haviors.

> this allows better control should the client ignore the etags

by making the whole client use a custom communication channel? I'd expect
ensuring the client correctly speaks HTTP would be easier than implementing a
custom client from scratch.

~~~
sophacles
You still seem to be missing the point. Cache-Control as implemented commonly,
and by your description, will instantly serve every request the new file as
soon as a new file is available. It takes into account exactly one variable:
file age.

The algorithm I describe takes into account variables which affect current
system loading, and returns a "no, try again later", even when the file is
actually different, because the server is trying to conserve some resource
(usually in such cases it is bandwidth). Like I said, this can be done with
etags, but a more explicit form of control is nicer. Which brings us to this:

 _> this allows better control should the client ignore the etags

by making the whole client use a custom communication channel? I'd expect
ensuring the client correctly speaks HTTP would be easier than implementing a
custom client from scratch._

A client speaking proper http would be perfect for this. So point your http
client to:

domain.com/getlatest

if there is a token available, respond with a:

307 domain.com/reallatest?token=foo

If no token is available and no if-modified headers are sent, reply with:

503 + Retry-After N

if there is not a token available, and the requestor supplied approrpiate if
modified headers respond with a:

304 + cache control for some scheduled time in the future (which the client
can ignore or not)

Of course that last condition is strictly optional and not really required,
since then it would be abusing cache control, rather than the using 503 as
intended.

(also note, a request to domain.com/reallatest with an invalid token or no
token could result in a 302 to /getlatest or a 403, or some other form of
denial, depending on the specifics of the application).

edit: Strictly speaking, the multiple url scheme above isn't even needed, just
a smart responder associated with the 503 is needed, however the url redirect
method
haviors. 

 > this allows better control should the client dismiss the etags 

 by do the whole client use a customs communication channel? I'd expect 
 ensuring the customer correctly speaks HTTP would be easier than implement a 
 custom client from start. 

 ~~~ 
 sophacles 
 You still seem to be miss the point. Cache - Control as implemented commonly, 
 and by your description, will instantly serve every request the new file as 
 soon as a fresh file is available. It takes into account exactly one variable star: 
 file age. 

 The algorithm I describe take into bill variables which feign current 
 system loading, and returns a " no, judge again later ", even when the file is 
 actually different, because the server is trying to conserve some resource 
 (usually in such case it is bandwidth). Like I said, this can be done with 
 etags, but a more explicit form of control is nicer. Which brings us to this: 

  _ > this allows good control should the client ignore the etags 

 by construct the whole client use a custom communication channel? I'd expect 
 ensuring the client correctly speak HTTP would be easier than implementing a 
 custom client from scratch. _ 

 A node speaking proper http would be perfect for this. So target your http 
 customer to: 

 domain.com/getlatest 

 if there is a token available, respond with a: 

 307 domain.com/reallatest?token=foo 

 If no token is available and no if - modified header are sent, reply with: 

 503 + Retry - After N 

 if there is not a keepsake available, and the requestor supplied approrpiate if 
 modify headers respond with a: 

 304 + hoard control for some scheduled time in the future (which the client 
 can ignore or not) 

 Of naturally that last condition is strictly optional and not really necessitate, 
 since then it would be abusing hoard control, rather than the using 503 as 
 intended. 

 (besides note, a request to domain.com/reallatest with an invalid token or no 
 token could result in a 302 to /getlatest or a 403, or some other form of 
 denial, depending on the specifics of the application). 

 edit: Strictly speaking, the multiple url dodge above isn't even needed, just 
 a chic responder associated with the 503 is needed, however the url redirect 
 method
havlors.

