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Season of mists and mellow

fruitfulness,

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Everything You Wanted to

Know

About Writing Async,Concurrent HTT

A!!s in "ava

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Agenda

#ostly this$

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Agenda

And this$

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Agenda

And this$

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What 0rog1

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What 0rog1

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What 0rog1

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What 0rog1

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SERVE BINARIES FOR A LIVI

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CONCURRENT DOWNLOADS

Y U NO SUPPORT THEM?!

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2e3uirements

4!arallel 5le 6ownloads

4arallel 5le !arts4interru!t)!ause)resume

4rogress events4Chec%sums caching

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0irst Association for 7concurrent

downloader8

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9uc%y day$ 6ownload managerwritten in 'ava:

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ONE DOES NOT SIMPLY

EMBED JDM

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9et;s loo% if we can use it:

t;s an a!!, not a lib

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WANT CONCURRENT DOWNLO

WRITE IT YOURSELF

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WHY WONT YOU JUST

USE URLCONNECTION?

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"ava(net(urlconnection

/( Bloc%ing streams

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What we;re loo%ing for

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What is >T going to ta%e

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Welcome to the reactor

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4 !attern for lightweight

concurrency

4 Event driven

4Threads reuse

4 Dses nonbloc%ing >o

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riginal !attern

htt!$))www(dre(vanderbilt(edu)Fschmidt)60)reactorsiemens(!df

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Guess the author by thediagram

htt!$))gee(cs(oswego(edu)dl)c!'

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In Java,Reactor means

NIO

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Selector as a multi!leer

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"ava version 2egistering

SocketChannel channel=

SocketChannel.open();

socketChannel.connect(new

InetSocketAddress("http://remote.com

", 80));

...Selector selector = Selector.open();

channel.configureBlocking(false);

SelectionKey k=

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"ava version 6is!atcher

while (!Thread.interrupted()) {

selector.select();

Set selected =selector.selectedKeys();

Iterator it =

selected.iterator();

while (it.hasNext())

SelectionKey k= (SelectionKey)

(it.next();

((Runnable)

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Handling reactor events is com!le

4=eed to maintain state

4Bu@ering 4 assemblingchun%s

4Coordinating async events

HTTP NIO FRAMWORKS

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HTTP NIO FRAMWORKS

DO THE HEAVY LIFTING

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=io libraries

4#ost of them are servers

4=etty, griIIly, etc(

4A!ache #ina

4A!ache HTT com!onentsasyncclient

4=ing htt! client

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4Client and server nio

library4Evolved from netty

49atest release ctober

-

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=io libraries

4#ost of them are servers

4=etty, griIIly, etc

4A!ache #ina

4A!ache HTT com!onentsasyncclient

4=ing htt! client

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=ing;s async htt! client

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Here it is:

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HAC Conce!ts

42e3uest !roducer

42es!onse consumer

try (CloseableHttpAsyncClient asyncHttpClient = HttpAsyncClients.createDefault()) {

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asyncHttpClient.start();Futurefuture = asyncHttpClient.execute(

HttpAsyncMethods.createet("http://oss.jfrog.org/api/system/ping")!newAsyncByteConsumer() {

"#$errideprotected void onResponseRecei$ed(final HttpResponse response) {

%yste&.out.println(response.'et%tatusine().'etReasonhrase());*

"#$errideprotected voidonByteReceived(final Char+u,,er bu,! final -#Control ioctrl) { *

"#$errideprotected void releaseResources() { *

"#$errideprotectedHttpResponse buildResult(final HttpContext context) {return (HttpResponse) context.'etAttribute("http.response");

*

*!null);

HttpResponse response = future.get();*

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Choosing between ning and htt!asyncclient

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PAll !roblems in com!uterscience can be solved byanother level of

indirectionP 6avidWheeler

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pulic interface " ttp#rovider$ ow nload" andler{

void onResponseRecei$ed(int statusCode! M ap< %trin'!ist< %trin'> > headers);

oolean on+ytesRecei$ed(+yte+u,,er bu,);

void onFailed(/hro0 able error);

void onCanceled();

void onCo& pleted();*

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Head to head

0eature)9ibrary

=ing client Htt! Async Client

#aturity Good Qery new ?early

-

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erformance1

Small 5le #edium 5le 9arge 5le

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2fc-R

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Confused1

" t d t % *

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"ust read some stac%over*ow?and im!rove your re! as you go

for

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discoveringthat range

header islost on

redirect

HTTP WAR STORIES

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Vuestion:

