Other Web Application Development Technologies

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Other Web Application Development Technologies
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PHP
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PHP

• Personal Home Pages or PHP Hypertext
  Preprocessor
• language for creating HTML content
• normally runs as a server-side scripting language
• command line scripting possible
• client-side GUI applications using PHP-GTK
• generates other formats
• PDF, GIF, JPEG, PNG, Flash

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PHP

• free, open source technology
• extensive libraries of PHP code modules
• runs on all major operating systems
• runs with all major web servers (Apache, IIS,
  iPlanet)
• good database integration
• MySQL, Oracle, ODBC databases, PostgreSQL, Sybase

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PHP example

• ltHTMLgt
• ltBODYgt
• ltH1gtPHP Hello World Examplelt/H1gt
• lt?php echo Hello world! ?gt
• lt/BODYgt
• lt/HTMLgt

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PHP architecture
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PHP/Web Server Architecture

• web server layer
• handles http requests
• passes data to PHP via SAPI
• TSRM Thread-Safe Resource Management
• PHP language core
• PHP API (available to core and PHP extensions)
• Zend parsing engine
• runtime compiler
• executer

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PHP/Web Server Architecture
web server (Apache, IIS, etc..)
Server Abstraction API (SAPI)
PHP Core
PHP API
PHP extensions
TSRM
TSRM
Zend Engine
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PHP and http
http request
PHP page
data
client
PHP Zend parsing engine
web server
input
output
http response
HTML
HTML page
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form processing example
lthtmlgtltheadgtlttitlegtIce Cream Parlour
lt/titlegtlt/headgtltbodygt lth1gtIce Cream
Parlourlt/h1gt ltform action ices.php method
POSTgt Flavour ltselect nameflavourgt ltopti
ongtvanillalt/optiongt ltoptiongtchocolatelt/optiongt
lt/selectgt Scoops ltinput type text name
scoops /gt lt/formgt lt/bodygtlt/htmlgt
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form processing example
lthtmlgt ltheadgtlttitlegtIce Cream Responselt/titlegtlt/he
adgt ltbodygt lth1gtThank you for your
orderlt/h1gt lt?php flavour _POST flavour
scoops _POST scoops echo scoops
scoops of flavour coming right
up! ?gt lt/bodygtlt/htmlgt
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• ltHTMLgtltheadgt
• lttitlegtself processing PHP pagelt/titlegt
• lt/headgtltBODYgt
• lt?php if(!empty(_POSTname))
• echo Greetings, _POSTname
• else ?gt
• ltFORM ACTIONlt?php PHP_SELF ?gt
• METHODPOSTgt
• Enter your Name
• ltINPUT TYPETEXT NAMEnamegt
• ltINPUT TYPESUBMITgt
• lt/FORMgt
• lt?php ?gt lt/BODYgtlt/HTMLgt

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control of http response

• PHP sets standard headers by default
• response status line
• date, document length
• other headers added by web server
• header () function allows other headers to be set
• header (content-type text/plain)
• header must be used before any html generated
  (including leading lthtmlgt tag)

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cookies

• _COOKIE array used for input
• setcookie () function sets cookie headers in the
  http response
• lt?php
• accesses _COOKIE accesses
• setcookie (accesses, accesses)
• ?gt
• must be used before html content

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sessions

• PHP provides automatic session handling
• sessions set up using start_session() command
• PHP uses cookies to pass session information
• will switch to URL-rewriting if cookies disabled
• start_session() must appear at the start of the
  PHP document

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simple hit counter
lt?php session_start () /a unique session id
will be generated and stored in a cookie named
PHPSESSID / session_register (hits)
/sessions can load in variables registered in an
associative array called HTTP_SESSION_VARS/
hits //variable is incremented ?gt lthtmlgt
etc ltpgtThis page has been viewed lt? hits ?gt
times.
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PHP and XML
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PHP and XML

• PHP has strong text processing functionality
• comprehensive string manipulation
• strong regular expressions
• inherited or imported from Perl
• full set of filehandling functions for file I/O
• XML data files can be created/manipulated
  programmatically using text processing approaches

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PHP and XML

• DOM
• DOM processing from PHP 4.3
• DOM extension part of PHP 5 core
• XSLT
• libxslt extension in PHP 5
• A separate XSLT extension available from
  Sablotron C library (different API)

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PHP and XSLT

• lt!-- sablotron version --gt
• lt?php
• processor xslt_create ()
• result
• xslt_process(processor,source.xml,transform
  .xml)
• if(!result) echo xslt_error (processor)
• xslt_free (processor)
• echo ltpregtresultlt/pregt
• ?gt

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events-based XML programming

• PHP has an event-based XML parser
• based on libxml2 library
• SAX parser
• replaces old non-SAX Expat library
• parser calls handler functions as events occur
• you write the event handler functions

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PHP strengths and weaknesses
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PHP strengths

