Evolving Archetecture

Evolving architecturemake development easy and your site faster

Leo Lapworth @ YAPC::EU 2007http://leo.cuckoo.org/

http://leo.cuckoo.org


Covering

Covering

How running websites has evolved

Covering


Servers improved

Covering


Servers improved

Architecture improved

Covering


Servers improved


Development tools improved

Covering


Servers improved


Development tools improved

Code (and code libraries) got better

but not...

but not...

Covering anything in depth

Concepts stolen from


Mod_perl guide


Mod_perl guide

Léon Brocard


Mod_perl guide

Léon Brocard

Six Apart


Mod_perl guide

Léon Brocard

Six Apart

Yahoo!


Mod_perl guide

Léon Brocard

Six Apart

Yahoo!

+ many other people...


Mod_perl guide

Léon Brocard

Six Apart

Yahoo!

+ many other people...

... this is social Perl

Templates

TemplatesAn example of how things have improved...

Recognise this?

Recognise this?use CGI;$q = CGI->new();$name = $q->param('name');print $q->header('text/html');$link = 'http://foo.com/';print "<html><head><title>HTML and code together</title></head><body>";print "<a href=\"$link/$name\">";print "Click here $name</a><br />\n";print "<table>" . join("\n", map { "<tr><td>$_</td></tr>"} qw(this is hard to maintain));print "</table>";

http://foo.com/'

http://foo.com/'

How about...

How about...

Now, was it cellspacing, or cellpadding I need for ie4.02?

and...

and...

I'm a developer, not a designer. I shouldn't have to know this £@$%!

Use templates...

Use templates...

use Template;

Code, not HTML

Code, not HTMLuse CGI;use Template;

$q = CGI->new();print $q->header('text/html');my %vals = ( name = $q->param('name'),);

$template = Template->new({ INCLUDE => '/path/' });$template->process('hello.html',\%vals);

I just code, I have clean code and I don't

have to know HTML or browser compatibility

issues

Simple changes make a huge difference

Servers

Single server

Single server

Internet

Web server

(static & dynamic)

Database server

All editing

Lots of...

and...

I thought I only changed one thing, but

it's still broken

1 live server 1 development server

1 live server 1 development server

Internet

Live server

Web server

(static & dynamic)

Database server

All editing

Development server

Web server

(static & dynamic)

Database server

Does not solve:

What did I change last?

Who changed what / when?

You need...

You need...

Version control & docs


Use SVK with Subversion




Clkao - SVK



Clkao - SVK

Use Trac (http://trac.edgewall.org)


http://trac.edgewall.org



Clkao - SVK

Use Trac (http://trac.edgewall.org) - wiki





Clkao - SVK

Use Trac (http://trac.edgewall.org) - wiki- task tracker





Clkao - SVK

Use Trac (http://trac.edgewall.org) - wiki- task tracker- web interface to Subversion




Tests - all you need on one slide


Write tests, write tests often



Run tests, run tests often




Tests are good




Tests are good

Found a bug? - write the test that replicates it. You know it's fixed when your test passes




Tests are good

Found a bug? - write the test that replicates it. You know it's fixed when your test passes

Use Test::More, and then test some more!

Making your site faster

mod_perl

mod_perl

Code caching (loaded/compiled once)

mod_perl


Server only spends time running the code

mod_perl



Apache::Registry for old/existing code

mod_perl




Apache::SizeLimit (safety net)

mod_perl





Set it high

mod_perl





Set it high

Check it

Front/back end split

Front/back end split

Internet

Front end

Web server

(static & proxy to

application server)

Development

server

Back end

(application server)

Web server

(dynamic)

Database server

Slow

Fast

or put another way...


Internetslow and

demanding kids

(users)


Internetslow and

demanding kids

(users)

Front endDinner-ladies - good at

serving precooked (static) food. Can order from à la carte chefs

and then serve

Canteen


Internetslow and

demanding kids

(users)

Back endChefs - good at

making à la carte (dynamic) food

Kitchen

Front endDinner-ladies - good at

serving precooked (static) food. Can order from à la carte chefs

and then serve

Canteen

Internet

Front end

Web server

(static & proxy to

application server)

Development

server

Back end


Web server

(dynamic)

Database server

Slow

Fast

Internet

Front end

Web server

(static & proxy to

application server)

Development

server

Back end


Web server

(dynamic)

Database server

Slow

Fast

Speed up the frequent...


Are you re-creating the same objects/data structures again and again?


Are you re-creating the same objects/data structures again and again?

Can this information persist for a period of time?

Add caching

Add caching

Persisting data for a period of time

Add caching


Simple to implement:

Add caching



Does cache exist?

Add caching



Does cache exist?

YES -> retrieve it and return it

Add caching



Does cache exist?

YES -> retrieve it and return it

NO -> create data/object, store in cache and return it

Things you might cache


Search result sets (a list of ids)



Individual items



Individual items

Look-ups of information from a database



Individual items

Look-ups of information from a database

Fetching of information from external sources

Centralise

Centralise

Put caching methods in one package

Centralise

Put caching methods in one package

Put any generic methods in a package

We now have a cache

Internet

Front end

Web server

(static & proxy to

application server)

Development

server

Back end


Web server

(dynamic)

Database server

Slow

Fast

Cache

We now have a cache

Internet

Front end

Web server

(static & proxy to

application server)

Development

server

Back end


Web server

(dynamic)

Database server

Slow

Fast

CacheCache

Adding in the cache...