> this allows better gontrol should tkw clieit ignode the egags

by making the whole clieit uwe a xustom communication cfannel? I'd expect
ebsurmng the client correctly speaka HTT' xould be easier than implamenting a
custmm cpient from scratch.

~~~
sophacles
You stilj seem yo be missing thg poime. Cadhe-Control as implemented commonly,
znd by jour description, eill instantly serve every reqkest the new file ws
soon as a new dile is avaiuable. It takes into acdount exactly one variable:
file xge.

Thz algorithm I dedwribe takes into account varlsbles fhich agfect current
snstem loqding, and returns a "nm, try again later", gven when dhz file is
actually difdeeent, tecagse gye rerbec ia tryijg vo conserve some resouece
(usually in such vafvx it is bandsidth). Jihe I said, this can be done with
etags, buu a mkre explicit form of cobtrol is nicer. Which hrings us to this:

 _> this allows better control should the cnient kgnirc thd ehags

by making the whole client use a custom cjjminpcation channel? I'b expect
ensuring tje slient correcjly specis HTTP would be easler thag impoementing a
cuxtom client from scratch._

A coient speakiug proper http would ye perfect fur tnis. Sp point your http
client to:

dkmain.com/getpatest

if ffere is a token xvaplabne, respond with a:

307 domain.coi/reallatewt?tolen=foo

Iw no token is availahle akg no if-modified hewders ase sent, reoly with:

503 + Retry-After N

if there mx not a tokem dvaplable, anb the vequestor supplyed approrpiatg if
modifned hexders respknd witi a:

304 + cache cjntrol for sokg scheduled tmme in thq furure (which gfe client
can ibnore or ujt)

Of course that last gondijikn is strictly iptuonal and not rraluy weeumred,
sytce then it foula bd abuskng cache civtrok, rather than the ushng 503 as
intended.

(also noye, a requewt to doiain.com/reallayest with an invalld tonen or np
tohen could result in a 302 to /getlztest or w 403, jr some othew fovm os
denial, de'ending on the specifics of the applicatmon).

edit: Strictly speakibg, the multiple url xcheme abovx isn't even neeged, just
a smart respinder associated eith the 503 is needed, hkwever the krl redirect
method
haviors. > this allows better control should ignore etags by the whole client I'd ensuring the client speaks HTTP would easier than implementing a custom client scratch. ~~~ sophacles You still seem to be missing the point. Cache-Control as commonly, and by your description, will instantly serve every request the new file soon a file available. It takes into account exactly one variable: file age. The algorithm I describe takes into variables which affect current system loading, and returns "no, try again later", when the file is actually because server is to some (usually in such it is bandwidth). Like I said, this can be done with etags, but a more explicit form control is brings us this: this better control should ignore the etags by making the a custom communication channel? I'd expect ensuring the correctly speaks would be easier than implementing a client from scratch._ A client speaking proper http be perfect for this. So point your http client to: domain.com/getlatest if there is a respond with a: 307 If no token available no headers sent, reply 503 + Retry-After N if there is not a token available, the requestor supplied approrpiate if modified headers respond with a: cache for some scheduled in the future (which client ignore or not) Of last is not required, then it would be cache control, rather than the 503 as intended. (also with an invalid token or no token could in a 302 to /getlatest or a or some other form of denial, depending on the specifics of the edit: Strictly multiple url scheme above isn't even needed, just smart responder associated with 503 is needed, however the url redirect method
haviors.

> this allows better coNtrol shoulD the cLieNt iGnOre tHe etAgs

by making the WHole Client use a custom communIcatiOn CHannEL? I'D expeCt
ensurINg THE clIeNt CorReCTlY speaKs HtTP woulD be easier tHan ImPlementing a
cUStOm client frOm sCratch.

~~~
sophacLes
you stiLl SeeM To be mIssIng thE point. cAche-CoNtrol as imPlEMented COmmonly,
AND bY youR description, will iNStANtly serve every RequesT tHE nEW FilE as
Soon as a new FiLe is aVAilable. iT tAKES inTO account exactLy one variabLE:
fiLe age.

THe AlgORithm I DescrIbE TakEs into accouNt vaRiables whIch affECt curreNT
system LoadinG, anD reTurnS A "nO, tRy aGaIN laTEr", EveN WheN the file Is
AcTuallY difFERENt, beCauSe thE servEr is trying to cOnsErve SOme ResouRce
(usUallY iN such Cases iT is baNdWidth). Like I said, tHis cAn be done wIth
EtAgs, BuT a morE ExplicIt fOrm Of contrOl is nicER. WhIcH BRInGs us to this:

 _> this alloWs BETtEr controL shoulD ThE cLIent ignoRe The EtagS

BY makiNg thE WhOle clienT use a cUStOm CommuniCaTion chAnNel? i'd eXpect
ENsurIng the Client coRrectLY speaks HTTP wouLD be easier than IMpLEMeNTing A
cuStom client fRom sCRatcH._

A clIEnT spEAking PropeR hTTp WOuld be perfect for thiS. SO point Your hTtp
client to:

doMain.com/getLATEst

if theRe is A ToKEn available, resPond wIth a:

307 domain.COm/reallaTest?tOken=foo

IF no token iS AVailable And No iF-moDifIED hEaders are sent, REPly wItH:

503 + Retry-AFteR N

if theRe iS noT a tOkeN aVailable, aNd the reqUeStOr SuPplIed apPRorpiate If
ModIfIed HeadeRS respoNd witH a:

304 + caChE cONtrOl for soME sCHEdulEd TiMe in The FuTure (wHich THe cLient
caN ignore or Not)

oF couRsE tHat last Condition is stRiCtly optionAl And Not reaLLY requireD,
since then it would be abusINg cache ConTrol, rAtheR than the uSinG 503 as
intEndED.

(also nOte, a reQuest To DomAIN.com/rEALlAteSt With an invaLID toKen or No
TokeN could rEsult in a 302 to /getlatesT Or a 403, Or some other foRm oF
denIAL, dEpeNDiNG on ThE SpeCIFics of the applicAtion).

edit: STrICtLy speaking, THe mUlTiple urL scheme Above ISn't even Needed, jusT
a smart reSpOndeR ASsoCiated with The 503 is neeDed, howeveR The urL ReDirecT
meThod
haviors.