• free, open-source product
• flexible
• extensible
• easy to implement
• builds onto most browsers on most platforms
• familiar, flexible and powerful syntax
• with occasional weirdness thrown in
• good database connectivity
• technology of choice for low-end web-DB system

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PHP weaknesses

• XML support
• some non-standard features still in PHP5
• slow because of runtime compilation then
  execution
• derives from CGI script origins
• limited separation of coding from HTML
• no equivalent of JSP custom tags
• some open source versions emerging
• see http//trac.php-tools.net/
• extensibility limited by cumbersome C-based
  architecture
• this is improving with later versions

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PHP web application frameworks

• Frameworks are now emerging for PHP
• Cake
• Next lecture
• growing developer community, growing
  functionality
• http//www.cakephp.org/
• Symfony
• Very recent but stems from older projects
• established development community
• http//www.symfony-project.com/
• Zend Framework
• growing community of developers
• http//framework.zend.com/

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PHP web application frameworks

• Typical functionality
• CRUD (database interaction)
• M-V-C architecture
• Access control lists
• View helpers - AJAX, JavaScript, etc
• Standard application components

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Active Server Pages (ASP)

• Microsoft-based server-side processing technology
  
• ASP provides a server-side scripting environment.
• This includes
• Read information from an HTTP request.
• Customize an HTTP response.
• Interact with Databases.
• Support complex middleware.

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Active Server Pages (ASP)

• are processed in response to a client request
• ------ server-side scripting
• are processed by an ActiveX component
• ------ a scripting engine
• have the file extension .asp
• contain HTML tags and scripting code
• VBScript is the most widely used language
• (although you can use JavaScript, other .NET
  languages)

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The ASP Architecture
ASP.DLL
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• A user makes an http request for an ASP page.
• The .asp extension tells the Web server that the
  page contains server script (executable code)
  that it should process before returning the page
  to the browser.
• The server passes the ASP to the scripting engine
• The scripting engine executes ASP commands as it
  encounters them
• After execution of the server scripts, all code
  is stripped out of the page.
• The pure HTML page is sent in the http response.

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A Simple ASP Example

• lt _at_LANGUAGE VBScript gt
• lt Option Explicit gt
• lt!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0
  Transitional//EN"gt
• lt ' File clock.asp gt
• ltHTMLgt
• ltHEADgt
• ltTITLEgtA Simple ASP Examplelt/TITLEgt
• ltMETA HTTP-EQUIV "REFRESH" CONTENT "60
  URLCLOCK.ASP"gt
• lt/HEADgt

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A Simple ASP Example

• ltBODYgt
• ltH1gtSimple ASP Examplelt/H1gt
• ltTABLE BORDER "6"gt
• ltTRgt
• ltTDgtlt Time() gtlt/TDgt
• lt/TRgt
• lt/TABLEgt
• lt/BODYgt
• lt/HTMLgt

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ASP Built-in Objects

• Request
• Response
• Session
• Application
• Server
• ObjectContext

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ASP Built-in Objects

• Request
• Retrieves the values that the browser passes to
  the server during an HTTP request.
• Response
• Controls what information is sent to a browser in
  the HTTP response message.

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ASP Built-in Objects

• Session
• Used to manage and store information about a
  particular user session.
• Application
• Used to manage and store information about the
  Web application.

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ASP Built-in Objects

• Server
• Provides access to resources that reside on a
  server.
• ObjectContext
• Used to commit or abort a transaction managed by
  Microsoft Transaction Server (MTS) for ASP pages
  that run in a transaction.

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Request Object Collections

• ClientCertificate
• Cookies
• Form
• QueryString
• ServerVariables

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Form Collection

• The Form collection contains the values of each
  standard HTML control that has a NAME attribute.
  When a user submits a form with the POST method,
  you can read the values of the controls by using
  the Form collection.
• The Form collection of the Request object can be
  used to extract information from the body of an
  HTTP request message.

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Form Collection

• ltFORM ACTIONicecream.asp" METHODPOSTgt
• Name ltINPUT TYPETEXT NAME"name"gtltPgt
• Favourite Flavour
• ltSELECT MULTIPLE NAMEflavour"gt
• ltOPTIONgtMint
• ltOPTIONgtVanilla
• ltOPTIONgtCoffee
• lt/SELECTgtltPgt
• ltINPUT TYPESUBMIT NAMEiceSubmit"
  VALUE"Submit"gt
• lt/FORMgt

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Form Collectionicecream.asp

• Request.Form("name")
• Request.Form("flavour")
• or
• lt For Each Item in Request.Form
• 'code to display Item here
• Next gt

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ASP on Alternative Platforms

• Chili!ASP by Chili!Soft (Expensive to buy!)
• Windows
• IIS, Apache, Netscape Enterprise FastTrack,
  OReilly WebSite Pro
• Solaris
• Apache, Netscape Enterprise FastTrack
• Linux Apache
• IBM AIX Apache, Netscape Enterprise FastTrack,
  IBM HTTP Server, Lotus Domino Go
• HP UX
• Apache, Netscape Enterprise

