Web, API, and Application Platform Patterns
What This Chapter Is About
Combine the capability decisions from earlier parts into a coherent customer-facing web and API architecture.
Keep one durable idea in view:
An application pattern is a composition of responsibilities along a request path, not a diagram of named services.
Sections
How the Chapter Develops
The chapter develops in this order:
Reframe patterns as reusable arrangements of responsibilities and flows.
Follow an external request through edge, protection, routing, and entry controls.
Place API, runtime, identity, secret, and data boundaries behind that entry path.
Add scaling, safe change, failure handling, observability, recovery, and cost.
Apply the completed decision model to one design and translate it through AWS and Azure lenses.
Together, these sections show that a web or API pattern is a reasoned system shape, not a provider reference diagram to copy unchanged.
What You Will Be Able to Do
By the end of this chapter, the reader should be able to:
Trace responsibilities along a public request path.
Explain why API, runtime, data, and trust boundaries may not align.
Add operational and change concerns before calling a design production-ready.
Translate one provider-neutral design into AWS and Azure without claiming false equivalence.
Key Ideas
Begin with users, request paths, trust changes, state, and failure modes.
Public entry does not require public access to every downstream component.
Runtime and data choices should follow workload behavior and ownership needs.
Reliability, observability, deployment safety, and cost are structural concerns.