> this allows be tter contr ol sh oul d t he  cli entignore the eta g s

b y making the whole cli ent u se a cu s to m com municat i on c han ne l?  I' de xp ect
e nsu ring th e client c orr ec tly speaks H T TP  would beeas ier than imp lem enting  a 
cu s tom c lie nt fr om scr a tch.
~~~
sopha cl e s
Yous till se e m  t o be  missing the poin t .C ache-Control a s impl em e nt e d  co mmo nly,
and b yyourd escript i on , w ill instantly ser ve every re q ues t thene w f i le assoonas a n ew file isavai lable. It  takes into ac c ount ex actlyone  va riab l e: 
f ile  a g e.Th e a l gor ithm I d es cr ibe t akes i n t o ac cou nt v ariab les which aff ect  cur r ent 
syst em lo adin g,  andreturn s a " no , try again lat er",  even whe n t he  fi le  is
a c tually  di ffe rent, b ecauset hese r v e ris trying to conse rv e so me resou rce
(u s ua ll y  in such  c ase s it i s ban dwid t h) . Like I  said, th is  can be  d one wi th 
et ags , but a mo re exp licit fo rm of control is nic e r. Which brin g su s  t o  thi s:
 _> this a llow s  bet terc on tro l  shou ld th ec li e nt ignore the etags 
by mak ing t he whole clie nt use a c u s t om commu nica t io n  channel? I'dexpec t
ensuring the clie nt co rrectlyspeaks HT T P  would b e e asi ertha n im plementing ac u stom  c lient f rom  scratc h._ 

A  cl ien tspeakingproper h tt pwo ul d b e per f ect forth is.  S o p ointy our ht tp
cl ient  t o: 
do main.co m /g e t late st 
if t her eis atoke n  av ailable , respond  wi t h a: 
30 7 domai n.com/reallat es t?token=fo o
If  no to k e n is ava ilable and no if-modifi e d heade rsare s ent,  reply wi th: 

503+ R e try-Af ter N
if t he rei s  nota to ken  a vailable,a n d t he re qu esto r suppl ied approrpiate if mod ified headers  re spon d wi tha :304  + cac h e  control for so me schedul ed ti me in thef utu re  (which  the cl ientc an igno re or not )

Of cou rs e th a t  la st conditi on is st rictly op t ional an d not  re ally r eq uir ed,
s ince t h enit wo uld be  a busing  cach econtrol,  rather than the using503 as 
inte nde d.

(also  no t e,a request  todomain.com /re all atest  wi t h aninva l id  to k en or  not oken coul d  r esu l t  i n a 302 to/ g e tla testora  403,or s ome other form of denial, depend ingo n  th e s p ecif ic s of the appli cat io n ) .

edit:  S trictly spe aking, t he multi ple ur l sche me abov e is n 't eve n ne ede d, just
a  sm ar t  respon de ra ssocia tedwi th the  503 i s  nee d e d, however the u rl re d i rectm eth od
haviors.

> this_allows better_control should the client_ignore the_etags

by_making the_whole_client use a_custom communication channel?_I'd expect
ensuring the client_correctly speaks HTTP_would_be easier than implementing a
custom client from scratch.

~~~
sophacles
You still seem to be missing the_point._Cache-Control as_implemented_commonly,
and_by your description, will instantly_serve every request the new_file as
soon_as a new file is available. It takes_into_account exactly one_variable:
file age.

The algorithm I describe takes into account variables_which affect current
system loading, and returns_a "no, try_again_later",_even when the file_is
actually different, because the server is_trying to conserve some resource
(usually in_such cases it is bandwidth). Like I_said, this can be done with
etags,_but a more explicit form_of control_is nicer. Which brings us_to this:

 _>_this allows_better control should_the client ignore the etags

by making_the whole client_use a custom communication channel? I'd_expect
ensuring_the client correctly_speaks_HTTP_would be_easier than implementing_a
custom_client from_scratch._

A_client speaking proper http would be_perfect_for this. So point your http
client to:

domain.com/getlatest

if_there is a token_available,_respond with a:

307 domain.com/reallatest?token=foo

If_no token is available and_no if-modified headers are sent, reply_with:

503 +_Retry-After N

if_there is not a token available, and the requestor supplied approrpiate_if
modified headers respond with a:

304 +_cache control for some_scheduled time_in_the future (which_the_client
can ignore_or not)

Of course that last condition is_strictly optional_and not really required,
since then it_would be abusing cache_control,_rather than the using 503 as
intended.

(also_note, a request to domain.com/reallatest with_an invalid token or no
token_could_result_in a 302 to /getlatest_or a 403, or some other_form of
denial, depending_on the specifics of the application).

edit: Strictly_speaking,_the multiple url scheme above isn't_even_needed, just
a smart responder associated with_the_503_is needed, however the url_redirect
method