Real time

1. Hard real time : all deadlines are met. missing only one deadline is overall system failure.
2. Soft real time : subset of deadlines are met. missing some deadlines is output quality degradation. guarantees maximum delays from deadlines
3. Near real time : deadlines are almost met. time delays are introduced. this is actually similar to but not the same as soft real time as near real time does not guarantees max delays.
4. Best effort : deadlines are far to be met.

Hard & soft real time : https://users.ece.cmu.edu/~koopman/des_s99/real_time/

The deadlines above are in milliseconds or microseconds.

Beyond realtime is live. (cf. wiki realtime computing)

SAML

Security Assertion Markup Language enables federated identity & SSO.

https://www.varonis.com/blog/what-is-saml/

Multi tier architecture

ประกอบด้วย 4 tiers:

client (web browser) <=> web server <=> application server (web service) <=> DB server

php running on web server สามารถเรียกใช้ web service ผ่าน PHP curl (client url) function (https://www.php.net/manual/en/book.curl.php)