Overview Proxy Auto-Configuration (PAC) is a method used by Web browsers to select a proxy for a given URL. The method for choosing a proxy is written as a JavaScript function contained in a PAC file. This file can be hosted locally or on a network. Browsers can be configured to use the file manually. How PAC Files Work Direct all traffic through the first proxy. If it is unreachable, use the second proxy.

HTTP proxy gets a plain-text request and [in most but not all cases] sends a different HTTP request to the remote server, then returns information to the client. The specific flow of the HTTP proxy server is as follows. HTTPS proxy is a relayer, which receives special HTTP request (CONNECT verb) and builds an opaque tunnel to the destination server (which is not necessarily even an HTTPS server). Then the client sends SSL/TLS request to the server and they continue with SSL handshake and then with HTTPS (if requested).

Today we are talking about the somewhat unusual day of February 29. It comes up on the calendar only every four years. A year with a February 29 might be good news if you are paid by the day or the week. But it might be bad news if you were born on a February 29. You have to wait three years in between birthdays. In any case, American English has a term for the unusual situation.

After finish the Get Started study, I try to do some exercises to acquire a better understanding. In this appendix, These are just to get you started with practice over the concepts from the book. Practicing Comparisons Let’s practice working with value types and comparisons (Chapter 4, Pillar 3) where coercion will need to be involved. scheduleMeeting(..) should take a start time (in 24-hour format as a string “hh:mm”) and a meeting duration (number of minutes).