InternetKids


InternetKids

Front endDinner-ladies


InternetKids

Back endChefs



CacheMagic

freezer

InternetKids

Back endChefs


Coping with more traffic


Internet

Front end

Web server

(static & proxy

to application

server)

Stage server

Back end


Web server

(dynamic)

Development

server (in the

office)

Database

server

Back end


Web server

(dynamic)


Internet

Front end

Web server

(static & proxy

to application

server)

Stage server

Back end


Web server

(dynamic)

Development

server (in the

office)

Database

server

Back end


Web server

(dynamic)

That's two separate disks

That's two separate disks

Internet

Front end

Web server

(static & proxy

to application

server)

Stage server

Back end


Web server

(dynamic)

Development

server (in the

office)

Database

server

Back end


Web server

(dynamic)Cache

Cache

Second kitchen, two freezers...


InternetKids


InternetKids



InternetKids

Back endChefs

Kitchen 1

Kitchen 2



InternetKids

Back endChefs

Kitchen 1

Kitchen 2

CacheFreezers


We want a cache across servers...


EnterMemcache


EnterMemcache

See Léon Brocard's talkat 16:20 for the details

Internet

Front end

Web server

(static & proxy

to application

server)

Stage server

Back end


Web server

(dynamic)

Development

server (in the

office)

Database

server

Back end


Web server

(dynamic)

Cache

Shared freezer

Shared freezer

InternetKids

Shared freezer

InternetKids


Shared freezer

InternetKids Back end

Chefs

Kitchen 1

Kitchen 2


Shared freezer


Chefs

Kitchen 1

Kitchen 2

CacheFreezer


Maintaining servers

Maintaining servers

Keep all servers identical where possible

Maintaining servers


Package your code (e.g. .debs)

Maintaining servers



Centralise your crontabs and configuration files (and put in version control)

Maintaining servers



Centralise your crontabs and configuration files (and put in version control)

Deploy with one script: rsync + ssh + apt-get update & apt-get upgrade (or your OS equivalent) to each server

Simplify further

Internet

Front end

Perlbal

load balancer /

proxy

Stage server

Back end

Web server

(static+dynamic)

Development

server (in the

office)

Database

server

Back end

Web server

(static+dynamic)

Cache

Simplify further

Internet

Front end

Perlbal

load balancer /

proxy

Stage server

Back end

Web server

(static+dynamic)

Development

server (in the

office)

Database

server

Back end

Web server

(static+dynamic)

Cache

Simplify further

Internet

Front end

Perlbal

load balancer /

proxy

Stage server

Back end

Web server

(static+dynamic)

Development

server (in the

office)

Database

server

Back end

Web server

(static+dynamic)

Cache

Waiters: cheaper, faster and less demanding


InternetKids


InternetKids

Front endWaiters - good at serving quickly and dealing with annoying customers or

Kitchens



Chefs - simple and complex meals(static and dynamic)

Kitchen 1

Kitchen 2


Kitchens



Chefs - simple and complex meals(static and dynamic)

Kitchen 1

Kitchen 2

CacheFreezer


Kitchens

More tips for faster user experience

mod_gzip

mod_gzip

HTML/css/xml

mod_gzip

HTML/css/xml

mod_gzip

HTML/css/xml gzip

mod_gzip

HTML/css/xml gzip

mod_gzip

HTML/css/xml gzip Users

mod_gzip

HTML/css/xml gzip

If a browser support compressions... compress(javascript can be tricky - at least minify)

Users

Cache headers (expiry)



Let web browsers know how long to cache

Cache somethings forever


/includes/js/<VERSION>/common.js


Ensures user has version which matches HTML (client could have cache of old HTML)



Ensures user has version which matches HTML (client could have cache of old HTML)

Use include file to update all pages


Handling images: MogileFS


Store images by group (replication levels)



Spread IO across disks & servers




Retrieve from fastest server





Integrate with Perlbal, hidden from the user






Automatic resilience






Automatic resilience

Basic rules to consider


Centralise (code/templates/configuration/deployment etc)



Test, run lots of them




Cache if you need it; memcache is great





Keep is simple (perlbal especially)





Keep is simple (perlbal especially)

Sometimes it's just easier to buy another server (this is not always true)

We covered...

We covered...

perlbal

We covered...

perlbal

memcached

We covered...

perlbal

memcached

svk (subversion)

We covered...

perlbal

memcached

svk (subversion)

trac

We covered...

perlbal

memcached

svk (subversion)

trac

rsync

We covered...

perlbal

memcached

svk (subversion)

trac

rsync

gzip

We covered...

perlbal

memcached

svk (subversion)

trac

rsync

gzip

mogileFS

We covered...

perlbal

memcached

svk (subversion)

trac

rsync

gzip

mogileFS

server architecture

We covered...

perlbal

memcached

svk (subversion)

trac

rsync

gzip

mogileFS

server architecture

Test::More

We covered...

perlbal

memcached

svk (subversion)

trac

rsync

gzip

mogileFS

server architecture

Test::More

mod_perl

We covered...

perlbal

memcached

svk (subversion)

trac

rsync

gzip

mogileFS

server architecture

Test::More

mod_perl

Template::Toolkit

We covered...

perlbal

memcached

svk (subversion)

trac

rsync

gzip

mogileFS

server architecture

Test::More

mod_perl

Template::Toolkit

HTTP Cache headers

We covered...

perlbal

memcached

svk (subversion)

trac

rsync

gzip

mogileFS

server architecture

Test::More

mod_perl

Template::Toolkit

HTTP Cache headers

and...

...how a kitchen should run



Any questions?

Evolving architecturehttp://leo.cuckoo.org/projects/ea/

Leo Lapworthhttp://leo.cuckoo.org/

http://leo.cuckoo.org/projects/ea/

http://leo.cuckoo.org/projects/ea/



Technology

Evolving Archetecture