Document 7328277

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Transcript Document 7328277 

So Many Tools, So Little Time
Architecture of
Present and Future
Web Technologies
Version 2.0
Jay Sissom
Indiana University
[email protected]
Agenda
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Basics
Example application
Tool overview
DHTML/XML
Summary
•Perl/CGI
•Perl Apache Module
•PHP 3
•Cold Fusion
•Active Server Pages
•VB Webclasses
•Java Server Pages
•Java Servlets
•Enhydra Java App Server
Disclaimers and
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Fine Print
Jay likes compiled languages much
better than interpreted
Jay likes strongly typed languages
Jay has LOTS of opinions
What’s right for Jay might not be right
for you
Examples don’t contain all the error
checking they should!
Web Transaction
Client
http://webdev.indiana.edu/cgi-bin/AcctBal
Server
webdev.indiana.edu
Web Transaction
Connect to webdev.indiana.edu
Hello client, how
may I serve you?
GET /cgi-bin/AcctBal
I’m going to run this program
/www/cgi-bin/AcctBal, then
send you it’s output
Client
Server
Thanks, Bye!
Bye!
http://webdev.indiana.edu/cgi-bin/AcctBal
webdev.indiana.edu
Example program
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IU departmental surplus auction site
Modeled after eBay
TM
Perl/CGI
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CGI – Common Gateway Interface – the
original dynamic web content interface
Perl – Interpreted language that excels at text
processing
Perl
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One of the most used web programming
languages
Interpreted language
Weakly typed
Basic object oriented features
Available on almost any Unix and Windows 9x,
NT, 2000
Open Source
Perl Pros
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Free!
Fairly quick development
Tons of add-in modules
Lots of documentation
Has some object oriented features
Has a database abstraction layer (DBI)
Perl/CGI Cons
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JAY WARNING: Interpreted, Weakly typed
CGI has lots of overhead
Perl/CGI Resources
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http://www.perl.com/ - A bunch of Perl
resources
http://www.cpan.org/ - Perl Modules
http://www.perl.org/ - More Perl stuff
Perl Apache Web Module
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An add-on to the Apache web server
Lets you write web server modules in Perl
Perl modules are loaded/compiled when the
web server loads
Modules are reloaded when code changes (in
some cases)
Open Source
Perl Web Module Pros
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Free!
Fairly easy to learn
Code loaded and compiled once
Tons of add-in modules/databases
Lots of documentations
Has a database abstraction layer (DBI)
Perl Web Module Cons
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JAY WARNING: Interpreted, Weakly typed
You are tied to Apache
Difficult to develop/debug
Perl Web Module Resources
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http://perl.apache.org/ - Get software/docs
http://perl.apache.org/guide/ - Usage guide
http://perl.apache.org/faq/ - FAQ
http://perl.apache.org/dist/cgi_to_mod_perl.html
– Changing program from CGI – Mod Perl
PHP
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Hypertext Preprocessor
Embeds code within HTML pages
Supports many OS’s/Web Servers
Open Source
PHP Pros
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Free!
Easy to learn
Easy development
Some basic object oriented features
Supports many modules/databases
PHP Cons
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Interpreted/Weakly typed language
No database abstraction layer
PHP Templates
<?php
// code
include “whatever.template”;
?>
whatever.template
<HEAD>
<TITLE><?php echo $title; ?>
…
PHP Resources
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http://www.php.net/ - PHP offical source
http://www.phpbuilder.com/ - Example code
Cold Fusion
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Interpreted HTML preprocessor
Code is embedded in HTML pages
Specialized tags contain code
Works on NT/Solaris/Linux
Commercial Product
Cold Fusion Pros
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Commercial Support is available
A popular web development tool
Has OLEDB and native database drivers in
addition to ODBC
Cold Fusion Cons
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Interpreted language
Weakly typed language
No OO features
Cold Fusion Resources
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http://www.allaire.com/ - Allaire Corp
http://www.houseoffusion.com/ - Cold Fusion
articles/information
http://www.cfscripts.com/ - Scripts
http://www.defusion.com/ - More stuff
http://www.cfmcentral.com/ - More stuff
Active Server Pages
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HTML preprocessor
Interpreted language
Code embedded within HTML pages
NT/W2K only (3rd party package for Unix)
Only OO features come from COM
Active Server Pages Pros
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Free (comes with NT Option Pack or W2K)
Quick development
Extremely popular
Pretty good development tools
Active Server Pages Cons
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Pretty much limited to IIS on NT or W2K
COM objects must be developed in different
language
Very Weakly typed and Interpreted
Only supports ODBC & OLEDB database
interfaces
Active Server Pages Resources
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http://www.asptoday.com/ - Articles about ASP
http://msdn.microsoft.com/ - MS docs
http://www.develop.com/ - #1 MS technology
training company
VB Webclasses
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Web application development tool in Visual
Basic
Comes in the Professional & Enterprise
versions of VB
Compiled code that use HTML templates
Only runs on IIS under NT or W2K
VB Webclasses Pros
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HTML and logic are separate (kinda)
Logic is compiled!
