12 core technologies you should learn , love , and hate to be a 'real' technocrat jon linowes podcamp nh nov 8, 2009
12 core technologies you should learn, love, and hate to be a 'real' technocrat
Jun 20, 2015
podcamp nh nov 8, 2009
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
12 core technologies you should learn, love, and hate to be a 'real' technocrat
jon linowespodcamp nh nov 8, 2009
what?why?
learn
knowledgeskillfulove
appreciationpassionftw
hate
confusionpainwtf
oscillating between confusion and success, as one progresses along a learning curve
-1, 0, +1where are you?
1. the command line
2. html (tags, dom)
3. css (styles, selectors, media type)
4. http (request, response, caching, sessions)
5. programming (objects, control, BDD)
6. javascript (& ajax)
7. MVC application frameworks
8. database (structure, sql)
9. hosting (server layers, clusters, caching)
10. media - images, video & mp3 (resolution, compression, etc)
11. business (users, customers, partners, investors, staff)
12. (TBD)
TIME CHALLENGE
Time allotted: 45 minutes
Presentation: 35 minutes
Discussion: 10 minutes
75 slides = 28 seconds per slide...
1. the command line
Command Line, Why?
because it feels good to “let your fingers do the walking”while you're working “under the hood”
it can be...faster (typing vs clicking)more direct (names vs picture)more flexible (plethora of options)you're already there (fingers already on the kb)more natural (login to remote machines)the only way (e.g ping)
Example *nix commands:
ls -lSr - list files (sorted by size)less some.file - list a text document, paginatemkdir newfolder - create a new folder (directory)mv my.file newname.file - move, rename a filecp my.file dup.file - copy a filescp my.file [email protected]:/stuff - copy a file across the 'netdu -sh /some/dir - show how much space dir is taking upps aux | grep blah - list all the running processes
but only show ones that contain 'blah'mysqldump > mydb.sql - backup a databasemysql < mydb.sql - restore a databasewget -spider http://0at.org - fetch pages and behave like a web spider:
don't download, just check to see if there
2. html
html: structure
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head> <title>Corporate Information - Company Overview</title> </head>
<body>
<div id="container">
<h2>Company Overview</h2>
<p> <strong>Our name</strong> </p>
<p>Founders Larry Page and Sergey Brin named the search engine they built "Google," a play on the word "googol" </p>
</div>
</body>
</html>
Source: http://www.w3schools.com/tags/tag_DIV.asp
html: tags
Firefox Firebug plugin
and Web Developer plugin
Safari Web Inspector
DOM
html: DOM● the Document Object Model (DOM) is an application programming interface
(API) for valid HTML and well-formed XML documents.
● the term "document" is used in the broad sense (increasingly, XML is being
used as a way of representing many different kinds of information)
● programmers can build documents, navigate their structure, and add, modify,
or delete elements and content.
Source: http://www.w3.org/TR/DOM-Level-2-Core/introduction.html
3. css
“Cascading Style Sheets”
cascade |kasˈkād|a process whereby something, typically information or knowledge, is successively passed on” (Oxford)
The cascade:
● browser defaults
● CSS file(s)
● <style> tag in HTML
● style= attribute in a tag
Un-styled document, has content and structure
html + css = formatted content
“Themes” are standard styles applied to a standard document structure
(Themes may also extend the document structure using templates)
css:selectors
Source: http://www.w3.org/TR/css3-selectors/
css:media types
4. HTTP
A Web browser is a software application for retrieving, presenting, and
traversing information resources on the World Wide Web.
An information resource is identifi ed by a Uniform Resource Identifi er
(URI) and may be a web page, image, video, or other piece of content.
Hyperlinks present in resources enable users to easily navigate their
browsers to related resources.
Source: http://en.wikipedia.org/wiki/Web_browser
ping request
[22:24][jonathan@jsl:~]$ ping google.comPING google.com (74.125.45.100): 56 data bytes64 bytes from 74.125.45.100: icmp_seq=0 ttl=50 time=759.847 ms64 bytes from 74.125.45.100: icmp_seq=1 ttl=50 time=800.581 ms64 bytes from 74.125.45.100: icmp_seq=2 ttl=50 time=729.355 ms
p.s. satellite internet sucks esp during peak times
- ping looks up domain name in DNS, gets IP address- ping sends “echo” request with a “payload” (data) to the IP address- server listening, accepts the request, echo's back the data- ping receives echo, verifies, and prints time it took for round-trip
First, let's consider a “ping”:
Useful to verify server is alive, and measure response times (your ISP + Internet in general + that specific server, combined).
browser:http request
Example: http://www.google.com
- browser looks up domain name in DNS, gets IP address- browser sends HTTP GET request to the IP address- server listening on port 80, accepts the request- server prepares a response- server sends response back to browser (status: 200 ok)- browser receives response, parses the document- browser may GET additional stuff (images, css, etc)- browser builds the DOM, and paints the screen
http response
Response Headers - http://www.reviewramp.com/
Date: Thu, 05 Nov 2009 05:04:53 GMTServer: Mongrel 1.1.1Status: 200Etag: "baf1a682b9b690de2b1e5ff15be8193d"X-Runtime: 8Cache-Control: private, max-age=0, must-revalidateContent-Type: text/html; charset=utf-8Content-Length: 9329Connection: Keep-AliveKeep-Alive: timeout=3Set-Cookie: _reviewramp_session_id=BAh7BzoPc2Vzc2lvbl9pZCIlYWU...
