CSE 190: Internet ECommerce

1
CSE 190 Internet E-Commerce

• Lecture 9 Application Tier Programming

2
App Tier Languages

• Language paradigms, declarations, control flow,
  domain objects
• JSP -gt Java
• ASP -gt VB, C
• PHP -gt PHP, Java, COM

3
JSP

• Java paradigms
• All functionality encapsulated in objects
  functionality provided through methodspublic
  Classname instance-variables-block
  Type functionOne() . Type2 functionTwo()
  .
• Static typing
• Garbage collection
• Language reference Java in a Nutshell,
  http//java.sun.com
• Namespaces major components located in
  hierarchical namespaces (e.g. com.sun.net.)
• Methods accessible outside of the class must be
  prefixed with public token
• Essentially C-like syntax (including // and /
  / comments )
• Variables
• Type variableName initial-value
• E.g. String auctionTitle BMW motorcycle
• Array syntax variableName index
• Overloaded for string concatenation
• one two onetwo
• Visibility variables within methods visible
  until end of method
• Visibility variables within class are visible to
  all methods of class
• Lifetime intrinsic variables (e.g. int, float)
  have auto scope
• Within page declaration ltjspuseBean
  idvariableName classClassName
  scoperequest session application pagegt
• Property initialization ltjspsetProperty
  namevariableName propertypropertyName gt

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JSP Control flow

• Sequence
• statement1statement2
• All statements terminated by semicolon
• Selection
• if( boolean-value ) block
• block statement or block
• switch( integral-type ) case integral-value1
  statement-list breakdefault statement-list
  break

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JSP Control Flow

• Iteration
• for( int i 0 i lt 10 i ) block
• while( boolean-condition ) block
• do statement-list while( condition )
• No goto
• Method invocation
• object.actOnArguments( arg1, arg2, arg3 )
• Multithreading explicit
• Use synchronized( variable ) to avoid
  raceconditions may ignore this issue for DB
  calls

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JSP Types

• Intrinsics
• int, float, boolean, char, String
• String is an intrinsic object, with methods
  length(), etc.
• User defined types are always classes
• No enum, structs, typedefs

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JSP domain objects

• Request
• getParameter(), getCookies()
• Response
• addCookie(), encodeURL(), setStatus(),
  sendError()
• Out
• print, println
• Session
• getId(), getAttribute(), invalidate(),
  setAttribute(), removeAttribute()
• in
• pageContext
• config
• exception
• Overview http//jakarta.apache.org/tomcat/tomcat-
  4.0-doc/servletapi/overview-summary.html

8
JSP Review

• How would I create a class accessible to my JSP
  page that would provide access to a list of
  Auction objects, each with a small set of
  attributes?

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JSP Review

• import java.util.
• public class Auctions
• Vector _auctions
• public Auctions()
• reset()
• public int getNumAuctions()
• return _auctions.size()
• public Auction getAuction( int num )
• return (Auction) _auctions.elementAt( num
  )
• public void reset()
• _auctions.clear()

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JSP Review

• auction new Auction()
• auction.setTitle( "LOTR hobbit doll!!" )
• auction.setDescription( "Limited edition
  cloth doll showing all "
• "Frodo's
  features, including leaf clasp." )
• auction.setHighBidder( "(none)" )
• _auctions.add( auction )
• auction new Auction()
• auction.setTitle( "Automatic labeler" )
• auction.setDescription( "The Brother X7
  creates labels on demand "
• "through a simple
  keyboard. No waiting"
• " for the
  computer to boot up!" )
• auction.setHighBidder( "compulsive_collect
  or" )
• _auctions.add( auction )

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JSP Review

• public class Auction
• Properties _properties
• public Auction()
• _properties new Properties()
• public String getTitle()
• return _properties.getProperty( "title"
  )
• public void setTitle( String title )
• _properties.setProperty( "title", title
  )
• public String getDescription()
• return _properties.getProperty(
  "description" )

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JSP Review

• public String getHighBidder()
• return _properties.getProperty(
  "highbidder" )
• public void setHighBidder( String bidder )
• _properties.setProperty( "highbidder",
  bidder )

13
PHP

• PHP paradigms
• Perl-inspired syntax (mix of C, shell, and more)
• Functionality provided through functions or less
  commonly through methodsfunction printPage(
  arg1, arg2 ) statement-listclass
  MyClass function foo()
• Dynamically typed
• Garbage collection
• Language reference http//www.php.net
• Shell style comments this is a comment
• Variables
• auctionTitle BMW motorcycle
• Arrays arrayName index . Are associative
  arrays! Created with array().
• String concatenation (dot operator) one .
  two onetwo
• Visibility Auto scope

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PHP Control Flow

• Sequence
• statement1statement2
• Selection
• if( condition ) statement statement-list
  else .
• if( condition ) block elseif statement block
  
• switch()

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PHP Control Flow

• Iteration
• for(), while(), do while()
• foreach( arrayname as val )
• No goto
• Method invocation
• object-gtactionToPerform( arg1, arg2 )
• Persistent DB connections built in