What should

be contentlength when

usingcom!ression1

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htt!s$))github(com)htt!-)htt!-s!ec)issues)+R

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Vuestion:

Why when redirected to C6=all the chun%s start from Iero1

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HttpAsyncClient+uilder builder = HttpAsyncClients.custo& ();11 add redirect strate'y that copies 2ran'e2 headers! i, exist

uilder.setRedirect%trategy(ne0 $ efaultRedirect%trategy(){" # $erridepublic Http3riRe4uest 'etRedirect(HttpRe4uest re4uest! HttpResponse

response! HttpContext context)Http3riRe4uest redirectRe4uest = super.'etRedirect(re4uest! response!

context);11 copy 2Ran'e2 headers! i, existHeader56 ran'eHeaders = re4uest.'etHeaders(HttpHeaders.RA78);

i, (ran'eHeaders 9= null) {,or (Header header : ran'eHeaders) {

redirectRe&uest.add" eader(header);

**return redirectRe4uest;

**);

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Vuestion:

How many

simultaneousconnections should

> o!en1

HTTP 1 1 GOES LIKE:

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HTTP 1.1 GOES LIKE:

CAN YOU PLEASE LIMIT

TO CONNECTIONS?

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BROWSERS GO LIKE:

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URL ENCODING?

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URL ENCODING?

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Vuestion:

What;s

wrongwith the

followingcode1

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public static StringencodeDrl?String urlStr D29Encoder(encode?urlStr, "UTF-"N

(((O

6ecoded D29s cannot be

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6ecoded D29s cannot bereencoded to the same form

http:11exa& ple.co& 14uery= ab= = c

Cannot be decoded bac a,ter it 0 asencoded:

http:11exa& ple.co& 14uery= a ?@b= = c

6on;t use
http://example.com/?query=a&b==chttp://example.com/?query=a&b==chttp://example.com/?query=a&b==chttp://example.com/?query=a&b==chttp://example.com/?query=a&b==chttp://example.com/?query=a&b==chttp://example.com/?query=a&b==c

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6on t use'ava(net(D29Encoder

7Dtility class for HT#9 formencoding( This class contains static

methods for converting a String tothe application/x-www-form-urlencoded #>#E format(

0or more information about HT#9form encoding, consult the HT#9s!eci5cation(8

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AHC Alternatives

or'.apache.http.client.utils.3R-+uilder

or'.apache.http.client.utils.3R8ncoded3tils

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Vuestion:

How do >

close asoc%et

correctly1

How hard can it be to close a

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How hard can it be to close asoc%et1

h f % l i

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The art of soc%et closing

htt!$))www(safariboo%sonline(com)library)view)htt!the

Halfclosed$ no new

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Half closed$ no newcustomers

=ever bloc% in soc%et

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=ever bloc% in soc%etclose?

The other side e!ects

you to clean u! nicely >t will give u! on time

outYou will wait ?forever

I ALWAYS CLOSE

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I ALWAYS CLOSE

CONNECTIONS

AND WHEN I DO IT I USE

TRY"WITH"RESOURCES

2 b 1

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2emember1

V ti :

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Vuestion:

How can >write 5le!artsconcurrently1

4 Write to se!arate 5les

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Write to se!arate 5les,

combine on 5nish4 Write to same 5le,

see%ing to the right!osition

WHY WONT YOU JUST USE

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WHY WON T YOU JUST USE

JAVA IO RANDOMACCESSFILE?!

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DSE 0il Ch l

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DSE 0ileChannel

>m!lements %eeable+yteChannel

a$a.nio.channels.'ileChannelB w rite( a$a.nio.+yte+u,,er src! lon'

position)

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0il 9 %i

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0ile 9oc%ing

0ile loc%ing 9e els

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0ile loc%ing 9evels

4Q# level

4S level

S level 0ile loc%ing

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S level 0ile loc%ing

#ulti!le downloader instanceswriting to the same 5le

=eeded for writing$

artial download 5le ersistent download !rogress

S 9evel 0ile 9oc%ing

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Fileoc loc = ,ileChannel.tryoc(); 11 onshared: (! on'.M ADEA38!

