API
APIs act as a bridge for data but a barrier for complexity. They allow two systems to speak without requiring either side to understand the internal logic of the other.
It is an invitation to collaborate without an invitation to interfere.
From a remoting perspective, the API serves as the interface for application integration, exposing server-side via communication protocols.
Definition
Remote APIs serve as the connective tissue for distributed systems. They expose well-defined endpoints that allow disparate components to collaborate on complex business processes. Whether facilitating real-time data exchanges or activating server-side processing, these interfaces transform isolated functions into integrated, automated workflows.
Design Traps
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Unlimited queries and giant responses
”Give me everything” endpoints look harmless in dev, then hit out of memory, crash, or collapse under concurrency as datasets grow.
Fix: paginate by default, enforce sane limits. -
Pagination that lies when data changes
Offset or page based pagination breaks when items are inserted or deleted between calls. Clients can miss items or see duplicates.
Fix: cursor or token based pagination for changing datasets, plus a clearly defined sort order. -
Pagination plus conditional requests edge cases
A page’s rows might stay identical, while metadata changes. Example: total pages increases. “Not modified” logic needs to account for metadata vs data, not just the row set → 100f1⁝ ETags Cache Representations, Not Rows -
Caching and invalidation pain
Conditional requests help, but there still has to be a definition of what counts as “changed” and how metadata is treated. Cache invalidation remains the classic trap.
Also: implementing conditional requests as a response filter can save bandwidth but not CPU, because the response still gets computed before being discarded. -
Response shaping creates coupling and security risks
Field lists add provider logic, widen the attack surface, and can leak internal model structure. Misspelled fields may be silently ignored, and renamed fields can break clients in odd ways. -
Response shaping with deep templates can melt infra
Nested “wish templates” get complex quickly, and deep expansions can explode result sizes and latency until timeouts appear. -
Chatty APIs vs bundling: the complexity tax shows up somewhere
Bundling reduces round trips, but adds splitting, dispatch, merging, and tougher error handling.
Gotchas: clients can’t assume execution order, partial failures need element-level error reporting, and access control per bundle element is tricky.
Worst case: coordination makes the provider stateful, which fights horizontal scaling behind load balancers.
Also: bundling + shaping + conditional requests together often buys small gains for a lot of complexity. -
Versioning
Semantic versioning works until it’s applied inconsistently, and breaking changes slip into “minor” releases.
Publishing patch versions to clients can create accidental coupling. Hiding patch numbers externally may be worth considering.
Replays and backups raise the bar: old messages can be reprocessed later, so backward compatibility becomes non-optional. -
Too generic vs too task-specific
Generic APIs can be syntactically stable but hard to learn, test, and use because complexity moves into payloads.
Task-specific APIs are easier for humans but expose many operations and change more often.
Common trap: drifting into one extreme by accident, then spending years crawling back to the middle. -
Weak error design kills operability
Unstructured errors become a long-term tax. Structured error messages improve clarity and force explicit error conditions.
Explicit error reports are a key tool for debugging real client usage mistakes. -
State changes without a state machine
If clients can trigger actions in flexible sequences, invalid or even fraudulent flows become possible unless valid transitions are enforced server-side.
Also: transactional work should align with operation boundaries, otherwise consistency becomes a ghost. -
Rate limits and billing get weird once optimization starts
After adding shaping, conditional requests, or bundling, it’s necessary to define how these count toward rate limits and pricing, or clients will feel cheated.