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Modern Web Technologies (and why
you should care)Reuven M. Lerner • [email protected]
MegacommFebruary 15th, 2012
Who am I?
• Web developer since 1993
• Software architect/consultant/trainer
• Linux Journal columnist since 1996
• Mostly Ruby on Rails + PostgreSQL, but also Python, jQuery, MySQL, and more...
• PhD candidate at Northwestern University
How does the Internet (TCP/IP) work?
Client Server“Socket”
Port Port
How does the Internet (TCP/IP) work?
Client Server“Socket”
Client opens connection
Port Port
How does the Internet (TCP/IP) work?
Client Server“Socket”
Client opens connection
Port Port
Server accepts connection
Protocols
• Communication standards built on top of TCP/IP, typically text-based
• SMTP (e-mail)
• FTP (file transfer)
• NNTP (transfer of “news” articles)
WWW:Three technologies
• Markup format: HTML
• URL: protocol + server + port + doc
• Protocol: HTTP
How the Web works
Browser Server
How the Web works
Browser Server
HTTP Request
How the Web works
Browser Server
HTTP Request
HTTP Response
How the Web works
Browser Server
HTTP Request
HTTP Response
Stateless — after the response is sent, the connection is broken and forgotten
Simple request
Browser Server
Simple request
Browser Server
GET /
Simple request
Browser Server
GET /
200 OK<html><head>...</head><body>...</body></html>
Not found?
Browser Server
Not found?
Browser Server
GET /blahblah
Not found?
Browser Server
GET /blahblah
404 Not found
Three things are certain:
Death, taxes, and lost data.
Guess which has occurred.
— David Dixon, Salon magazine contest
Submitting forms
Browser Server
Submitting forms
Browser Server
POST /loginname=reuven&password=secret
Submitting forms
Browser Server
POST /loginname=reuven&password=secret
200 OK<html>...<p>Thank you!</p>...</html>
Document = request
• If an HTML page contains images, then each is retrieved in a separate HTTP request
• Page with 30 images = 31 HTTP requests
• Page with 20 images, 10 JavaScript files, and 5 CSS files = 36 HTTP requests
Idea: Lie to the browser
• Don’t return a document to the user
• Rather, run a program when the user makes a request, and send the program’s output
• If the output is in HTML, then the browser will show it no differently than a static doc
Just in time production
• Wait as long as possible to create pages for the user
• Ideally, create them when the user requests them
• “Mass customization”
Dynamic document
Browser Server
Dynamic document
Browser Server
GET /
Dynamic document
Browser Server
GET /
200 OK<html><head>...</head><body>...</body></html>
Dynamic document
Browser Server
GET /
200 OK<html><head>...</head><body>...</body></html>
Program output
What we return
• Usually HTML
• Image (e.g., stock graphs, Google Analytics)
• Word/Excel doc (e.g., from Google docs)
• PDF (e.g., PDF reports)
• XML, JSON (for computers, not people)
• Basically, any defined MIME type
APIs and mobile apps
Computer B (server)
Computer A (browser)
APIs and mobile apps
Computer B (server)
GET /
Computer A (browser)
APIs and mobile apps
Computer B (server)
GET /
200 OK<some-xml><talk>JWP</talk></some-xml>
Computer A (browser)
APIs and mobile apps
Computer B (server)
GET /
200 OK<some-xml><talk>JWP</talk></some-xml>
APIs and mobile apps
Computer B (server)
GET /
200 OK<some-xml><talk>JWP</talk></some-xml>
APIs and mobile apps
Computer B (server)
GET /
200 OK<some-xml><talk>JWP</talk></some-xml>
APIs and mobile apps
Computer B (server)
GET /
200 OK<some-xml><talk>JWP</talk></some-xml>
What is a Web app?
• Receives its inputs via HTTP
• Sends its output via HTTP
• That’s it! A Web application can do anything you want, within these limits
That’s it!
• Now you understand how the Web works.
• Really, that’s it.
• Go home.
OK, perhaps not...
• How do we write these programs?
• Where (and how) do we store user data?
• How have the underlying technologies (URLs, HTTP, and HTML) advanced?