false)if (loc = = null) {

throw new#$erlappin'Fileoc8xception(); * return loc;*

gEclusive

S 9evel 0ile 9oc%ing 4

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private Fileoc loc(FileChannel ,ileChannel)throw s-# 8xception {

Fileoc loc = ,ileChannel.tryoc(on'.M AX_VALUEG!!false); if (loc = = null) { throw new # $erlappin'Fileoc8xception(); * return loc;*

gAdvisory eclusive

WT01:

Q# 9evel 0ile 9oc%ing

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WHY DO YOU NEEDLOCKS

IF YOU WRITE TO

DIFFERENT PARTS OF


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4revent same Q# threads writing tothe 5le when we started closing it

4Closing se3uence$42elease 5le loc%s

4Close channels

42ename a 5le to itXs 5nal name?remove (!art

4Erase !rogress info


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ReentrantReadI riteoc.Readoc w rite*o'ile+oc,= r0 l.readoc();ReentrantReadI riteoc.I riteoc close'ile+oc,=r0 l.0 riteoc();

public $oid close() thro0 s -# 8xception { this.close'ile+oc,.loc,();*

public int 0 rite(int part-ndex! +yte+u,,er bu,) { i, (9this.w rite*o'ile+oc,.try+oc,()) { thro0 ne0 -lle'al%tate8xception(2File is bein'closed2);

*

What;s net1

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What s net1

htt!)-

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htt!)-

4 #ostly standardiIing GoogleXs s!dy4 Header com!ression

4 multi!leing4 rioritiIation

4 Server !ush

4 n the way clear some stu@4 E(g( com!ressed content length

Ease the load

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Ease the load

9in%s:

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9in%s:

2T0#$ 20C -R

=o Than% you:
http://www.w3.org/Protocols/rfc2616http://www.amazon.com/HTTP-The-Definitive-Guide-Guides/dp/1565925092http://www.safaribooksonline.com/library/view/http-the-definitive/1565925092/http://jeewanthad.blogspot.co.il/2013/02/reactor-pattern-explained-part-1.htmlhttp://gee.cs.oswego.edu/dl/cpjslides/nio.pdfhttp://gee.cs.oswego.edu/dl/cpjslides/nio.pdfhttp://jeewanthad.blogspot.co.il/2013/02/reactor-pattern-explained-part-1.htmlhttp://www.safaribooksonline.com/library/view/http-the-definitive/1565925092/http://www.amazon.com/HTTP-The-Definitive-Guide-Guides/dp/1565925092http://www.w3.org/Protocols/rfc2616

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=o, Than% you:

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A Vuic% Tourof Logos

The 9ogical A!!eal

So what eactly is logic1 Who

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So what eactly is logic1 Whocares1>nformally, logic is about saying things that ma&esense.You can thin% of it in that way if you li%e(

7>tXs !retty sunny today, so you should wear sunscreen(8

0ormally, logic is the art of arguing 4not li%e a 5ght or debate, but by

using the information we already%now to draw new and usefulconclusions(

7>f itXs sunny today, you should wear sunscreen(>ndeed it is sunny today(

Therefore, you should wear sunscreen(8

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7But wait( That 'ust loo%ed li%e the

eact same thing you said before,you hac%(8

ell, yes( But thatXs how an argument loo%s in starm: You can brea% down anyargument into thisat ma%es it easier to thin% about(

>f itXs sunny today, you should wear sunscre

>t is sunny today(

Therefore, you should wear sunscreen(

remises)

givens

Conclusion

?remises always come 5rst, and the conclusion always come

How about a more com!le

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How about a more com!leargument1

t also has seeds(

/( >f a fruit is fuIIy, itXs either a %iwi or a !each(

+( eaches have a !itN they donXt have seeds(.( So the fruit canXt be a !each(

R( So the fruit must be a %iwi(

Which of the above sentences is a conclusion

How about a more com!le

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How about a more com!leargument1

t also has seeds(

/( >f a fruit is fuIIy, itXs either a %iwi or a !each(

+( eaches have a !itN they donXt have seeds(.( So the fruit canXt be a !each(

R( So the fruit must be a %iwi(

Good logic lets us cobble together lots ofdi@erent !ieces of information, and tell from

them whatXsprobably or defnitely true.

