If you have a "true microservices architecture" as the article comments, you have a time budget for every request from the front end, through the graph of calls

If you have a "true microservices architecture" as the article comments, you have a time budget for every request from the front end, through the graph of calls on the back-end. Let's imagine a call-graph budget of 300ms. Every hop after the request lands on the back end takes a bite of that. Let's imagine a straight stack of calls three deep with no branching. Front-end makes a RESTful API call to Service A. Service A calls B, B calls C, and C queries a database. Diving down to the bottom, the database call + networking will take 50ms (it's a big query), service C spends 5ms filtering, and another 10ms reorganizing the data into its response format and returns. 65ms eaten. Service B deserializes (3ms) and acts on the data (10ms), then serializes the response (2ms). 80ms eaten. Service A gets this back and chews on it for a bit to put it into shape for the front end. There's also a layer of proxies and caches the request and response goes through, so another 20 ms here. 100ms! Great! We're under budget (because we're not counting network latency back to the UI)! Now imagine, that for every one of these hops, we add a 10ms call to a session service, and processing time (hopefully tiny) to review, and error handling. We've also only covered happy path, we've not considered call retries, branching calls to resolve additional data, each with a +10ms check for that session. Now that time budget is starting to chafe. Validation of signed tokens with claims eliminates that 10ms tax on every call, and it is a big deal. How do I know? I work on a system with hundreds of microservices. We use JWTs for back-end authentication. Thank goodness the article clears us to use JWTs. :)