Early Web applications
• First server-side programs were in C
• They were compiled into binaries
• So you had the CGI source (cgi-src) directory...
• ... and the CGI binary (cgi-bin) directory
• No explicit compilation
• Cross platform
• Built-in, powerful text functions
• Do a lot in a little bit of code
• Perl, Python, PHP, Ruby
• Typically open source
“Scripting” languages
Frameworks
• DRY (Don’t repeat yourself)
• Get rid of the drudgery
• Concentrate on your business, rather than worrying about common Web issues
MVC paradigm
• Most modern frameworks use MVC
• From Smalltalk in the 1980s!
• Model — communicates with database
• View — HTML/JavaScript/CSS for user
• Controller — handles requests
• Clear division of labor
Web frameworks in dynamic languages
• Programmer speed trumps execution speed
• Community support
• Plugins for commonly requested features
• Create a domain-specific language (DSL) for your specific needs
Ruby on Rails
• Ruby language
• Rails Web app framework (MVC)
• Designed for writing Web DSLs
• “Convention over configuration”
• Thousands of little improvements
• ActiveRecord — ORM
Person model
class Person < ActiveRecord::Base
end
Where’s the definition?
• The computer takes care of it automatically
• ActiveRecord knows what columns you have defined, and what their types are
• (More on columns later)
• Only write things that cannot be understood automatically
Not only Rails
• Python (Django)
• PHP (Symfony)
• Perl (Catalyst)
• Groovy (Grails)
• Even if you don’t use Ruby on Rails, you have benefitted from its “opinions”
Plugins
• Rails (and other systems) have open-source plugins to handle common issues
• Authentication
• E-commerce
• Social networking
• Don’t write these yourself! Customize existing code that has proved itself
Storage
• Applications are great!
• But what if we want to store information about our users?
• Name, e-mail address, account balance
• We could use text files, but most people will use a database
What is a database?
Database
Store data confidently
Retrieve data flexibly
Relational databases
Define tables, store data in them
Database
Retrieve data from related tables
Relational database
SQL goes hereCREATE TABLE
INSERTUPDATEDELETE
Database
Relational databases
• Everything is stored in 2-dimensional tables
• Data should appear only once (normalized)
• “Join” tables to connect tables
• Technology is extremely robust, fail-safe
• Not all data is a good fit for this paradigm
id first_name last_name phone
1 Reuven Lerner 054-496-8405
2 Charlie Kalech 02-671-9918
id first_name last_name email
1 Reuven Lerner [email protected]
2 Charlie Kalech [email protected]
person_id phone_number
1 054-496-8405
1 847-230-9795
2 02-671-9918
2 054-803-3356
2 501-629-8620
id first_name last_name email
1 Reuven Lerner [email protected]
2 Charlie Kalech [email protected]
id type
1 work
2 mobile
3 fax
4 home
person_id phone_number_type_id phone_number
1 2 054-496-8405
1 1 847-230-9795
2 1 02-671-9918
2 2 054-803-3356
2 3 501-629-8620
id first_name last_name email
1 Reuven Lerner [email protected]
2 Charlie Kalech [email protected]
id type
1 work
2 mobile
3 fax
4 home
person_id phone_number_type_id phone_number
1 2 054-496-8405
1 1 847-230-9795
2 1 02-671-9918
2 2 054-803-3356
2 3 501-629-8620
SELECT P.first_name, P.last_name, P.email, PN.phone_number, PNT.typeFROM People P, Phone_Numbers PN, Phone_Number_Types PNTWHERE PN.person_id = P.id AND PNT.id = PN.phone_number_type_id
Another language!
• SQL is the language of relational databases
• So a Web app will use a language (e.g., Ruby, Python, or PHP) + SQL
• Or use an ORM, which automatically translates your language into SQL
Person.first.phone_number
Extending our diagram
Browser
Extending our diagram
Browser
HTTP Request
Extending our diagram
Browser Server
HTTP Request
Extending our diagram
Browser Server
HTTP Request
Extending our diagram
Browser Server
HTTP Request
Database
Extending our diagram
Browser Server
HTTP Request
Database
Extending our diagram
Browser Server
HTTP Request
HTTP Response
Database
Popular databases
• PostgreSQL (my favorite)
• MySQL
• Microsoft SQL Server
• Oracle
• Most popular: SQLite!