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But what counts as 7good logic81

That argument was good ?made sense, becausethe conclusion followed from the !remises( WeXllsee what this means in a moment(

Why donXt we loo% at a badargument1

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Some !eo!le have fallen o@ cli@s and lived(

erefore, if > 'um! o@ this cli@, > will de5nitely be

7Comeon(Whatcould

!ossibly

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Some !eo!le have fallen o@ cli@s and lived(

erefore, if > 'um! o@ this cli@, > will de5nitely be

his argument is wea%( Although the !remiseis tXs easy to thin% of ways ?very !ainful ways that

nclusioncould be false( The easiest way to s!ogic is to do 'ust that$ try to thin% of another wa

hiloso!hers call these counterexamples(

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9etXs loo% at two %inds ofarguments(

'.6eductive reasoning$ All interns can breathe 5re( Sohili! can breathe 5re(

>s there a !iece of the !uIIle missing1

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9etXs loo% at two %inds of arguments(

'.6eductive reasoning$

All interns can breathe 5re( hili!is an intern( So hili! canbreathe 5re(

ometimes you may encounter 7hidden8 statemnd ideas, which the writer snea%s in but doesnXty outright(

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'.6eductive reasoning$

All interns can breathe 5re( hili!is an intern( So hili! canbreathe 5re(

Are the !remisestrue1

>f so, then the conclusionXs100% guaranteed true(=o getting around it:

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(.>nductive reasoning$

> touched a stove and it burned me( > did this

5fty times, and the same thing ha!!ened(Sothe

net time > touch the stove, it will burn me(

Are the !remisestrue1

>f so, then the conclusionXsprobably true( There mightstill be ece!tions(

9>KE WHAT1

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How is this useful to me1

9i%e #r( #organ said, the ability toma%e strong logical arguments will

become more and more im!ortantlater on in high school and college(

athos and ethos are still valuable:But your audience will be a lot betterat 3uestioning them( 9ogos is handybecause, if you use it well, it canXt

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How is this useful to me1

But even better is the su!er!ower to s!ot weaklogic(

=et time you watch TQ or go online ?with your!arentsX !ermission, of course, try to %ee! trac%of how many di@erent arguments are being!itched to you by ads( How much info is given to

ou1 How much is left out1

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What time is it1

Adven wait, no( Activity time:

air o@ into grou!s of four( Each grou! will receive an eamf a !oor argument ?these may be either inductive or deduc

ith your grou!, you will have . minutes to try to come u!ne countere)ample one way in which the argumentould be wrong, even if the !remises are de5nitely true(

o%e it full of holes:lso, choose a grou! re!resentative to tell us your reasonin

>tXs K to imagine unli%ely or weird e!lanationsNonXt be afraid to thin% outside the bo(

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Some eam!les$

RGU!"#$7> !ulled an allnighter studying for last wee%Xs bst, and > ended u! with an A( Tiredness must ma%e me sma

&U"#!R$What if you got an A because you actually studiedr maybe the test was going to be easy for you all along1

RGU!"#$7>f > !lay with 6adXs !ower tools, heXll yell at me

ut 6ad isyelling at me for something( So > guess > must halayed with the !ower tools(8

&U"#!R$What if heXs yelling at you for a di@erent reason$cratching the car, or hammerthrowing the cat onto the roo

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*ohn +eats

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PTo ,utumnP is a !oemby English2omantic!oet"ohn Keats?/< ctober

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PTo AutumnP is the 5nal wor% in a grou!of !oems %nown as

KeatsXs P

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The imagery is richly achieved throughthe !ersoni5cationof Autumn
http://en.wikipedia.org/wiki/Personificationhttp://en.wikipedia.org/wiki/Personification

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!oem

Season of mists and mellowfruitfulness

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fruitfulness,

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lose bosom-friend of thematuring sun

onspiring with him how to loadand bless

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ith fruit the vines that roundthe thatch-eves run

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To bend with a!!les the mossXd

cottage trees

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cottagetrees,

,nd $ll all fruit withripeness to the core

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To swell the gourd, and !lum! thehaIel shells

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With a sweet %ernelN to setbudding more

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budding more,

And still more, later *owers forthe bees

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the bees,

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-their clammy cells.

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Who hath not seen thee oft amidthy store1

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thy store1

Sometimes whoever see%sabroad may 5nd

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abroad may 5nd

Thee sitting careless on a granary*oor

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*oor,

Thy hair softlifted by thewinnowing wind

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winnowing wind

r on a halfrea!;d furrowsound aslee!

