AWS Live updates architecture

What it runs through

In the order a request or a record moves through it. Each one links to the page that explains it.

Signals in a brief that point here

Phrases that, when you meet them in a scenario, mean this shape rather than another. They are the tell, and they are what an exam question is built around.

• “without polling”
• “every participant sees it immediately”
• “two-way connection”
• “live”
• “collaborative”

Learn the services in it

• AWS API GatewayA managed front door for APIs: REST, HTTP and WebSocket APIs that take each call, check who is calling, throttle it, and pass it to Lambda, another service or any HTTP backend.
• AWS LambdaRuns your code in response to events, with no servers to manage. You pay per request and by the millisecond, and a run lasts 15 minutes at most.
• AWS ElastiCacheA managed in-memory cache, Valkey, Redis OSS or Memcached, that answers repeated reads from memory so the database behind it does less.

Shapes it is easily confused with

These run through some of the same services, which is exactly why a brief that fits one can look like it fits another.

• Queue-based load levellingWhen the front takes more than the back can absorb.
• Serverless APIWhen ordinary requests, and nothing to patch.
• Cache-aside readsWhen reads vastly outnumber writes and the database feels it.