Evolving Archetecture

Evolving architecturemake development easy and your site faster

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

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...

Covering anything in depth

Concepts stolen from

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>";

How about...

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

and...

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

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

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

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...

Version control & docs

Use SVK with Subversion

Clkao - SVK

Use Trac (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

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

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

Internet

Front end

Web server

(static & proxy to

application server)

Development

server

Back end

(application server)

Web server

(dynamic)

Database server

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

Internet

Front end

Web server

(static & proxy to

application server)

Development

server

Back end

Web server

(dynamic)

Database server

Speed up the frequent...

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

Speed up the frequent...

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

Can this information persist for a period of time?

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

Look-ups of information from a database

Individual items

Look-ups of information from a database

Fetching of information from external sources

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

We now have a cache

Internet

Front end

Web server

(static & proxy to

application server)

Development

server

Back end

Web server

(dynamic)

Database server

CacheCache

Adding in the cache...

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)

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)

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

Second kitchen, two freezers...

InternetKids

Back endChefs

Kitchen 1

Kitchen 2

InternetKids

Back endChefs

Kitchen 1

Kitchen 2

CacheFreezers

We want a cache across servers...

EnterMemcache

We want a cache across servers...

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)

Shared freezer

InternetKids

Shared freezer

InternetKids

Shared freezer

InternetKids Back end

Kitchen 1

Kitchen 2

Shared freezer

Kitchen 1

Kitchen 2

CacheFreezer

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 /

Stage server

Back end

Web server

(static+dynamic)

Development

server (in the

office)

Database

server

Back end

Web server

(static+dynamic)

Simplify further

Internet

Front end

Perlbal

load balancer /

Stage server

Back end

Web server

(static+dynamic)

Development

server (in the

office)

Database

server

Back end

Web server

(static+dynamic)

Simplify further

Internet

Front end

Perlbal

load balancer /

Stage server

Back end

Web server

(static+dynamic)

Development

server (in the

office)

Database

server

Back end

Web server

(static+dynamic)

Waiters: cheaper, faster and less demanding

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

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)

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)

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

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)

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

We covered...

perlbal

We covered...

perlbal

memcached

We covered...

perlbal

memcached

svk (subversion)

We covered...

perlbal

memcached

svk (subversion)

We covered...

perlbal

memcached

svk (subversion)

We covered...

perlbal

memcached

svk (subversion)

We covered...

perlbal

memcached

svk (subversion)

mogileFS

We covered...

perlbal

memcached

svk (subversion)

mogileFS

server architecture

We covered...

perlbal

memcached

svk (subversion)

mogileFS

server architecture

Test::More

We covered...

perlbal

memcached

svk (subversion)

mogileFS

server architecture

Test::More

mod_perl

We covered...

perlbal

memcached

svk (subversion)

mogileFS

server architecture

Test::More

mod_perl

Template::Toolkit

We covered...

perlbal

memcached

svk (subversion)

mogileFS

server architecture

Test::More

mod_perl

Template::Toolkit

HTTP Cache headers

We covered...

perlbal

memcached

svk (subversion)

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/

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