Explain the process of creating a custom server in Next.js.
Instruction: Detail the steps required to create a custom server in a Next.js application, including potential use cases.
Context: This question aims to assess the candidate's knowledge on extending Next.js with a custom server setup, highlighting their ability to integrate custom server-side functionality.
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Use a custom Next.js server only when the integrated routing and server features cannot meet a concrete requirement. Ordinary API handlers, authentication, redirects or a separate backend do not automatically require one. Confirm that the deployment supports your long-running Node entry point.
In an existing Next.js project with its dependencies installed, save this as server.cjs...