200 OK
Example HTTP response header:
Status: response code
eTag: for cache
Content-type: kind of data, for browser
Set-cookie: cookies, for server
1xx Informational
2xx Success200 OK
3xx Redirection301 Moved Permanently302 Found – this is the most popular redirect code304 Not Modified – use the cache
4xx Client Error403 Forbidden – the request was a legal request, but server is refusing to respond to it404 Not Found
5xx Server Error500 Internal Server Error
httpresponse codes
Conditional GETs
Conditional GETs based on dateHTTP header has Last-Updated. If you store this with a copy of the data, you can avoid re-
fetching it if it hasn't changed. When you next make a request, include this date in the header If-
Modified-Since. If the data has not changed, Gliffy will respond with an HTTP status of 304,
indicating you may safely use your cached copy.
Conditional GETs based on entity tag (eTag)An alternate means is to use an "entity tag", which is essentially a hash of the data. Certain
resources will include an HTTP header for ETag. Save this value with the data. When you re-
request the data, include the header If-None-Match and use the value of the ETag you stored in
the cache. If the data to serve you has not changed, it will have the same ETag, and will return an
HTTP status of 304, indicating you may safely use your cached copy.
browser cache
Source: http://www.gliffy.com/developer/apidocs/rest/
browser session
The web is inherently “stateless”Each request is self contained and must have all the infoneeded to complete the transaction.
A cookie is a 'chunk' of data stored in the browser which is passed along to the server on each request.
A session cookie contains a unique identifier so the server knows who the request came from (eg after you logged in)
Source: http://www.jeevanchaaya.com/2008/10/14/web-application-state/
5. programming
programming:objects
– a self-contained thing with an interface (API) to create, modify, control, destroy, etc.
– once defined (programmed), others can use it (other objects, other programmers)
– has its own data
– as long as the API stays the same, the internal implementation can change (“refactor”)
Class versus Instance
“car” - class of object
“my car” - an instance of “car”
programming:control flow
def wipe_mutterings_from( sentence )
unless sentence.respond_to? :include?
raise ArgumentError,
"cannot wipe mutterings from a #{ sentence.class }"
end
while sentence.include? '('
open = sentence.index( '(' )
close = sentence.index( ')', open )
sentence[open..close] = '' if close
end
end
programming: Ruby examples
non_eggroll = 0
kitty_toys.each do |toy|
next if toy[:shape] == 'eggroll'
non_eggroll = non_eggroll + 1
end
def grant( wish )
if wish.length > 10 or wish.include? ' '
raise ArgumentError, "Bad wish."
end
if @energy.zero?
raise Exception, "No energy left."
end
@energy -= 1
Endertromb::make( wish )
end
source: http://mislav.uniqpath.com/poignant-guide/book/chapter-1.html
File: page_spec.rb
describe Page, "name" do it "should convert spaces and illegal chars to underscore" do p = new_page( :name => "a b@c$d-e&f?g") p.should be_valid p.name.should == "a_b_c_d_e_f_g" endend
Behavior specification:
File: page.rb
class Page < ActiveRecord::Base require "string"
def before_validation self.name = name.urlize if name endend
Class definition:
File: string.rb
class String def urlize self.strip.downcase.gsub(/[^\w\.]+/, '_') endend
programming: behavior-driven
Module:
6. javascript
- client-side (browser) programming language
- used to be “bad” (problems: cross browser, security, accessibility, usability)
- Google legitimized Javascript (gmail, earth etc). Libraries like jQuery solve browser and usability issues.
- integrated into all browsers, has built-in DOM support
- use the <script> tag to embed into HTML
- used for making “smarter” web pages, visual effects, better GUI, AJAX, client-side applications
Other client-side programming:- VBscript- ActiveX- Flash
image: http://www.somethingdigital.co.za/services.php
javascript:example
<div> <script type="text/javascript">todays_date()</script></div>
function todays_date() {
var now = new Date();
var days = new Array( 'Sunday' ,'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday');
var months = new Array( 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December');
var date = now.getDate();
var today = days[now.getDay()] + ", " + months[now.getMonth()] + " " + date + ", " +(fourdigits(now.getYear()));
document.write(today)}
function fourdigits(number){ return (number < 1000) ? number + 1900 : number;}
Wednesday, November 4, 2009
javascript:jQuery example
$(document).ready(function() { $('#faq').find('dd').hide().end().find('dt').click(function() { $(this).next().slideToggle(); }); });
source: http://docs.jquery.com/Tutorials:Getting_Started_with_jQuery
- wait 'till document is loaded into the browser- select element with ID=”faq” (presumably a DIV)- find all <dd> elements within that element (presumably the answer text), and hide them- find all <dt> elements within '#faq' (presumably the question text), and when one is clicked:
- find the next element (presumably the <dd> tag>- and show it by sliding down to reveal- (or if presently visible, hide it by sliding up to hide)
Think of a FAQ page, where all answers are hidden first, and shown when the question is clicked. The jQuery code for this:
ajax
ajax
source: http://www.adaptivepath.com/images/publications/essays/ajax-fig1.png
7. MVC application frameworks
source: http://www.bhartisoftland.com/technologies-skill-sets/gifs/mvc-php.png
REST“Representable State Transfer” … whatever.