Language is strongly typed (if you like)
Programmers write code, graphics designers
write HTML
VB Webclasses Cons
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Microsoft might drop the feature in a future
version
There are still bugs in the VB feature
Not enough separation between HTML and
logic
Webclasses & Visual Studio
SP3+ don’t work well with
Windows 2000!*
Webclasses & Win 2000
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Knowledgebase Q255502
Knowledgebase Q259725
Knowledgebase Q234317
VB Webclasses Resources
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http://msdn.microsoft.com/
http://www.asplists.com/asplists/faqvbwebclass
es.asp - FAQ
http://www.desertware.com/vbuniverse/webcla
ss.htm - Resources
Java Server Pages
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Free! (Sometimes)
The Java version of ASP & PHP
Java code embedded within HTML
Code is compiled and saved on first use
Available on many OS/Web Servers
Java is very object oriented
Java Server Pages Pros
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Code is portable
Very Strongly typed language
Code is compiled once
It’s not very difficult to port ASP to JSP
Java Server Pages Cons
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Code and HTML are in the same file
Java has a pretty steep learning curve
Java Server Pages Resources
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http://www.serverpages.com/Java_Server_Pages
http://java.sun.com/products/jsp/
Java Servlets
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Free! (usually)
Java Server API
Code is compiled and saved on first use
Available on many OS/Web Servers
Java is very object oriented
Java Servlets Pros
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API is pretty simple
Code must be compiled before using
Pretty portable
The Servlet API can be overridden to provide
additional functionality
Java Servlets Cons
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Sometimes a web server reset is required to
load changed classes
Unless you use a third party package, HTML is
in with the logic
Check out www.webmacro.org
Java Servlet Resources
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http://java.sun.com/
http://www.servletcentral.com/ - Online
magazine
http://www.servlets.com/
http://www.webmacro.org/ - Separate HTML
from code
Enhydra App Server
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Free! (pay version available)
Java based with source code
Proprietary web development model
Automatic data mapping with optional business
logic layer
Supports Servlets/Java Server Pages
Supports EJB in Enterprise edition
Available for many OS’s
Enhydra App Server
Enhydra Enterprise App Server
Enhydra App Server Pros
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Very scalable even across OS’s
Has built in data/object mapping
Proprietary interface separates HTML from code
Proprietary interface is based on WC3 DOM
Also supports Java Servlets and JavaServer
Pages
Can integrate with Jbuilder & Oracle Developer
EJB support in Enterprise edition
Enhydra App Server Cons
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Huge learning curve
Proprietary UI development is difficult
No commercial support yet
Very little documentation
Integrates with Jbuilder through Kelp add-on
Use JSP or Servlets
with their Data
Objects and
Business Objects!
Enhydra App Server Resources
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http://www.enhydra.org/
http://www.lutris.com/
Enterprise Java Beans
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A method for building business logic
EJB Servers provide support for
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Transactions
Security
Database Connectivity
Deploy EJB’s on any compatible server without
changing code*
* Assuming
you didn’t use any proprietary features of a server.
Enterprise Java Beans
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Used for very high-end applications
Supported in many servers such as:
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Enhydra Enterprise Server
JRUN
Bea Weblogic
Gemstone/J
Persistence PowerTier for EJB
IBM Websphere
Jboss Open Source Server (www.jboss.org)
And others….
Current/Future tools
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DHTML
XML
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Server side
Client side
SOAP
DHTML
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Dynamic HTML
Composed of
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–
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HTML 4.0
Cascading Style Sheets (optional)
A scripting language
Document Object Model
HTML 4.0
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Standardized by W3C Organization
Added <script> and <noscript> tags
Added support for an event model
Depreciated tags such as <font>
Cascading Style Sheets (CSS)
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Allow increased flexibility in page layout
Allows developer to separate form and content
Level 1 supported in NS 4+ and IE 4+
NS & IE support different values for the
visibility attribute making cross-browser
development more fun for us!
Scripting Languages
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Netscape developed JavaScript
Microsoft reverse engineered it and called it JScript
The ECMA standardized it and calls it
ECMAScript-262
Microsoft also supports VBScript
You can add PerlScript if you like
Warning code may be different in NS & IE and will
need to be tested/debugged in both
Document Object Model
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Standardized by the W3C
Allows access to parts of a web page
programmatically by a scripting language
<DIV> and <SPAN> tags are very important!
Uses for Dynamic HTML
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Make web pages look nicer
Allow developer to better use screen real
estate
Provide client side logic such as form validation
Dynamic HTML Examples
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Mouse overs
Transitions
Pop up menus
Drag and drop
Form validation
Dynamic HTML Resources
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Dynamic HTML by Jeff Rule (Addison Wesley)
http://www.ruleweb.com/
http://www.webreference.com/
http://www.htmlguru.com/
XML
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Extensible Markup Language
Specification developed by the W3C
A simplified version of SGML
Markup meta-language – a language for
describing markup languages
W3C is now working on rewriting HTML using
XML
XML and data
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HTML is great for describing how things should
look:
<strong>New York</strong>
– But what is this???