Scaling problems
• Lots of requests?
• Optimize
Scaling problems
• Lots of requests?
• Optimize
• Even more requests?
• Buy a bigger server
Scaling problems
• Lots of requests?
• Optimize
• Even more requests?
• Buy a bigger server
• What next?
• Panic! (Or spend lots of money)
Sharding
• Split your data across multiple databases
• This works, but...
• Requires rewriting a lot of code
• Maintenance is a big issue
• Re-sharding as each server gets overwhelmed can be expensive, time-consuming
Non-relational databases
• Don’t store things in tables!
• Don’t pre-define a schema
• No SQL!
• Indeed, known as “NoSQL” databases
• Only common factor: No SQL, non-relational
Examples
• Key-value stores
• e.g., Memcached, Redis, Tokyo Cabinet
• Columnar databases
• e.g., Cassandra
• Document databases
• e.g., MongoDB, CouchDB
MapReduce / Hadoop
• Google and Yahoo do it like this:
• Split data across many servers
• Run a function on all of those servers
• Collect the results
• Display to the user!
• (Too slow? Add more servers!)
NoSQL: Good news
• Often easier to administer, configure
• Scaling to multiple servers is a no-brainer
• No new programming language (SQL)!
• Better fit for certain kinds of data
• Better performance than a relational DB
• Lots of options to choose from!
NoSQL: Bad news
• Speed is in the eye of the beholder
• Is “eventually consistent” good enough?
• Non-normalized data — ugh!
• Reporting can be harder
• Less tested than relational databases
• Can you trust your data to them?
Meanwhile...
• Our browsers are displaying HTML
• HTML had several problems:
• Standardized set of tags
• Making it easy for programs to parse
• Semantic, display content were mixed
HTML standards
• HTML — several versions, several standards, none universally accepted
• XML — lets us create HTML-like languages, for computer conversations
• XHTML — HTML for pedantic people
• It was a big mess!
HTML5
• Relaxes much of the formality of XHTML, while remaining easy for computers to read
• Backward compatible to a large degree
• Adds a number of tags for better semantics
• Best of all: Lots of new JavaScript goodies
• More on this in a moment
HTML5 declaration
HTML5 declaration
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
HTML5 declaration
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<!DOCTYPE html>
New “email” tag
<input type=”text” name=”email” />
<input type=”email” name=”email” />
New “url” tag
<input type=”text” name=”url” />
<input type=”url” name=”url” />
New “date” tag
<input type=”date” name=”date” />
Color picker!
<input type=”color” name=”color” />
And more
• Validation — built-in validation of form element inputs, via regular expressions
• No more JavaScript plugins!
• Sliders — more natural numeric inputs
• Canvas — draw any picture you might like, and detect/change it with software
• Hints in text fields (e.g., “search”)
My favorite
• Private data in attributes!
• Any attribute starting with “data-” is considered valid
• A great way to stash information inside of HTML elements without violating standards
Oh, yeah
• These don’t all work.
• Many of them don’t work on any browser
• Most work on only some browsers.
• What to do? Wait. Or use Modernizr, which uses JavaScript to detect features.
• If a feature isn’t there, you can fall back
CSS
• Cascading Style Sheets
• Split semantic markup from presentation
• One CSS file can apply to an entire site
• No more “style” tags in your text!
• Easy to move place things, create effects
Ids are unique
<p id=”important”>Agenda</p>
p#important {
font-size: 13p;
font-weight: bold;
}
Classes can repeat
<p class=”important”>Agenda</p>
<p class=”important”>Lunch</p>
p.important {
font-size: 13p;
font-weight: bold;
}
It gets better
• You can set styles for when the user’s mouse hovers over or clicks on an element
• In other words: Cheap animation!