REST describes an architecture paradigm for web applications
that request and manipulate web resources using the standard
HTTP methods GET, POST, PUT and DELETE.
source: http://topfunky.com/clients/peepcode/REST-cheatsheet.pdf
ref: http://www.b-simple.de/download/restful_rails_en.pdf
<h1>Public Directory</h1>
<% if @public_projects.empty? %>
<h3>No public projects found on this account</h3>
<% else %>
<div id="projects_list">
<%= render :partial => "project", :collection => @public_projects %>
</div>
<% end %>
View: templates
source: http://www.adobe.com/newsletters/edge/october2008/articles/article2/index.html?trackingid=DWZST
Model: ORM“object-relational mapping”maps a database table to an object in the frameworke.g. Rails' ActiveRecord
Model: associations
source: http://guides.rails.info/association_basics.html
8. database
Application => SQLUser.find 3090 SELECT * FROM `users` WHERE (`users`.`id` = 3090) LIMIT 1
@account.projects.find_by_name “test” SELECT * FROM `projects` WHERE (`projects`.`name` = 'test') AND ((`projects`.account_id = 800)
Account.create :name => “newco” INSERT INTO `accounts` (`name`, `created_at`, `updated_at`, `deleted_at`, `owner_id`) VALUES('newco', '2009-11-04 08:21:30', '2009-11-04 08:21:30', NULL, NULL)
SQL
database performance
Database management has a long, hard, cold history dating back decades, housed in the faux floored realm of corporate IT departments and enterprise software co's like Oracle and SAP.
And then there were “toy” databases on PC's for personal and small business.
The massive proliferation of websites, web servers, and web applications since the 1990's has pulled database technology into the hands of unwitting and often clueless people like you and me. But we are learning.
Usually, small and simple is good enough. But sometimes you -really- need to scale. Personally, I haven't, yet.
As a developer, do the basics to optimize database performance: index the tables, perform benchmarks, watch the logs, tune the app, use the expert services at your hosting company, perform regular maintenance, and, of course, backup.
As a user, stand in awe of the likes of Google, Facebook, CNN, and the iTunes store.
BUT, IT'S NOT JUST THE DATABASE, stupid...
9. hosting
Example: Engine Yard
source: http://www.engineyard.com/technology
Disclaimer: I am neither a customer nor employee of Engine Yard or Heroku, but I've looked at them because they specialize in Rails hosting. More important, I like their graphics.
10. media
source: http://kindacarsick.com/post/230881676#
resolution
Image Video Audio
resolution width (pixels)height (pixels)depth (#colors,
or bits RBG)
width (pixels)height (pixels)length (time)frames rate (fps)
channels (mono/stereo)bit rate (kbps)
compression(for example)
jpg H.264 mp3
Resolution defines the physical dimensions, attributes of the data.
Reducing the resolution means sampling the data.
Compression can be loss-ey, or loss-less which files are much larger.
source: http://www.wavetrace.com/images/RatesAndResolution.gif
Relationship between resolution and sampling
source: http://www.stereophile.com/features/308mp3cd/
Pixellation is sampling (and/or averaging) and then re-enlarging(generally not a good idea)
http://www.umt.edu/geosciences/faculty/sheriff/438-Gravity_Electromagnetics/images/Anomaly%20sampling.gif
Sampling at too low a resolution can loose significant features
CD tones: After MP3 compression:
Compression also introduces noise
11. business business == people
ok, so it's not really a technology, but it is the context
I LOVE MY USERS
I HATE MY USERS
I LOVE MY CUSTOMERS
I HATE MY CUSTOMERS
I LOVE MY PARTNERS
I HATE MY PARTNERS
I LOVE MY STAFF
I HATE MY STAFF
12. [TBD]
What's your love, appreciation, passion?
What's your hate, confusion, pain?
What do you want to learn, know, be skilled?
Where are you between WTF and FTW?
Jon Linowes
[email protected] twitter @linojon
my main project: http://reviewramp.com “Submit... Review... Decide!”
technical blog: http://vaporbase.com personal blog: http://jon.linow.es
Related Documents
