Apollo HTTP Link

apollo-link-http is a foundational, terminating link within the Apollo Link ecosystem, designed to transport GraphQL queries, mutations, and subscriptions over standard HTTP. It serves as the primary method for connecting an Apollo Client instance to a GraphQL server via fetch. Currently at version 1.5.17, this package is considered stable but is part of the older `apollo-link` architecture, which has largely been superseded by integrated link implementations within `@apollo/client` v3 and newer. It supports both POST and GET requests and offers extensive options for dynamic URIs, custom headers, credentials, and fetch behavior, including per-query overrides via context. Its key differentiator is its modularity within the `apollo-link` chain, allowing it to be composed with other links for features like error handling, retries, or batching. It requires a `fetch` compatible API in the runtime environment.