API gateway
An API gateway is an intermediary that provides an entry point for client requests to backend APIs or services and routes or otherwise mediates those requests.
Authorization in Action
An API gateway is a service that receives, routes, and often governs requests to backend APIs.
- How it is used
- Centralizes authorization enforcement for incoming API traffic before requests reach backend services.
- How deep it goes
- Works through validation, PARC normalization, Cedar evaluation, forwarding or blocking, and coverage limits; defers gateway implementation details.
- Examples
- Uses a Manager Dashboard salary request, BI Explorer delegated access, and a Task App integration request.
- What you can do after
- Evaluate/understand how a gateway validates requests, obtains policy decisions, and enforces API access at the edge.
Effective Platform Engineering
An API gateway is a service that receives API traffic and applies gateway functions such as routing, access management, and developer credential handling.
- How it is used
- Provides a controlled external entry point for APIs used by third-party developers.
- How deep it goes
- Explains DNS-to-gateway routing and adoption trade-offs, but defers gateway implementation details.
- Examples
- Uses api.epetech.io, delegated hosted zones, and platform traffic paths as concrete infrastructure examples.
- What you can do after
- Evaluate when external API consumers justify a gateway instead of existing platform capabilities.
Read how Effective Platform Engineering explains API gateway →
Automating API Delivery
An API gateway is a service that acts as a central entry point for API traffic, routing requests to backend services while enforcing cross-cutting policies.
- How it is used
- Provides a public entry point for API products while routing requests to backend microservices and applying shared policies.
- How deep it goes
- Works through declarative routing and authentication configuration, then discusses contract validation; does not teach a gateway technology comprehensively.
- Examples
- Uses a Kong catalog route with Host and x-api-key headers, plus OpenAPI request and response validation cases.
- What you can do after
- Operate/configure it by routing a Kong endpoint to a backend and evaluating gateway-generated behavior against the API reference.
Bootstrapping Microservices, Second Edition: With Docker, Kubernetes, GitHub Actions, and Terraform
An architectural component that serves as an entry point between clients and backend services.
- How it is used
- Deploys the gateway as the customer-facing entry point, frontend host, REST API, and HTTP forwarding layer for backend microservices.
- How deep it goes
- Explains frontend serving, REST routing, streaming, authentication, and gateway topology, while deferring advanced multi-service route composition.
- Examples
- Demonstrates FlixTube’s /api/video route forwarding a streamed response from video-streaming to the browser.
- What you can do after
- Operate/configure a gateway that exposes frontend routes, forwards backend requests, and separates client access from internal services.
Spring in Action, Sixth Edition
A gateway interface is an interface whose methods provide an application-facing entry point for sending messages into an integration flow.
- How it is used
- Provides an application-facing entry point for submitting data to an integration flow and optionally receiving its result.
- How deep it goes
- Explains interface generation, channels, payloads, headers, and one-way or two-way calls through concrete Java examples.
- Examples
- Uses FileWriterGateway for file output and UpperCaseGateway with a Java DSL transformer for returned uppercase text.
- What you can do after
- Build a Spring Integration interface that sends payloads and headers into named channels and optionally returns a flow response.
Read how Spring in Action, Sixth Edition explains API gateway →
Microsoft Azure in Action
An API gateway is an intermediary service that receives client API requests and routes or manages them for backend services while presenting a stable external interface.
- How it is used
- Routes client requests to backend APIs while preserving a stable public interface during internal changes.
- How deep it goes
- Explains request flow, abstraction, service components, and HTTP integration, but defers detailed API Management capabilities.
- Examples
- Demonstrates Function App integration, an HTTP-triggered Logic App, Blob Storage retrieval, tweeting, and Azure CLI provisioning.
- What you can do after
- Operate/configure Azure API Management to expose serverless HTTP workflows through a gateway and consider request authentication.
Related concepts
- rate limituses · A rate limit is a bound on the frequency or volume of operations permitted within a defined interval, scope, or concurrency limit.
- authenticationuses · Authentication is the process of establishing or verifying the identity of a user, service, device, or other communicating entity.
- contractuses · An API contract is a specification of the operations, data, and behavioral expectations that govern interactions between software components.
- service meshalternative to · A service mesh is an infrastructure layer that manages communication and cross-cutting concerns such as traffic control, security, and observability between distributed services.
- reverse proxykind of · A reverse proxy is a server-side intermediary that receives client requests, forwards them to backend servers or services, and relays their responses to clients.
These guides are generated from the text of Manning books by Manning's knowledge graph and link to the sections they draw on. The full books are available on liveBook and at manning.com.