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ASP on Alternative Platforms

• Instant ASP (iASP) by Halcyon Software
• cheaper
• written in Java as a Servelet, so runs with
  Apache/Tomcat and many other servers
• allows mix of ASP and JSP
• better range of functionality
• may run slow for high volume applications

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ASP Strengths

• implements M-V-C
• code embedded in the HTML
• separation of concerns
• no compiling - stays resident in memory
• no complex interfacing - method calls
• suitable for high-end web applications
• standard components
• re-use
• eases programming effort

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ASP weaknesses

• difficult to port between platforms
• steep learning curve for full functionality
• less suitable for low-end web apps
• multiplicity of .NET languages
• diffuse coding options
• can leave legacy problems

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ColdFusion
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ColdFusion

• Technology for building dynamic web applications
• provides powerful markup reducing need for
  programming skills
• designed for RAD abstracts many low-level tasks
  e.g. connection to a database

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ColdFusion

• runs on all major platforms
• compatible with all major browsers
• runs in CGI mode or as an embedded process
• runs on Apache, IIS, iPlanet
• ColdFusion applications are portable across
  platforms with very minor differences

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History of ColdFusion

• developed by Allaire software
• first version 1995 - only 30 language elements
• strongly tag-based, supplemented by functions
• Allaire merged with Macromedia in 2001
• MacroMedia ColdFusion
• ColdFusion MX
• ColdFusion MX 6.1 (2004)
• 80 tags, 255 functions

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use and availability

• Widely used for medium to large scale web apps
• Large developer community
• Not free, not open source
• ColdFusion MX Standard 929
• Windows, Linux
• ColdFusion MX Enterprise 4289
• Windows, Linux, Solaris, HP-UX, AIX
• 30-day free trial version (limited functionality)

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ColdFusion Basics
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ColdFusion Markup Language

• tag-based language (CFML)
• mixed with HTML, JavaScript/VBScript in a
  template
• CFML used to dynamically construct content
• CFML processed by ColdFusion Application Server
  on the server side

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CFML template
entity
input
http request
data
client
ColdFusion Application Server
web server
entity
entity
output
http response
HTML
HTML page
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ColdFusion templates

• CFML tags embedded in HTML
• Can produce pure CFML pages
• Tag Syntax
• ltCFTagname ... attributes ...gt content
  lt/CTTagNamegt
• or ltCFTagname ... attributes .../gt
• trailing / optional
• Attributes are literals or expressions
• Tags controlled by attributes and/or content

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Example 1
lt!--- simple output of variable values
---gt lth2gtWriting outputlt/h2gt ltCFSET xy x y
/gt ltCFOUTPUTgt x xltbr/gt y yltbr/gt x
y xyltbr/gt lt/CFOUTPUTgt
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Example 2

• ltHTMLgtltheadgtlttitlegtlt/titlegtlt/headgt
• ltBODYgt
• ltCFOUTPUTgt
• ltH2gtTodays date is
• DateFormat (Now (),dd/mm/yy)
• lt/H2gt
• lt/CFOUTPUTgt
• lt/BODYgt
• lt/HTMLgt

CFML tag
closing CFML tag
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Example 3
ltCFMAIL FROM "jm_at_comp.rgu.ac.uk" TO
"honsISD_at_comp.rgu.ac.uk" SUBJECT "Assessed
Lab" SERVER "mailhost_at_comp.rgu.ac.uk" gt Have
a Merry Christmas. lt/CFMAILgt
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ColdFusion Web Application Framework
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web application

• a group of templates forming a cohesive
  application
• maintain state
• utilise constants
• multi-threading
• error and exception handling
• security
• controlled through application template

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Application.cfm template

• reserved template name
• template placed in root directory of the web
  application
• executed before every request
• may be supplemented by OnRequestEnd.cfm template
• executed after every web request

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processing Application templates

• ColdFusion template requested
• ColdFusion searches template directory for an
  Application.cfm template
• ColdFusion processes Application.cfm template
  then requested template
• OnRequestEnd.cfm template processed if it exists

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template request process
Server
application template
client
request
myTemplate
response
onREquestEnd
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function of Application.cfm

• maintains state
• create Application, Client and Session variables
• set application constants
• data-source names, source directories, style
  elements
• handle errors
• provide security services
• user authentication
• entitlements

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ColdFusionstrengths and weaknesses
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strengths

• tag-oriented programming for web developers
• good support for custom tags and extensions
• full functionality to support medium to high end
  web systems
• supports MVC
• strong support for thread-safe transactions
• excellent database connectivity
• implemented on all major platforms

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weaknesses

• expensive compared with other technologies
• not open source
• highly redundant syntax
• leads to inconsistent development
• idiosyncratic language structure
• limited code re-use on or from other platforms
• non-standard and limited XML support