Using Express with GraphQL – How to create a GraphQL server with Node.js/Express` demonstrates how to use Apollo Server as middleware on an existing HTTP server, specifically with Express.js. The process involves installing the necessary packages and setting up a schema using GraphQL schema language. The resulting GraphQL API can be served at `http://localhost:4000/graphql`, offering advantages such as serving both REST and GraphQL simultaneously and utilizing Node.js middleware for common problems like rate-limiting and security. However, this approach requires more boilerplate than using Apollo Server directly, but performance concerns are minimal due to the wrapper nature of Apollo Server-express over Apollo Server.