• Many uses of JavaScript (e.g., some menus) can now be done with simple CSS
• You can make beautiful sites with CSS
CSS3: Cool effects
• Rounded corners
• Transparency
• Text shadows and drop shadows
• Gradients
CSS3: Cool selectors
• If you love regular expressions, then these selectors will be second nature to you:
p[id=”foo”] { background: green}
p[id^=”foo”] { background: green}
p[id$=”foo”] { background: green}
p[id*=”foo”] { background: green}
CSS3: Cool selectors
• If you love regular expressions, then these selectors will be second nature to you:
p[id=”foo”] { background: green}
p[id^=”foo”] { background: green}
p[id$=”foo”] { background: green}
p[id*=”foo”] { background: green}
Equals
CSS3: Cool selectors
• If you love regular expressions, then these selectors will be second nature to you:
p[id=”foo”] { background: green}
p[id^=”foo”] { background: green}
p[id$=”foo”] { background: green}
p[id*=”foo”] { background: green}
Starts with
CSS3: Cool selectors
• If you love regular expressions, then these selectors will be second nature to you:
p[id=”foo”] { background: green}
p[id^=”foo”] { background: green}
p[id$=”foo”] { background: green}
p[id*=”foo”] { background: green}
Ends with
CSS3: Cool selectors
• If you love regular expressions, then these selectors will be second nature to you:
p[id=”foo”] { background: green}
p[id^=”foo”] { background: green}
p[id$=”foo”] { background: green}
p[id*=”foo”] { background: green}Contains
OK, that’s nice.
• But really, the big news with HTML5 doesn’t have to do with HTML at all.
• Instead, it has to do with JavaScript.
• Remember JavaScript?
• It’s the programming language that we love to hate. (At least, I used to.)
JavaScript
• Originally “LiveScript,” a language that executes programs in the browser
• Renamed “JavaScript” when an unrelated language (“Java”) stole the thunder
• Renamed (officially) ECMAScript for standardization purposes
• No one actually calls it this
HTML5 turns the browser into a smart, powerful, networked application platform.JavaScript makes it
possible.
Powerful? Huh?
• Didn’t I just say that I love to hate JavaScript?
• And then I said that it was powerful?
• What gives?
JavaScript isthe new hotness
• Browsers are competing for fastest, best
• Google’s V8
• Mozilla’s TraceMonkey (and JägerMonkey)
• Safari’s Nitro
• IE’s Chakra
• JavaScript is faster, more stable than ever!
Server-side JavaScript!
• The latest JavaScript development
• Run it on your server!
• Why? Because it’s super-fast
Also: frameworks
• Remove the drudgery of JavaScript
• Handle differences between browsers
• Make it easy to perform common tasks
• Lots of plugins available
• For me, it’s the difference between pain and pleasure when working with JavaScript
JavaScript frameworks
• Dojo
• YUI
• MooTools
• Prototype
• jQuery (the 900-pound gorilla)
jQuery
• jQuery has taken the world by storm
• Super-easy to use
• Extremely fast
• Open source (of course!)
• Easy to write plugins
• Lots of plugins are available
Ajax
• One reason for JavaScript libraries: Ajax!
• Make HTTP requests from within the page
• No refresh! Just get results from the server, and modify the page accordingly
• This has revolutionized our view of Web pages
Ajax
Browser Server
Ajax
Browser Server
POST /loginname=reuven&password=secret
Ajax
Browser Server
POST /loginname=reuven&password=secret
200 OK<html>...<p>Thank you!</p>...</html>
Ajax
Browser Server
POST /loginname=reuven&password=secret
200 OK<html>...<p>Thank you!</p>...</html>
Ajax
Browser Server
POST /loginname=reuven&password=secret
200 OK<html>...<p>Thank you!</p>...</html>
Ajax
Browser Server
POST /loginname=reuven&password=secret
200 OK<html>...<p>Thank you!</p>...</html>
Ajax
Browser Server
POST /loginname=reuven&password=secret
200 OK<html>...<p>Thank you!</p>...</html>
Ajax isn’t everything
• What if I want a chat application, or something else that stays open?
• What if I want to execute more than one JavaScript function at a time?
• What if I want to store things locally?
• HTML5 provides all this — and more!
Canvas
• A complete drawing area, in your browser!
• Use JavaScript to:
• Draw arbitrary shapes
• Detect the mouse
• Detect the drawing
• The end of Flash? Maybe...