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sound aslee!,

6rowsed with the fume of !o!!ies, whilethy hoo%

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thy hoo%

S!ares the net swath and all itstwinZd *owers$

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twinZd *owers$

And sometimes li%e a gleaner thoudost %ee!

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dost %ee!

Steady thy laden head across abroo%N

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broo%N

3patient loo&3

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Thou watchest the last ooIings,hours by hours(

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y

Where are the songs of S!ring1 Ay,where are they1

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e e a e ey

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en n a wa u c o r e smagnats mourn

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-sallows3 borne aloft

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r sin&ing as the light windives or dies

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sin%ing

And fullgrown lambs loud bleat fromhilly bournN

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y N

edgecric%ets singN and now withreble soft

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lose bosom-friend of thematuring sun

onspiring with him how to load andbless

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ith fruit the vines that round the thatch-eves run

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To bend with a!!les the mossXd cottage

trees,

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,nd $ll all fruit with ripeness to the core

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To swell the gourd, and !lum! thehaIel shells

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With a sweet %ernelN to set buddingmore,

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And still more, later *owers for thebees,

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Dntil they thin% warm days will nevercease,

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Who hath not seen thee oft amid thystore1

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Sometimes whoever see%s abroadmay 5nd

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Thee sitting careless on a granary*oor,

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Thy hair softlifted by the winnowingwind

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r on a halfrea!;d furrow soundaslee!,

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6rowsed with the fume of !o!!ies, while thyhoo%

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S!ares the net swath and all itstwinZd *owers$

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And sometimes li%e a gleaner thoudost %ee!

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Steady thy laden head across abroo%N

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- 3

patient loo&3

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Thou watchest the last ooIings, hoursby hours(

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Where are the songs of S!ring1 Ay, whereare they1

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While barrZd clouds bloom the softdying day

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And touch the stubble!lains withrosy hueN

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en n a wa u c o r e sma gna smourn

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r sin&ing as the light windives or dies

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sin%ing

And fullgrown lambs loud bleat from hillybournN

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The redbreast whistles from a gardencroftN

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An gat er ng swa ows tw tter n t es%ies(

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Trusses

Element 0ormulation by QirtualWor%

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Dse virtual wor% to derive elementsti@ness matri based on assumeddis!lacements

rinci!le of virtual wor% states that if ageneral structure that is in e3uilibriumwith its a!!lied forces deforms due to aset of small com!atible virtual

dis!lacements, the virtual wor% done ise3ual to its virtual strain energy ofinternal stresses(

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We now assume a sim!le dis!lacementfunction to de5ne the dis!lacement ofevery material !oint in the element(

Dsually use low order !olynomials

Hereu J a< \ a-x

uis aial dis!lacement

a

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The constants are found by im!osingthe %nown nodal dis!lacements ui, u(

at nodes iand(

ui ) a< * a-xi

u( ) a< * a-x(

ui, u(are nodal dis!lacements

xi, (are nodal coordinates

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Strain is given by

where ]B^ is a matri relating strainto nodal dis!lacement ?matri of

derivatives of sha!e function

[ ] [ ]

du d[N]{d} [B]{d}

dx dx

1B 1 1

L

= = =

=

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=ow ) !, )) !]B^dOE

Stress and strain are constant in a

member 6e5ne internal virtual strain energy

for a set of virtual dis!lacements

dO to beT

e ! " # d =

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- J virtual strain- J stress level at e3uilibrium

d-J volume

Qirtual wor% of nodal forces is'eJ dO

#O

Then, virtual wor% is given by

( ) { } { }T T

d$ d % =

Substituting and rearranging gives

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Canceling dO#gives ]%^dOJ/Owhere

0or thermal !roblem

( ) ( )T ToT T T T T

o

[B]{ d} &[B]{d} & d { d} {% }

{ d} [B] &[B]{d}d { d} [B] & d$ { d} {% }

=

= +

[ ] [ ] [ ]' B B= T

V

E dV

{ } { } o 1( % &)1 = +

oT =

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for a truss we get

this formulation method also a!!liesto -d and /d elements

[ ]' =

EA

L

1 1

1 1

cedure for 6irect Sti@ness #ethod ?6is!lacement #eth

1. *is+retize into %inite elements, denti%y nodes, elements

and num-er them in order

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and num-er them in order.

2. *e$elop element sti%%ness matri+es [e] %or all the

elements.

