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# Vinyl Cache Glossary

..

  This file will be sorted automagically during formatting, so we keep the source in subject order to make sure we cover all bases.

backend

  The HTTP server vinyld is caching for. This can be any sort of device that handles HTTP requests, including, but not limited to: a webserver, a CMS, a load-balancer another vinyld, etc.

backend response

  The response specifically served from a backend to vinyld. The backend response may be manipulated in vcl_backend_response.

body

  The bytes that make up the contents of the object, vinyld does not care if they are in HTML, XML, JPEG or even EBCDIC, to vinyld they are just bytes.

client

  The program which sends vinyld an HTTP request, typically a browser, but do not forget to think about spiders, robots script-kiddies and criminals.

header

  An HTTP protocol header, like “Accept-Encoding:”.

hit

  An object vinyld delivers from cache.

master (process)

  One of the two processes in the vinyld program. The master process is a manager/nanny process which handles configuration, parameters, compilation of :term:VCL etc. but it does never get near the actual HTTP traffic.

miss

  An object vinyld fetches from the backend before it is served to the client. The object may or may not be put in the cache, that depends.

object

  The (possibly) cached version of a backend response. vinyld receives a response from the backend and creates an object, from which it may deliver cached responses to clients. If the object is created as a result of a request which is passed, it will not be stored for caching.

pass

  An object vinyld does not try to cache, but simply fetches from the backend and hands to the client.

pipe

  vinyld just moves the bytes between client and backend, it does not try to understand what they mean.

request

  What the client sends to vinyld and vinyld sends to the backend.

response

  What the backend returns to vinyld and vinyld returns to the client. When the response is stored in vinyld’s cache, we call it an object.

VCL

  Vinyl Configuration Language, a small specialized language for instructing vinyld how to behave.

vinyld (NB: with ‘d’)

  This is the main Vinyl Cache program. There is only one program, but when you run it, you will get two processes: The “master” and the “worker” (or “child”).

vinylhist

  Eye-candy program showing response time histogram in 1980s ASCII-art style.

vinyllog

  Program which presents Vinyl Cache transaction log in native format.

vinylncsa

  Program which presents Vinyl Cache transaction log in “NCSA” format.

vinylstat

  Program which presents Vinyl Cache statistics counters.

vinyltest

  Program to test vinyld’s behaviour with, simulates backend and client according to test-scripts.

vinyltop

  Program which gives real-time “top-X” list view of transaction log.

worker (process)

  The worker process is started and configured by the master process. This is the process that does all the work you actually want vinyld to do. If the worker dies, the master will try start it again, to keep your website alive.