Geolocation
• Your browser can know where you are!
• It can send this info to the server
• It’s not perfect, but still pretty good
• To avoid privacy issues, users are always asked if their location should be shared
Inter-page communication
• Modern Web apps can span multiple pages
• HTML5 makes it easy for two pages (from the same server) to communicate
• The receiver knows which server sent the data — so it can filter incoming messages, as well as screen them for security
Web sockets
• This is potentially the biggest deal of all
• Ajax allows for server connections. But:
• High overhead
• Stateless
• Web sockets have low overhead, and they stay open as long as you need!
Using Web sockets
Using Web socketsvar weatherSocket = new WebSocket("ws://localhost:8080");
Using Web socketsvar weatherSocket = new WebSocket("ws://localhost:8080");
weatherSocket.onopen = function(e) { alert("Opened weather socket");};
Using Web socketsvar weatherSocket = new WebSocket("ws://localhost:8080");
weatherSocket.onopen = function(e) { alert("Opened weather socket");};
weatherSocket.onmessage = function(e) { alert("Got message: " + e.data);};
Using Web socketsvar weatherSocket = new WebSocket("ws://localhost:8080");
weatherSocket.onopen = function(e) { alert("Opened weather socket");};
weatherSocket.onmessage = function(e) { alert("Got message: " + e.data);};
weatherSocket.onclose = function(e) { alert("Closing socket..."); };
What can sockets do?
• Chat servers
• Stock feeds
• Teleconferencing
• Who knows?
• Remember, HTTP was only invented after sockets had been around for 15 years
Web workers
• Execute more than one thing at a time
• In other words: You can run JavaScript functions in the background
• Process text
• Open Web sockets
• Perform calculations
Local storage
• Now Web apps can store data
• A little database of name-value pairs
var foo = localStorage.getItem("bar");
localStorage.setItem("bar", foo);
Local storage
• Now Web apps can store data
• A little database of name-value pairs
var foo = localStorage.getItem("bar");
localStorage.setItem("bar", foo);
var foo = localStorage["bar"];
Local storage
• Now Web apps can store data
• A little database of name-value pairs
var foo = localStorage.getItem("bar");
localStorage.setItem("bar", foo);
var foo = localStorage["bar"];
localStorage["bar"] = foo;
Media
• Standard (well, sort of) ways to play audio and video
• No more Flash!
• Problem: No one format is supported by all browsers
Rich client-side frameworks
• Backbone
• Ember
Design frameworks
• Twitter bootstrap
• Blueprint
• Compass
Don’t forget mobile!
• iOS and Android are growing massively
• Web site vs. native app?
• (Ask Jakob Nielsen — for now, apps are better, but that won’t last for long)
• Ignore these users at your peril
Want a Web app?
• It used to be:
• “What operating system, language, and database will I use?”
• Or:
• “How can I produce an interesting Web site?”
Now it’s:
• What experience do we want to give people?
• What will they be using to access our system?
Those lead to a wide variety of questions:
• What server language and framework? JavaScript framework? Hosted or cloud?
• What type of database (relational, NoSQL)? Which one? Hosted or cloud?
• Do we offer an API? A mobile app? Both?
• Which HTML5 features do we want to use, and how do we gracefully degrade?
The key takeaway
• Web sites are far more than just static text, blogs, or forums
• They’re full-fledged software applications
• Take advantage of these technologies, and you can create a fabulous experience
• (Don’t take advantage of them, and your competitors will!)
Oh, yeah: Testing
• Automated testing is amazing
• Your Web site should use it
• Most modern frameworks support some sort of testing — if not, change framework
• Catch dumb bugs and issues before your customers do!
• Faster and cheaper than people
My brain is too small!
• Yes, there’s a lot to learn
• Most of it can wait a little bit
• There are oodles of tutorials and books that can help you
• Besides a lot of this is still highly transitional
Whew!
• There’s a lot to the modern Web
• It’s fun and exciting, and continues to move forward at breakneck speed
• Understanding as many of these parts as possible will help you make better decisions, and better applications!
Any questions?
• Call me: 054-496-8405
• E-mail me: [email protected]
• Interrupt me: reuvenlerner (Skype/AIM)