL API and how it fits into the data layer of Twitter infrastructure as a whole.