/. )ssem-le element sti%%ness matri+es to 0et the 0lo-alsti%%ness matrix "[] [e]#. The size o% o% 0lo-al

sti%%ness matrix total d.o.% o% the stru+ture in+ludin0 at

-oundary nodes. )ssem-ly is done -y mat+hin0 element

displa+ement 3ith 0lo-al displa+ements. )lso de$elopappropriate %or+e $e+tor "-y addin0 element %or+e $e+tors#

su+h that e4uation o% the type [] {u}{(} is o-tained.

5. )pply 'inemati+ -oundary +onditions. 6ithout applyin0

- d diti [ ] ill - i l " i i

rocedure for 6irect Sti@ness #ethod

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-oundary +onditions, [] 3ill -e sin0ular. "minimum

num-er o% -oundary +onditions re4uired is to arrest 78i0id

Body9 displa+ements#.

:. ;ol$e %or un'no3n displa+ements {u} " {u} [] n+e displa+ements are determined %ind

"a# rea+tions -y pi+'in0 up appropriate ro3s %rom thee4uation {(}[] {u}, "-# (ind element %or+es {%}[e]

{ue}, "+# &lement stresses 0i$en -y {e} [*][B]{ue}.

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1 2 3

F1

, u1

F2, u2 F3, u3

Boundary Conditions

u1=0, u2=0

-A, 9, E A, 9, E

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[ ]

2 ?2

)& ?2 2@1 ?1L

?1 1

=

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2eactions

{ } [ ]

{ } [ ]

1

/

A)& PL 2P

( 2 ?2 A 1L /)& /

A

A)& PL P

( A ?1 1 1L /)& /

A

= =

= =

Element 0orces

f< f-&lement 1

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A, 9, E

-A, 9, E

A, 9, E

1 1

2 2

21

/2

% u1 ?12)&% ?1 1 uL

1 ?1 A 2p /2)& PL

?1 1 1 2p /L /)&&lement 2

u% 1 ?1)&

u% ?1 1L

1 ?1)&

?1L

=

=

=

1 p /PL

1 A p //)&

=

2P

/

2P

/

P

/

P

/

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u< u- u- u/

[ ] [ ]1 2

&lement 1 &lement 2

1 1 1 1)& )&

1 1 1 1L L

= =

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6irect Element 0ormulation

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truss element acts li%e

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AJ cross section area !J modulus of elasticity

LJ length

k AE

L=

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Assume dis!lacements are muchsmaller than overall geometry vertical dis!lacements of horiIontal

member !roduce no vertical force

Sti@ness matri is written in localelement coordinates aligned alongelement ais

want sti@ness matri for arbitraryorientation

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rotate coordinate systems usingrotation matri ]2^ dis!lacement com!onents in global

coordinates are related to

dis!lacement com!onents in localcoordinates by dOJ]2^dO dO J dis!lacement in global

coordinates d;O J dis!lacement in local element

coordinates

AE

y

i jui ui

vi vj

pi

Pj

ij

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L

x

st

'

A1 +olumn '

A

=

rd

'

A/ +olumn

'

A

=

A

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th A5 +olumnA

A

=

nd

A

A2 +olumn

A

A

=

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start with member onxais, elemente3uations are

or %;Od;OJf;O =ote thatye3uations are all Iero

i i

i i

C C

C C

u D p D' A ' A

$ D 4 DA A A A

u D p D' A ' A$ D 4 DA A A A

=

x

y y

pj uj

vj

j

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pi ui

x

i

vi

i i i i i i

i i i i i i

at node i

u D u +os" # $ sin" # p D p +os" # 4 sin" #

$ D u sin" # $ +os" # 4 D 4 sin" # 4 +os" #

= + = +

= + = +

At node i

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A similar matri can be obtained at node '

i i

i i

u D u+os sin$ D sin +os $

=

i i

i i

p D p+os sin4 D sin +os 4

=

i i

i i

C C

C

u D u+os sin A A

$ D $sin +os A A

u D uA A +os sin

A A sin +os$ D

=

C$

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#atri ]2^ is$+os sin

sin +os

+os sin

sin +os

A A

A A

A A

A A

A A

A A

A A

A A

=

c s

s c

c s

s c

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Similarly , force com!onents arerelated by O J ]2^O

9ocal force dis!lacement relation is

]%;^d;O J f;O global force dis!lacement relation is]%^]2^dO J ]2^O

using fact that ]2^

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