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XML is a way to put structured data in a text file
No presentation info – just data
We can give our data meaning
Well-formed XML
<?xml version=‘1.0’?>
<Student>
<StudentID>999-88-7777</StudentID>
<Name>Bill Smith</Name>
<Email>[email protected]</Email>
<Transfer/>
</Student>
Sharing XML
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Problem: if everyone makes up their own tags, how will
we ever agree on what the data means?
Answer: we need some rules
We need a way to define our tags, plus any
relationships between them
People who share this set of rules can exchange data
in a meaningful way
This would be valid XML
DTD
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<weather>
<city>
<name>Bloomington</name>
<report>
<high>76</high>
<low>46</low>
<precip day_total=“0” type=“rain” force=“light”/>
</report>
</city>
</weather>
Document Type Definition
<!-ELEM NAME
CONTENT MODEL
-->
<!ELEMENT
weather
(city+)
>
<!ELEMENT
city
(name, report)
>
<!ELEMENT
name
(#PCDATA)
>
<!ELEMENT
report (high, low, precip?)
>
<!ELEMENT
high
(#PCDATA)
>
<!ELEMENT
low
(#PCDATA)
>
<!ELEMENT
precip EMPTY
>
<!ATTLIST
precip
day_total
CDATA # REQUIRED
type
(rain | snow) “rain”
force (light | heavy)
#IMPLIED >
Schemas
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Schemas provide the same functionality
as DTDs, but in an XML format:
<?xml version="1.0" ?>
- <!-- Generated by XML Authority. Conforms to XML Data subset for IE 5
-->
-<Schema name="SIF" xmlns="urn:schemas-microsoft-com:xml-data"
xmlns:dt="urn:schemas-microsoft-com:datatypes">
- <ElementType name="K12Framework" content="eltOnly" order="one">
<element type="K12Register" />
</ElementType>
- <ElementType name="K12Register" content="eltOnly" order="seq">
<element type="Header" />
<element type="Source" />
</ElementType>
Schema initiatives
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There are lots of schemas already out there
Most are industry specific
No need to reinvent the wheel
Check out www.biztalk.org
Name Collisions
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What if somebody else is already using our
tags???
We need a way to allow people to define
unique tags and attributes and have them
coexist in the same document
Namespaces solve this problem
Namespaces
<x xmlns:edi='http://ecommerce.org/schema'>
<!-the 'price' element's namespace is http://ecommerce.org
/schema -->
<edi:price units='Euro'>32.18</edi:price>
</x>
XML Implementations
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Parsers
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Perl Parser based on expat found on CPAN
Xerces for for Java, Perl, C++ xml.apache.org
MSXML built into IE 5
Client Applications for XML
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Pass datasets to a browser. Browser script
can manipulate data (IE 4&5 only)
Client applications can retrieve XML data from
a web server for processing
Server Applications for XML
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Data can be stored in XML and combined with
XSL on the server to create HTML to be sent to
a browser
XML can be passed between applications
XML Resources
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http://msdn.microsoft.com/xml
http://xml.apache.org/
http://www.xml.com/
http://www.xmlmag.com/
http://www.ibm.com/xml
SOAP
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Simple Object Access Protocol
XML/HTTP based protocol for accessing
services in a platform-independent manner
Implementations exist in COM, ASP, Java, Perl
and maybe other languages
Reasons for SOAP
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Cross-Platform connectivity
Cross-Language connectivity
Object access through firewalls
SOAP Request
POST /StockQuote HTTP/1.1
Host: www.stockquoteserver.com
Content-Type: text/xml; charset="utf-8"
Content-Length: nnnn
SOAPAction: "Some-URI"
<SOAP-ENV:Envelope
xmlns:SOAP-ENV=http://schemas.xmlsoap.org/soap/envelope/
SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
<SOAP-ENV:Body>
<m:GetLastTradePrice xmlns:m="Some-URI">
<symbol>DIS</symbol>
</m:GetLastTradePrice>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
SOAP Response
HTTP/1.1 200 OK
Content-Type: text/xml; charset="utf-8“
Content-Length: nnnn
<SOAP-ENV:Envelope
xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
<SOAP-ENV:Body>
<m:GetLastTradePriceResponse xmlns:m="Some-URI">
<Price>34.5</Price>
</m:GetLastTradePriceResponse>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
SOAP Implementations
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MS Visual Studio 6 Wizard
Simon Fell’s COM server
Java from the Apache Group
Developmentor COM, VB, Perl implementation
CPAN Perl SOAP-Lite
SOAP Resources
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http://msdn.microsoft.com/xml
http://www.develop.com/soap
http://soap.weblogs.com/
http://www.zaks.demon.co.uk/com/index.html
Summary
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There are many tools available for web
development
Don’t overlook free tools!
Learn DHTML and XML and use them in your
projects
Questions
?