Post on 28-Mar-2015
Other Web Application Development Technologies
PHP
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
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
PHP example
<HTML>…<BODY><H1>PHP Hello World Example</H1><?php echo ‘Hello world!’ ?>
</BODY></HTML>
PHP architecture
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
PHP/Web Server Architecture
web server (Apache, IIS, etc..)
Server Abstraction API (SAPI)
TS
RM
Zend Engine
PHP CorePHP extensions
TS
RM
PHP API
inputclient
HTMLpage
PHPpage
PHP Zend
parsingengine
webserver
datahttp request
outputHTML
http response
PHP and http
form processing example<html><head><title>Ice Cream Parlour </title></head><body>
<h1>Ice Cream Parlour</h1>
<form action = “ices.php” method = “POST”>
Flavour : <select name=“flavour”>
<option>vanilla</option>
<option>chocolate</option>
</select>
Scoops :<input type = “text” name = “scoops” />
</form>
</body></html>
form processing example<html>
<head><title>Ice Cream Response</title></head>
<body>
<h1>Thank you for your order</h1>
<?php
$flavour = $_POST [‘flavour’];
$scoops = $_POST [‘scoops’];
echo “$scoops scoops of $flavour coming right up!”;
?>
</body></html>
<HTML><head><title>self processing PHP page</title></head><BODY><?php if(!empty($_POST[‘name’])) { echo “Greetings, {$_POST[‘name’]}”;} else {?><FORM ACTION=“<?php $PHP_SELF; ?>”
METHOD=“POST”>Enter your Name:<INPUT TYPE=TEXT NAME=“name”><INPUT TYPE=SUBMIT>
</FORM><?php } ?> </BODY></HTML>
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 <html> tag)
cookies
• $_COOKIE array used for input
• setcookie () function sets cookie headers in the http response
<?php $accesses = $_COOKIE [‘accesses’]; setcookie (‘accesses’, ++$accesses);?>
• must be used before html content
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
simple hit counter<?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
?>
<html> … etc …
<p>This page has been viewed <?= $hits ?> times.
PHP and XML
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
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)
PHP and XSLT
<!-- sablotron version --><?php $processor = xslt_create ();
$result = xslt_process($processor,‘source.xml’,‘transform.xml’);
if(!$result) echo xslt_error ($processor); xslt_free ($processor); echo “<pre>$result</pre>”;?>
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
PHP strengths and weaknesses
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
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
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/
PHP web application frameworks
• Typical functionality
• CRUD (database interaction)
• M-V-C architecture
• Access control lists
• View helpers - AJAX, JavaScript, etc…
• Standard application components
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.
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.asp• contain HTML tags and scripting code• VBScript is the most widely used language
(although you can use JavaScript, other .NET languages)
The ASP Architecture
ASP.DLL
• 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.
A Simple ASP Example
<% @LANGUAGE = VBScript %><% Option Explicit %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<% ' File : clock.asp %><HTML><HEAD><TITLE>A Simple ASP Example</TITLE><META HTTP-EQUIV = "REFRESH" CONTENT = "60; URL=CLOCK.ASP">
</HEAD>
A Simple ASP Example
<BODY><H1>Simple ASP Example</H1><TABLE BORDER = "6"><TR>
<TD><% =Time() %></TD> </TR></TABLE></BODY></HTML>
ASP Built-in Objects
• Request
• Response
• Session
• Application
• Server
• ObjectContext
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.
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.
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.
Request Object Collections
• ClientCertificate
• Cookies
• Form
• QueryString
• ServerVariables
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.
Form Collection<FORM ACTION=“icecream.asp" METHOD=POST>
Name: <INPUT TYPE=TEXT NAME="name"><P>
Favourite Flavour: <SELECT MULTIPLE NAME=“flavour">
<OPTION>Mint<OPTION>Vanilla<OPTION>Coffee
</SELECT><P><INPUT TYPE=SUBMIT NAME=“iceSubmit" VALUE="Submit">
</FORM>
Form Collectionicecream.asp
Request.Form("name")Request.Form("flavour")
or<% For Each Item in Request.Form'code to display Item here
Next %>
ASP on Alternative Platforms
• Chili!ASP by Chili!Soft (Expensive to buy!)• Windows
– IIS, Apache, Netscape Enterprise & FastTrack, O’Reilly 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
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
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
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
ColdFusion
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
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
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
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)
ColdFusion Basics
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
client
HTMLpage
CFMLtemplate
ColdFusionApplication
Server
webserver
entity
entity
entity
datahttp request
input
outputHTML
http response
ColdFusion templates
• CFML tags embedded in HTML– Can produce pure CFML pages
• Tag Syntax– <CFTagname ... attributes ...> content
</CTTagName>– or <CFTagname ... attributes .../>
• trailing / optional
– Attributes are literals or expressions– Tags controlled by attributes and/or content
Example 1
<!--- simple output of variable values --->
<h2>Writing output</h2>
<CFSET xy = x * y />
<CFOUTPUT> x = #x#<br/> y = #y#<br/>x * y = #xy#<br/></CFOUTPUT>
Example 2<HTML><head><title></title></head><BODY><CFOUTPUT><H2>Today’s date is#DateFormat (Now (),’dd/mm/yy’)#</H2>
</CFOUTPUT></BODY></HTML>
CFML tag
closing CFML tag
Example 3
<CFMAILFROM = "jm@comp.rgu.ac.uk"TO = "honsISD@comp.rgu.ac.uk"SUBJECT = "Assessed Lab"SERVER = "mailhost@comp.rgu.ac.uk"
>Have a Merry Christmas.
</CFMAIL>
ColdFusion Web Application Framework
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
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
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
template request process
client
Server
myTemplate
applicationtemplate
onREquestEnd
request
response
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
ColdFusionstrengths and weaknesses
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
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