405 — Not Allowed

"I’d like to this letter into the library's collection," Eli said, sliding a sealed envelope toward the slot.

"The library is right here," the clerk droned, pointing to the shelves of books behind him. "You’ve got the right place. But this is an . It is a read-only establishment. You can GET a book, you can HEAD a title, but you cannot POST a letter here. We simply don't allow that method of interaction." "But I have to leave this letter!" Eli insisted. 405 Not Allowed

"If you want to leave something," the clerk explained, "you need to go to the . That building accepts the POST method. Here, we only let people look." "I’d like to this letter into the library's

In the bustling city of Silicon Circuit, every citizen is a and every building is a Server . But this is an